Download Topic 17: More Bluetooth

ELET4133: Embedded Systems
Topic 17
More Bluetooth
Agenda
•
•
•
•
9/27/2013
What is Bluetooth?
General Terms
Turning Bluetooth off/on from your APP
Again, must be tested by an Android Device,
not the emulator
http://www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
2
Appreciation and Citation
• Special Thanks to Professor Glenys Gustin,
Associate Professor of CIS at Deleware County
Community College
– This presentation follows her three Youtube
Lectures about Bluetooth
– They can be viewed at:
• http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
• http://www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
• http://www.youtube.com/watch?v=X-Z4TiJTtlY&list=PLB4253C81CD49FF26
9/27/2013
http://www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
3
Past
• In the not-too-distant past computers used
RS232 cables for serial communication
between devices
• Now, we mostly
use USB when
wired connections
are necessary
• Now we connect
wirelessly
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
4
Wireless
• Today, most communications are wireless
– Bluetooth
– WiFi
• So,
• What is Bluetooth
Technology?
• What are the general
Terms?
• How do you turn it
off/on and use it?
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
5
Bluetooth Intro
• To test Apps, a Bluetooth device is required
– The emulator will not work
• Bluetooth uses the SPP (or RFCOMM)
– Bluetooth Serial Port Profile
– RF (Radio Frequency) COMM (communication)
– Simply known as the Bluetooth Transport
Protocol
• Provides serial data transfers via sockets
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
6
What is Bluetooth?
• A wireless communications protocol
• Constrained to short-range, line-of-site
communications
– Up to 50 meters
– Doesn’t work well through walls
– Used a lot for game technologies (Wii)
• Became popular with hands-free devices
• Enables peer-to-peer communications
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
7
What is Bluetooth?
• Bluetooth APIs have been available since
Android 2.0 SDK
• Android applications that have Bluetooth
hardware can:
– Scan for other Bluetooth devices
– Discover other Bluetooth devices
– Establish RFCOMM connections between the two
– Transfer data
– Maintain point-to-point and multipoint
connections
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
8
android.bluetooth API
• Bluetooth APIs are part of the
android.bluetooth package
• Android permits only encrypted connections
• Two devices must be bonded (paired) to
transfer data between them
• Once bonded you can connect later without
security prompts
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
9
Bluetooth API Classes
• BluetoothAdapter
– Hardware on the device
• BluetoothDevice
– Remote Bluetooth device
• BluetoothServerSocket
– Listens for incoming connections (Master device)
• BluetoothSocket
– Remote device uses this to connect to the Master
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
10
Bluetooth Permissions
• To use Bluetooth features in your application,
you must add these permissions to the
AndroidManifest.xml file for Bluetooth to
work
<manifest ... >
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
...
</manifest>
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
11
Communication Setup
• To start Bluetooth communications we have
four basic steps
– The 4 steps are usually handled in a separate
threads
• So that the calling (also called blocking) functions do
not make the App appear to hang
1.
2.
3.
4.
9/27/2013
Turn on Bluetooth for the device
Find paired or available devices within range
Connect devices
Transfer data between the devices
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
12
Introduction to Threads
9/27/2013
13
Java Threads
• A Thread is a public class that extends Object
and implements Runnable
• A Thread is a concurrent unit of execution
Representation of the main
program (Thread) running
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
14
Java Threads
• A Thread is a public class that extends Object
and implements Runnable
• A Thread is a concurrent unit of execution
Representation of the main
program (Thread) running
9/27/2013
Represents a new thread
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
15
Java Threads
• A Thread is a public class that extends Object
and implements Runnable
• A Thread is a concurrent unit of execution
Representation of the main
program (Thread) running
Represents a new thread
The main program is still running,
but the new thread begins
running simultaneously. If a
method in the new thread hangs,
stops, or just takes a long time,
the main program continues
running without problems
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
16
Java Threads
• A Thread is a public class that extends Object
and implements Runnable
• A Thread is a concurrent unit of execution
Representation of the main
program (Thread) running
Represents a new thread
The new thread eventually
finishes what it was designed to
do and stops
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
17
Java Threads
• A Thread is a public class that extends Object
and implements Runnable
• A Thread is a concurrent unit of execution
Representation of the main
program (Thread) running
Represents a new thread
You can have multiple threads,
but the more threads you have,
the more threads you have to
keep track of and ensure close
properly
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
18
Java Threads
• A Thread:
– It has its own call stack for methods being
invoked, their arguments and local variables
– Each application has at least one thread running
when it is started, the main thread, in the main
ThreadGroup
– The runtime keeps its own threads in the system
thread group
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
19
Java Threads
• There are two ways to execute code in a new
thread:
– You can either subclass Thread and overriding its
run() method
– Construct a new Thread and pass a Runnable to
the constructor
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
20
Program Preview
(What we plan to do)
9/27/2013
21
Bluetooth On/Off
• Before we get started, disable Bluetooth on your
phone because this APP will control its state
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
22
Program Preview
• The App we’re writing will show this screen:
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
23
Program Preview
• The App we’re writing will show this screen:
• When we press the connect
button, the system will
request persmission
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
24
Program Preview
• The App we’re writing will show this screen:
• When we press the connect
button, the system will
request persmission
• If we select [Yes] the system
will show us that it is turning
on the Bluetooth
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
25
Program Preview
• The App we’re writing will show this screen:
• When we press the connect
button, the system will
request persmission
• If we select [Yes] the system
will show us that it is turning
on the Bluetooth
• When on, we will see this
screen
