Download CS 201 Lecture 1 (b) Using an IDE

CS 201 Lecture 1 (b)
Using an IDE
Tarik Booker
CS 201: Introduction to Programming
California State University, Los Angeles
What we will cover…
• Basic Java Programming (Review)
• Creating, Compiling, Executing a Java Program
• Using an IDE
• Textpad
• Eclipse
• JDK
Creating Compiling, and
Executing a Java Program
• You have to create your own program
• Make sure it works
• If it doesn’t compile you will not be able to run it!
• You can compile and run from a command window!
Compiling and Running a File
• Write your program
• Save as .java
• Type
• javac filename.java
• Javac = java compile
• Compiles to a .class file(s)
• Run
• java classname.class
• Runs this within a JVM (Java Virtual Machine)
The Java Virtual Machine
• The Java Virtual Machine (JVM) is the runtime environment
• A virtual computer that runs your environment
• Runs “around” the CPU
• Creates a layer between the CPU and the Java Program
• Java is compiled down to bytecode
• Not machine language
• JVM is run between the CPU and the Program
• Slower than something run directly on the CPU
• This makes the program portable
• Different JVM’s for different computers (CPUs)
Programming Style
• Make sure you do the following:
• Appropriate Comments
• Proper Indentation and Spacing
• Space operators
• Block Styles
• Next-line style
• End of line style
Errors
• There are three possible errors in java
• Syntax Errors
• Problems with spelling
• Missing characters
• Runtime Errors
• Abnormal termination
• Logic Errors
Using an IDE
• Use Textpad or Netbeans
• Eclipse is a very powerful IDE we will cover later
• Good luck!
Textpad
• Go to Textpad
• https://www.textpad.com/download/index.html
• Download The IDE
• Officially Shareware
• (Free to download, should pay)
Textpad (2)
• Install and then run
• Textpad will install on your
computer.
Compiling and Running Using
the Command Line
• Use a text editor (Whatever you choose)
• Save the file as .java
• Open a command window:
• Click the start button
• Type in cmd
• (or look for command window in programs)
Compiling and Running Using
the Command Line (2)
• Use DOS commands to locate your java file
• http://www.colorado.edu/geography/gcraft/tips/doshelp.html
• Get to the location of your file
• Type javac filename.java
• Should be the same name as your class
Compiling and Running Using
the Command Line (3)
• Look at our example:
• Class name is Hello
• Filename should be Hello.java
• When we compile, should result in the class name
• Hello.class
• To run the program, we must run the class through
the JVM (called “java”)
• java Hello
• Note: don’t type in
• java Hello.class (WRONG)
Compiling and Running Using
the Command Line (4)
• Results:
Compiling and Running Using
the Command Line (5)
• Note: If you just want to use the command javac automatically
(without using the path name), you must add the path to the
computer path
• Type in “path” at the command line
• Gives all folders to look for commands
Compiling and Running Using
the Command Line (6)
• After you install the JDK, add the bin folder to the path
• To change the system path (Windows), perform these steps:
• Start the System Control Panel applet (Start - Settings - Control Panel
- System).
• Select the Advanced tab.
• Click the Environment Variables button.
• Under System Variables, select Path, then click Edit.
• Other ways (try Windows version first):
• After this, you can call javac and java (jvm) directly
Using Eclipse
• Eclipse is a very powerful IDE that can be used to develop Java
programs
• Very complicated to use at first
• Complex now, later very convenient
• Download
• http://www.eclipse.org/
• Install
• Very large file
Eclipse (2)
• Creating a new project
• Instead of creating a new file, you must first create a project
• Holds all files associated with the program
• Not as necessary now, effective later
• File -> New -> Java Project
• Type demo in the Project Name field
• Select “Use project folder as root for sources and class files”
• Puts java and class files in same folder
• Click Finish
Eclipse (3)
• Creating a new Class
• File -> New -> Class
• Opens New Java Class Wizard
• Type Welcome
• Our class name
• Check option public static void main(String[] args)
• Click Finish
Eclipse (4)
• Compiling and Running a Class
• Right-click the Class in Project Display
• Select Run -> Java Application
• In context menu
• Output is displayed in Console pane