Download Major Components of My First App – Lab 1 Demos Jan. 19, 2017

Major Components of My First App – Lab 1 Demos
Jan. 19, 2017
Smartphone Screen Size Support,
http://developer.android.com/guide/practices/screens_support.html
• Screen size: small, normal, large, extra-large
• Screen density (unit: dot per inch, or dpi): six densities – low, medium, high, extra-high,
extra-extra-high, and extra-extra-extra high
• Orientation (landscape, portrait)
• Resolution (total number of physical pixels)
• Density-independent pixel (dp)
o A virtual pixel unit – used to express layout dimensions or position in a densityindependent way.
o 1 dp is equivalent to one physical pixel on a 160 dpi screen, which is the baseline
density assumed by system for a “medium” density screen.
o The conversion of dp units to screen pixels
 px = dp *( dpi/160)
o For example, on 240 dpi screen, 1 dp equals 1.5 physical pixel
• A set of six generalized densities:
o ldpi (low) ~ 120 dpi
o mdpi (medium) ~ 160 dpi
o hdpi (high) ~ 240 dpi
o xhdpi (extra-high) ~ 320 dpi
o xxhdpi (extra-extra-high) ~ 480 dpi
o xxxhdpi (extra-extra-extra-high) ~ 640 dpi
Major components of an Android app inside Android Project
• manifests
o AndroidManifest.xml
• java
o com.example.yourcompany.myfirstapp
 MyActivity.java
o com.example.yourcompany.myfirstapp
• res
o drawable
o layout
 activity_my.xml
o mipmap
 ic_launcher.png (5)
• ic_launcher.png (hdpi)
• ic_launcher.png (mdpi)
• ic_launcher.png (xhdpi)
•
•
•
o values
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Gradle Scripts
ic_launcher.png (xxhdpi)
ic_launcher.png (xxxhdpi)
colors.xml
dimens.xml
strings.xml
styles.xml
App Manifest, http://developer.android.com/guide/topics/manifest/manifest-intro.html
• Each app must have an AndroidManifest.xml file in its root directory.
• Manifest file presents essential info about your app to the Android system
• It serves the following purposes: It
o Names the Java package for the app
o Describes the components of the application
o Determine which processes will host application components – the activities,
services, broadcast receivers, and content providers that the app is composed of.
o Declares which permissions the app must have in order to access protected parts
of the API and interact with other applications
o Declares which permissions that others are required to have in order to interact
with the application’s components.
o Lists the Instrumentation classes that provide profiling and other information as
the application is running.
o Declares the minimum level of the Android API
o Lists the libraries that the application must be linked
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.lin.myfirstapp">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MyActivity">
<intent-filter>
<action
android:name="android.intent.action.MAIN" />
<category
android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
res.layout
activity_my_my.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_my"
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="com.example.lin.myfirstapp.MyActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!" />
</RelativeLayout>
res.values
colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
</resources>
dimens.xml
<resources>
<!-- Default screen margins, per the Android Design
guidelines. -->
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="fab_margin">16dp</dimen>
</resources>
strings.xml
<resources>
<string name="app_name">MyFirstApp</string>
</resources>
styles.xml
<resources>
<!-- Base application theme. -->
<style name="AppTheme"
parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item
name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>
</resources>
XML tags and nodes within AndroidManifest.xml,
http://developer.android.com/guide/topics/manifest/manifest-intro.html
<manifest>
<uses-permission />
<uses-sdk />
<uses-configuration />
<uses-feature />
o audio
o Bluetooth
o Camera
o Location
o Microphone
o NFC
o Sensors
o Telephony (GSM or CDMA)
o USB
o Wi-Fi
<application />
a manifest can contain only one application node; a container for
o activity
o service
o content provider
o broadcast receiver
</manifest>