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
26
Program Preview
• The App we’re writing will show this screen:
• When we select [Disconnect]
we will see the Bluetooth
icon disappear and a
message appear
• Then it will return to the first
screen
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
27
Starting the Project
9/27/2013
28
Background
• To Start: Begin a new project that has:
– Main.xml
• Has a text view
• 2 buttons
– One for Connect, one for Disconnect
• Image view for the Bluetooth icon
– Get an image and put it in the res/drawable folder
– Set permissions in AndroidManifest.xml
– Setup preliminary “stuff” in the java file
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
29
Java Setup
• Setup Java Class such that
– Set references for TextView, 2 Buttons, and
ImageView
– Develop the UI in the onCreate () method
• Get references for TextView, Buttons, and ImageView
• Setup the “setVisibility ()” method for each
• Setup onClick () methods for the Connect and
Disconnect Buttons (using AICs)
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
30
The Files: activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
All of the information for RelativeLayout
android:layout_height="wrap_content"
was set by default, by Eclipse, because a
android:text="@string/toptext" />
new Android project was created.
9/27/2013
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginTop="14dp"
android:text="@string/Button1" />
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
31
The Files: activity_main.xml
The TextView, two Buttons,
the ImageView, and the
image were drug from the
palette (or drawable
folder) to the Android
screen. Several attributes
were specified so that the
screen looked as shown, but
the rest was specified by
Eclipse, by default
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
32
The Files: activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
The items highlighted in
red are the ones changed.
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/toptext" />
9/27/2013
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginTop="14dp"
android:text="@string/Button1" />
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
33
The Files: activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
The items highlighted in
red are the ones changed.
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
The widths of the
android:text="@string/toptext" />
TextView, and the Buttons
were changed to
<Button
“match_parent” so that
android:id="@+id/button1"
they all were as wide as
android:layout_width="match_parent"
the screen itself
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginTop="14dp"
34
android:text="@string/Button1" />
9/27/2013
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
The Files: activity_main.xml
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="8dp"
android:text="@string/Button2" />
The widths of the
TextView, and the Buttons
were changed to
“match_parent” so that
they all were as wide as
the screen itself
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button2"
android:layout_alignRight="@+id/button2"
android:layout_below="@+id/button2"
android:layout_marginLeft="15dp"
android:layout_marginTop="28dp"
android:contentDescription="@string/descrip"
android:src="@drawable/bluetooth2" />
</RelativeLayout>
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
35
The Files: activity_main.xml
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="8dp"
android:text="@string/Button2" />
The widths of the
TextView, and the Buttons
were changed to
“match_parent” so that
they all were as wide as
the screen itself
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
The ImageView on the GUI
android:layout_alignLeft="@+id/button2"
was stretched manually,
android:layout_alignRight="@+id/button2"
so Eclipse chose to use
android:layout_below="@+id/button2"
alignLeft and alignRight
android:layout_marginLeft="15dp"
to set the width instead
android:layout_marginTop="28dp"
of the “match_parent”
android:contentDescription="@string/descrip"
android:src="@drawable/bluetooth2" />
</RelativeLayout>
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
36
The Files: activity_main.xml
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="8dp"
android:text="@string/Button2" />
The “descrip” attribute and
value “Bluetooth Icon” were
<ImageView
set to remove a warning – it
android:id="@+id/imageView2"
was not necessary
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button2"
android:layout_alignRight="@+id/button2"
android:layout_below="@+id/button2"
android:layout_marginLeft="15dp"
android:layout_marginTop="28dp"
android:contentDescription="@string/descrip"
android:src="@drawable/bluetooth2" />
</RelativeLayout>
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
37
The Files: activity_main.xml
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="8dp"
android:text="@string/Button2" />
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button2"
android:layout_alignRight="@+id/button2"
android:layout_below="@+id/button2"
android:layout_marginLeft="15dp"
The image bluetooth2.jpg
android:layout_marginTop="28dp"
was placed in the actual
android:contentDescription="@string/descrip"
res/drawable-hdpi folder
android:src="@drawable/bluetooth2" />
so that it was available
to the project
</RelativeLayout>
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
38
The Files: res/values/string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string
<string
<string
<string
<string
<string
name="app_name">BluetoothControl</string>
name="action_settings">Settings</string>
name="toptext">Bluetooth Not Connected</string>
name="descrip">Bluetooth Icon</string>
name="Button1">Connect Bluetooth</string>
name="Button2">Disconnect Bluetooth</string>
</resources>
Most of these were changed to match
the names in activity_main.xml
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
39
The Files: res/values/string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string
<string
<string
<string
<string
<string
name="app_name">BluetoothControl</string>
name="action_settings">Settings</string>
name="toptext">Bluetooth Not Connected</string>
name="descrip">Bluetooth Icon</string>
name="Button1">Connect Bluetooth</string>
name="Button2">Disconnect Bluetooth</string>
</resources>
Most of these were changed to match
the names in activity_main.xml
The “descrip” attribute and value
“Bluetooth Icon” were set to remove a
warning – it was not necessary
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
40
MainActivity.java
• Very little of the MainActivity.java file had
been created by Eclipse by default
• Lines create by Eclipse:
– The package name
– Basic imports statements
• When an error occurred, press [CNTRL][SHIFT]+O
– The class declaration
– The default parts of the onCreate ( ) method
– All highlighted in red on next page
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
41
src/packageName/MainActitivy.java
package com.example.bluetoothcontrol;
import
import
import
import
import
import
import
import
The lines in red were created by
android.app.Activity;
Eclipse by default.
android.os.Bundle;
android.view.Menu;
android.view.View;
android.view.View.OnClickListener;
android.widget.Button;
android.widget.ImageView;
android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created */
public TextView statusUpdate;
public Button connect;
public Button disconnect;
public ImageView logo;
9/27/2013
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupUI();
}
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
42
src/packageName/MainActitivy.java
package com.example.bluetoothcontrol;
import
import
import
import
import
import
import
import
android.app.Activity;
android.os.Bundle;
android.view.Menu;
android.view.View;
android.view.View.OnClickListener;
android.widget.Button;
android.widget.ImageView;
android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created */
public TextView statusUpdate;
The UI layout file defined a
public Button connect;
TextView, two buttons, and an
public Button disconnect;
ImageView. References to those
public ImageView logo;
objects are needed in the java
9/27/2013
file so they or their contents
@Override
can be manipulated. So these
protected void onCreate(Bundle savedInstanceState)
lines were entered {manually
super.onCreate(savedInstanceState);
and are the references to
setContentView(R.layout.activity_main);
those objects
setupUI();
}
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
43
src/packageName/MainActitivy.java
package com.example.bluetoothcontrol;
import
import
import
import
import
import
import
import
Errors were generated when the
reference lines were typed in
because these import statements
had not been entered.
android.app.Activity;
android.os.Bundle;
android.view.Menu;
android.view.View;
android.view.View.OnClickListener; By pressing [CNTRL][SHIFT]+O the
correct import statements were
android.widget.Button;
entered automatically by Eclipse
android.widget.ImageView;
and the errors were corrected.
android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created */
public TextView statusUpdate;
The UI layout file defined a
public Button connect;
TextView, two buttons, and an
public Button disconnect;
ImageView. References to those
public ImageView logo;
objects are needed in the java
9/27/2013
file so they or their contents
@Override
can be manipulated. So these
protected void onCreate(Bundle savedInstanceState)
lines were entered {manually
super.onCreate(savedInstanceState);
and are the references to
setContentView(R.layout.activity_main);
those objects
setupUI();
}
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
44
src/packageName/MainActitivy.java
package com.example.bluetoothcontrol;
import
import
import
import
import
import
import
import
android.app.Activity;
android.os.Bundle;
android.view.Menu;
android.view.View;
android.view.View.OnClickListener;
android.widget.Button;
android.widget.ImageView;
android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created */
public TextView statusUpdate;
public Button connect;
These lines were created
public Button disconnect;
automatically by Eclipse.
public ImageView logo;
9/27/2013
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupUI();
}
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
45
src/packageName/MainActitivy.java
package com.example.bluetoothcontrol;
import
import
import
import
import
import
import
import
android.app.Activity;
android.os.Bundle;
android.view.Menu;
android.view.View;
android.view.View.OnClickListener;
android.widget.Button;
android.widget.ImageView;
android.widget.TextView;
public class MainActivity extends Activity {
/** Called when the activity is first created */
public TextView statusUpdate;
public Button connect;
public Button disconnect;
The rest of the UI setup files
public ImageView logo;
could be written where this
line is, but the author chose
@Override
to jump to a new method,
protected void onCreate(Bundle savedInstanceState)
{
setupUI(), to finish and
super.onCreate(savedInstanceState);
“encapsulate” the remainder of
setContentView(R.layout.activity_main);
this task.
setupUI();
}
9/27/2013
http://www.youtube.com/watch?v=M5_EJ27xjMU&list=PLB4253C81CD49FF26
46
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
The setupUI() method finishes the task
connect.setVisibility(View.GONE);of completing the UI. The method ends
disconnect.setVisibility(View.GONE);
on the next page
logo.setVisibility(View.GONE);
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
47
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
These statements get the objects
/** set display view */
that were defined in the
connect.setVisibility(View.GONE);
activity_main.xml file and
disconnect.setVisibility(View.GONE);
referenced above and set with IDs
logo.setVisibility(View.GONE);
created by Eclipse and stored in
the R.java file. Here, we setup
connect.setOnClickListener(new OnClickListener() {
identifiers for each object so
@Override
that they may be used and
public void onClick(View v) {
manipulated by the program.
}
});
9/27/2013
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48
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
The two buttons and the
ImageView were just named
(previous slide). These
statements make sure that
they are not visible at
connect.setOnClickListener(new OnClickListener()
{
this time.
@Override
public void onClick(View v) {
}
});
9/27/2013
GONE is a constant whose value means to
make the View object invisible
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
49
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
This line sets the
/** set display view */
onClickListener for the connect
connect.setVisibility(View.GONE);
button. It will be handled by an
disconnect.setVisibility(View.GONE); Annymous Inner Class, but it has
logo.setVisibility(View.GONE);
not been developed yet
connect.setOnClickListener(new OnClickListener()
@Override
public void onClick(View v) {
}
});
9/27/2013
{
The AIC is everything between the enlarged
purple parantheses.
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
50
src/packageName/MainActitivy.java
disconnect.setOnClickListener(new OnClickListener () {
@Override
public void onClick(View v) {
This line sets the
}
onClickListener for the
disconnect button in the same
});
way that was just done for
the connect button. It will
} //End setupUI() method
be handled by an AIC, but,
like before, it has not been
@Override
developed
yet
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
9/27/2013
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51
src/packageName/MainActitivy.java
disconnect.setOnClickListener(new OnClickListener () {
@Override
public void onClick(View v) {
}
});
} //End setupUI() method
At this time, only the
default for the Options Menu
has been developed, and that
was done automatically by
Eclipse
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
9/27/2013
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52
Let’s Continue
(still working on the java file)
9/27/2013
53
MainActivity.java
package com.example.bluetoothcontrol;
import android.app.Activity;
First:create a reference
to a BlueTooth Adapter.
public class MainActivity extends Activity {
/** Called when the activity is first created */
private BluetoothAdapter btAdapter;
public
public
public
public
TextView statusUpdate;
Button connect;
Button disconnect;
ImageView logo;
“The BlueTooth Adapter class
initializes the BT hardware on
the device.”
We use the getDefaultAdapter()
method to retrieve information
@Override
about the BT interface
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupUI();
}
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54
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
When the user clicks the
/** set display view */
“Connect” button, we want to get
connect.setVisibility(View.GONE);
information about the BT hardware
disconnect.setVisibility(View.GONE); on the device. So, in the AIC we
logo.setVisibility(View.GONE);
use the getDefaultAdapter ()
method.
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
btAdapter = BluetoothAdapter.getDefaultAdapter();
}
});
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55
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
9/27/2013
Then we need some code to check
to see if there
is an adapter
{
connect.setOnClickListener(new OnClickListener()
present.
@Override
public void onClick(View v) {
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
statusUpdate.setText("Bluetooth is not on");
});
} www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
http://
56
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
If it is present and enabled, we
build a string
{ identifier and
connect.setOnClickListener(new OnClickListener()
send it to the text filed on the
@Override
screen
public void onClick(View v) {
9/27/2013
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
statusUpdate.setText("Bluetooth is not on");
});
} www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
http://
57
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
9/27/2013
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) { If it is not present and enabled,
btAdapter = BluetoothAdapter.getDefaultAdapter();
we send a string to the text
if (btAdapter.isEnabled()) field
{
on the screen to let the
String address = btAdapter.getAddress();
user know that
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
statusUpdate.setText("Bluetooth is not on");
});
} www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
http://
58
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
// connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
9/27/2013
connect.setOnClickListener(new OnClickListener()
If you want to{test it so far,
you must comment this line and
@Override
public void onClick(View v) { plug in a real device
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
statusUpdate.setText("Bluetooth is not on");
);
} http:// }
www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
59
src/packageName/MainActitivy.java
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
// connect.setVisibility(View.GONE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
9/27/2013
connect.setOnClickListener(new OnClickListener()
If you comment{the line and try
to emulate it, you will get an
@Override
public void onClick(View v) { error message because there is no
real device present
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
statusUpdate.setText("Bluetooth is not on");
);
} http:// }
www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
60
src/packageName/MainActitivy.java
• Before we go on:
– Move this section of code to the setupUI()
method
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
connect.setVisibility(View.VISIBLE);
statusUpdate.setText("Bluetooth is not on");
}
– This was done because we really want to
always check to see if the Bluetooth is enabled
9/27/2013
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61
src/packageName/MainActitivy.java
• Before we go on:
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
So this is how your
String address = btAdapter.getAddress();
setupUI() method
String name = btAdapter.getName();
should look now
String statusText = name+":"+address;
(with that section
statusUpdate.setText(statusText);
of code moved)
} else {
connect.setVisibility(View.VISIBLE);
statusUpdate.setText("Bluetooth is not on");
}
} // End of setupUI ()
– The author of this lecture rearranged a section
of code
9/27/2013
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62
Write the code necessary to connect
to the BT when we click on [CONNECT]
9/27/2013
63
Connect to Bluetooth Adapter
• Connectrate on just the Annonymous Inner
Class for the Connect Button
– What we have so far:
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
– Add some lines
9/27/2013
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64
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
This is a String for a Broadcast
Action that will broadcast that
the Bluetooth adapter has changed
state: i.e., On or Off. So, we
will have to implement (below) a
broadcast receiver
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
65
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
Creates a string for an activity:
A pop up a dialog box that will
ask the user if he wants to turn
the bluetooth adapter on or not
9/27/2013
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66
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
The Intent is what actually
displays the ACTION_STATE_CHANGED
string
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
67
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
We have to register a Broadcast
Receiver to accept the
ACTION_STATE_CHANGED sting. But,
until the broadcast receiver is
actually created, this line will
give an error
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
68
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
Then, we start a new Intent (and
wait for a result) so that the
program will know what the user’s
response was
9/27/2013
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69
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
So, now we need to test all this,
but the emulator will not show
anything because there is no
emulator Bluetooth device. So,
now an actual Android Device must
be plugged in so that the project
can be tested.
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
70
Connect to Bluetooth Adapter
• To test this, plug in the Android device and
click on DDMS in the Eclipse IDE
• Take a screen shot of the device
– Ensure that Bluetooth is Off
• The app is going to take care of turning it on
9/27/2013
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71
Connect to Bluetooth Adapter
• Bluetooth is off
9/27/2013
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72
Connect to Bluetooth Adapter
• Bluetooth is off
• In the IDE, choose
the Run
MainActivity.java
button to start the
emulation
9/27/2013
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73
Connect to Bluetooth Adapter
• TextView indicates
that the “Bluetooth is
not on”
• Press the [Connect
Bluetooth] button on
the device
9/27/2013
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74
Connect to Bluetooth Adapter
• Refresh the screen
and you should see
the dialog box
• Press [Yes]
9/27/2013
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75
Connect to Bluetooth Adapter
• You won’t see
anything on the main
screen
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
76
Connect to Bluetooth Adapter
• But go back to system
settings and you
should see that
Bluetooth is now on
9/27/2013
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77
Connect to Bluetooth Adapter
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
So, Bluetooth was turned on, but
we were not notified of the
change. That is the benefit of
implementing a Broadcast Receiver
9/27/2013
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78
Implement the Broadcast Receiver
9/27/2013
79
The Broadcast Receiver
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
First, uncomment the registerReceiver line
9/27/2013
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80
The Broadcast Receiver
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
IntentFilter filter = new IntentFilter(actionStateChanged);
registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (actionRequestEnable), 0);
}
});
First, uncomment the registerReceiver line
Then, enter the block of code for the Broadcast
Receiver. Place it before the onCreate() method
9/27/2013
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
81
The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
{
This is the first
toastText="Bluetooth turning on";
part of the
Toast.makeText(MainActivity.this, toastText,
Broadcast Receiver
Toast.LENGTH_SHORT).show();
(it wouldn’t all
break;
fit on one page)
}
case (BluetoothAdapter.STATE_ON):
{
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
9/27/2013
}
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
82
The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
Creates a new
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON): BroadcastReceiver and
its onReceive() method.
{
The onReceive() method
toastText="Bluetooth turning on";
executes whenever a new
Toast.makeText(MainActivity.this, toastText,
broadcast message is
Toast.LENGTH_SHORT).show();
sent out by the program
break;
}
case (BluetoothAdapter.STATE_ON):
{
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
9/27/2013
}
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
83
The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
Used as an int extra field in
{
ACTION_STATE_CHANGED
toastText="Bluetooth turning on";
intents to request the previous
Toast.makeText(MainActivity.this, toastText,
power state
Toast.LENGTH_SHORT).show();
break;
Possible values are: STATE_OFF,
}
STATE_TURNING_ON,
case (BluetoothAdapter.STATE_ON):
STATE_ON,
{
STATE_TURNING_OFF
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
9/27/2013
}
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
84
The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
Declaring state and prevState
{
(not used yet, so it is
toastText="Bluetooth turning on";
commented). The identifier
Toast.makeText(MainActivity.this, toastText,
state holds the current state of
Toast.LENGTH_SHORT).show();
the bluetooth device and
break;
getIntExtra retreives that state
}
case (BluetoothAdapter.STATE_ON):
{
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
9/27/2013
}
http:// www.youtube.com/watch?v=E6VlPklnQMY&list=PLB4253C81CD49FF26
85
The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
{
toastText="Bluetooth turning on";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
Then, we are going to have a toast
break;
(a pop up message window that
}
will display the different states of
case (BluetoothAdapter.STATE_ON):
the bluetooth device as it turns on
{
and off
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
9/27/2013
}
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The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
{
toastText="Bluetooth turning on";
Toast.makeText(MainActivity.this, toastText,
The switch-case block reads the
Toast.LENGTH_SHORT).show();
current state of the device and
break;
then displays different messages
}
based on its value
case (BluetoothAdapter.STATE_ON):
{
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
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}
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The Broadcast Receiver (part 1)
BroadcastReceiver bluetoothState = new BroadcastReceiver () {
@Override
public void onReceive (Context context, Intent intent) {
String prevStateExtra = BluetoothAdapter.EXTRA_PREVIOUS_STATE;
String stateExtra = BluetoothAdapter.EXTRA_STATE;
int state = intent.getIntExtra(stateExtra, -1);
//int prevState = intent.getIntExtra(prevStateExtra, -1);
String toastText="";
switch (state) {
case (BluetoothAdapter.STATE_TURNING_ON):
{
toastText="Bluetooth turning on";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
break;
The setupUI() is executed again for
}
either the Bluetooth ON or OFF
case (BluetoothAdapter.STATE_ON):
states, so that the main screen can
{
be redrawn properly
toastText="Bluetooth On";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
setupUI();
break;
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}
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The Broadcast Receiver (part 2)
case (BluetoothAdapter.STATE_TURNING_OFF):
{
toastText="Bluetooth turning on";
Toast.makeText(MainActivity.this, toastText,Toast.LENGTH_SHORT).show();
break;
The switch-case block reads the
}
current state of the device and
case (BluetoothAdapter.STATE_OFF):
then displays different messages
{
based on its value
toastText="Bluetooth Off";
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
setupUI();
break;
}
}
}
};
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The Broadcast Receiver (part 2)
case (BluetoothAdapter.STATE_TURNING_OFF):
{
toastText="Bluetooth turning on";
Toast.makeText(MainActivity.this, toastText,Toast.LENGTH_SHORT).show();
break;
}
case (BluetoothAdapter.STATE_OFF):
{
toastText="Bluetooth Off";
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
setupUI();
The setupUI() is executed again so
break;
that the main screen can be
}
redrawn properly
}
}
};
We still have one more thing to
take care of. In the setupUI()
method we had turned off the
disconnect button and the image.
We need to fix that
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The Broadcast Receiver
• Before we go on:
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
These are the lines
/** set display view */
that need to be
disconnect.setVisibility(View.GONE);
edited
logo.setVisibility(View.GONE);
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
} else {
connect.setVisibility(View.VISIBLE);
statusUpdate.setText("Bluetooth is not on");
}
} // End of setupUI ()
– The author of this lecture rearranged a section
of code
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The Broadcast Receiver
• Before we go on:
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
When the BT device
disconnect.setVisibility(View.VISIBLE);
is enable, we want
logo.setVisibility(View.VISIBLE);
to show the image
connect.setVisibility(View.GONE);
and the Disconnect
} else {
button
connect.setVisibility(View.VISIBLE);
statusUpdate.setText("Bluetooth is not on");
}
} // End of setupUI ()
– The author of this lecture rearranged a section
of code
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The Broadcast Receiver
• Before we go on:
private void setupUI() {
/** get objects, defined in activity_main.xml */
final TextView statusUpdate = (TextView)findViewById(R.id.textView1);
final Button connect = (Button) findViewById(R.id.button1);
final Button disconnect = (Button) findViewById(R.id.button2);
final ImageView logo = (ImageView) findViewById(R.id.imageView2);
/** set display view */
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter.isEnabled()) {
String address = btAdapter.getAddress();
String name = btAdapter.getName();
String statusText = name+":"+address;
statusUpdate.setText(statusText);
disconnect.setVisibility(View.VISIBLE);
And then, when the
logo.setVisibility(View.VISIBLE);
BT device is
connect.setVisibility(View.GONE);
disabled, we want
} else {
to turn off the
connect.setVisibility(View.VISIBLE);
image and show the
disconnect.setVisibility(View.GONE);
connect button
logo.setVisibility(View.GONE);
statusUpdate.setText("Bluetooth is not on");
}
} // End of setupUI ()
– The author of this lecture rearranged a section
of code
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Emulate Again
• First, turn off the
Bluetooth Adapter
and plug in the
Android Device
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Emulate Again
• Start the Emulator
and press the
connect button
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Emulate Again
• Press Yes for
permission to turn
the Bluetooth on
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Emulate Again
• And the Bluetooth is
turned on and this
screen comes up
• The toast message
was too fast to catch
• The disconnect
button doesn’t do
anything yet
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Disable Bluetooth
• We now have to setup the handler for the
disconnect button
• It is a lot simpler than everything we’ve done so far
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Disable Bluetooth
disconnect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
btAdapter.disable();
connect.setVisibility(View.VISIBLE);
disconnect.setVisibility(View.GONE);
logo.setVisibility(View.GONE);
statusUpdate.setText("Bluetooth Off");
}
});
All we have to do is disable the adapter, then
turn off the disconnect button and the image,
trun on the connect button, and print
“Bluetooth Off” the TextView area of the
screen
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Discovering Bluetooth Devices
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100
Discovering Bluetooth Devices
• Before the Bluetooth devices can establish a
Bluetooth Socket to communicate, they
must:
– Discover each other
– Create a bonded pair
• Our Android device must be set to be
discovered
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Discovering Bluetooth Devices
• Android devices have discoverability
disabled by default
• To trun on discoverability, the user must
provide permission
– Start a new Activity using
• ACTION_REQUEST_DISCOVERABLE
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Discovering Bluetooth Devices
• After Bluetooth is activated this device must
find available devices
– Use the BluetoothAdapter’s startdiscovery()
method
– Requires registering a BroadcastReceiver to
listen for ACTION_FOUND events
• Tells the App when a new Bluetooth device has been
discovered
• Our current Broadcast Receiver only implemented
an onReceive() method
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Scanning
• There are different ways of scanning for
discoverability
• To find which one is set, call getScanMode on
the Bluetooth Adapter
– Returns:
• SCAN_MODE_CONNECTABLE_DISCOVERABLE
– Discoverable for any device performing a discovery scan
• SCAN_MODE_CONNECTABLE
– Only devices that have previously been bonded can be found
• SCAN_MODE_NONE
– Discoverability is off
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Pairing with Bonded Devices
• Bonded devices are those that have been
paired with the current device in the past
• One connects as a server (our Android
device) and the other as a client
– Use the BluetoothSocket and
BluetoothServerSocket classes
– Use the getBondedDevices () method
Set <BluetoothDevice> pairedDevices = btAdapter.getBondedDevice;
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Pairing with Bonded Devices
• To establish a connection with another
device you must implement
• Client-side Socket or
• Server-side Socket
– After the server and client are bonded
• There is a connected Bluetooth socket for each
device on the same RFCOMM
– Radio Frequency Communication
– Or Bluetooth Transport Protocol
btAdapter.listenUsingRfcommWithServiceRecord(name, uuid);
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Pairing with Bonded Devices
• Bluetooth Service Discovery Protocol (SDP)
– Enables the device to register services to the
SDP database
– Enables the device to query the database for
available services
– Use SDP on a device to find the UUID of the
service with which you want to connect
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UUID
• Universally Unique Identifier
– Used for identification purposes
– 128 bit number presented in hex form
• Example: 8b28e550-7fef-11e1-b0c4-0800200c9a66
– You can get one for your Apps at:
• http://www.famkruithof.net/uuid/uuidgen
• Go to this URL and a unique UUID will be generated
for you
– It is then hardcoded into the App
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UUID
• Universally Unique Identifier
– Used for identification purposes
– 128 bit number presented in hex form
• Example: 8b28e550-7fef-11e1-b0c4-0800200c9a66
– You can get one for your Apps at:
• http://www.famkruithof.net/uuid/uuidgen
• Go to this URL and a unique UUID will be generated
for you
– It is then hardcoded into the App
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Back to the connect button handler
• Change the connect button’s
onClickListener () method
• The one we have already created, allowed
the App to turn on the Bluetooth device
• Now we want to enable the Bluetooth and
perform discovering simultaneously
• Go to the connect.onClickListener() method
and comment everything there
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Back to the connect button handler
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
//String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
//IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
//startActivityForResult(new Intent (actionRequestEnable), 0);
String scanModeChanged = BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
String beDiscoverable = BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
IntentFilter filter = new IntentFilter(scanModeChanged);
registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (beDiscoverable), DISCOVERY_REQUEST);
}
So, we basically setup a few new Strings as
});
we did before, a new Intent, and registered
the BroadcastReceiver. The we started the
new Activity, waiting for the result saying
when the devices were connected
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Back to the connect button handler
connect.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//String actionStateChanged = BluetoothAdapter.ACTION_STATE_CHANGED;
//String actionRequestEnable = BluetoothAdapter.ACTION_REQUEST_ENABLE;
//IntentFilter filter = new IntentFilter(actionStateChanged);
//registerReceiver(bluetoothState, filter);
//startActivityForResult(new Intent (actionRequestEnable), 0);
String scanModeChanged = BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
String beDiscoverable = BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
IntentFilter filter = new IntentFilter(scanModeChanged);
registerReceiver(bluetoothState, filter);
startActivityForResult(new Intent (beDiscoverable), DISCOVERY_REQUEST);
}
});
DISCOVERY_REQUEST should give an error until
you go to the top and define this constant
public class MainActivity extends Activity {
protected static final int DISCOVERY_REQUEST = 1;
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onActivityResult()
• We ended with a call to
startActivityForResult (new Intent……);
• Now, we need to develop a method to
handle the result.
• We call it onActivityResult()
– Shown on the next page
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onActivityResult()
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode = = DISCOVERY_REQUEST) {
Toast.makeText(MainActivity.this, "Discovery in progress",
Toast.LENGTH_SHORT);
setupUI();
findDevices();
}
}
Basically, this method will determine if
request code says that a discovery is in
progress, and if so, show that message in a
toast. Then it will call the setupUI()
method again to refresh the screen.
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findDevices()
@Override
private void findDevices(){
String lastUsedRemoteDevice = getLastUsedRemoteDevice();
if (lastUsedRemoteDevice != null) {
toastText = "Checking for known paired devices, namely:”
+lastUsedRemoteDevice;
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
// see if this device is in a list currently visible devices
Set <BluetoothDevice> pairedDevices = btAdapter.getBondedDevices();
for (BluetoothDevice pairedDevice : pairedDevices) {
toastText = "Found device: "+pairedDevice.getName() + "@" +
lastUsedRemoteDevice;
Toast.makeText(MainActivity.this,toastText,Toast.LENGTH_SHORT).show();
remoteDevice = pairedDevice;
}
}
}
This method should generate a few errors due
to methods that have not been declared yet
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findDevices()
@Override
private void findDevices(){
String lastUsedRemoteDevice = getLastUsedRemoteDevice();
if (lastUsedRemoteDevice != null) {
toastText = "Checking for known paired devices, namely:”
+lastUsedRemoteDevice;
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
// see if this device is in a list currently visible devices
Set <BluetoothDevice> pairedDevices = btAdapter.getBondedDevices();
for (BluetoothDevice pairedDevice : pairedDevices) {
toastText = "Found device: "+pairedDevice.getName() + "@" +
lastUsedRemoteDevice;
Toast.makeText(MainActivity.this,toastText,Toast.LENGTH_SHORT).show();
remoteDevice = pairedDevice;
}
To take care of most of these errors, type the
}
following with the other variable declarations
}
at the top of the file:
public String toastText = "";
private BluetoothDevice remoteDevice;
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findDevices()
• There are three more things to do
• We have to declare the
getLastUsedRemoteDevice() method
• Next page
• In the previous method, we defined instructions
in case the lastUsedRemoteDevice was NOT null
• We have to put in the instructions for what to do
if it is null
• We have to declare a new Broadcast Receiver
called discoveryResult
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getLastUsedRemoteDevices()
private String getLastUsedRemoteDevice() {
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
String result = prefs.getString("LAST_REMOTE_DEVICE_ADDRESS", null);
return result;
}
Looking for previous devices that have been used
with this before and returns their address
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2nd if in the findDevices() method
if (remoteDevice == null) {
toastText="Starting discovery for remote devices....";
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
// Start Discovery
if (btAdapter.startDiscovery()) {
toastText="Discovery Thread started... Scanning for Devices";
Toast.makeText(MainActivity.this, toastText,
Toast.LENGTH_SHORT).show();
registerReceiver(discoveryResult, new
IntentFilter(BluetoothDevice.ACTION_FOUND));
}
}
This is the second “if” in case the remoteDevice
is null: if the device had never connected to
another Bluetooth device before
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discoveryResult:
BroadcastReceiver discoveryResult = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent){
String remoteDeviceName =
intent.getStringExtra(BluetoothDevice.EXTRA_NAME);
BluetoothDevice remoteDevice;
remoteDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
toastText = "Discovered: " + remoteDeviceName;
Toast.makeText(MainActivity.this, toastText, Toast.LENGTH_SHORT).show();
//statusUpdate.setText(statusText);
}
};
Create a couple of strings. One is for the remoteDevice
name. then we create a toast that will display the
device name.
At this time I have commented the last line that will
update the main screens TextView
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findDevices()
• That takes care of most of it.
• This App (so far) will enable/disable
Bluetooth
• Discover and connect to remote device
• We still have to get a socket and transfer
data between devices
• Did that in the previous presentation
• At this point, it just takes experience
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Summary
• We discussed a lot!!
– We discussed exactly what Bluetooth is:
• Basically a wireless communications protocol
• General Terms:
• Bonded, paired, discover, scan, threads, etc
• Turning Bluetooth off/on from your APP:
• We looked very closely at methods to turn Bluetootj
on/off,
• Discover devices
• Connect devices, etc
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