Launching a Java program
The simplest way to launch a Java program is to run it using a Java Application launch configuration. This launch configuration type uses information derived from the workbench preferences and your program's Java project to launch the program.
In the Package Explorer, select the Java compilation unit or class file you want to launch.
From the pop-up menu, select Run > Java Application.
Alternatively, select Run > Run As > Java Application in the workbench menu bar, or select Run As > Java Application in the drop-down menu on the Run tool bar button.
Your program is now launched, and text output is shown in the Console View.
You can also launch a Java program by selecting a project instead of the compilation unit or class file. You will be prompted to select a class from those classes that define a main method. (If only one class with a main method is found in the project, that class is launched as if you selected it.)
Creating a Java application launch configuration
When you choose Run > Run As > Java Application to launch your class, you are running your class using a generic Java Application launch configuration that derives most of the launch parameters from your Java project and your workbench preferences. In some cases, you will want to override the derived parameters or specify additional arguments.
You do this by creating your own Java Application launch configuration.
Select Run > Run... or Run > Debug... from the workbench menu bar. This opens a dialog that lets you create, modify, and delete launch configurations of different types.
Select Java Application in the left hand list of launch configuration types, and press New. This will create a new launch configuration for a Java application. The tabs on the right hand side allow you control specific aspects of the launch.
The Main tab defines the class to be launched. Enter the name of the project containing the class to launch in the project field, and the fully qualified name of the main class in the the Main class field. Check the Stop in main checkbox if you want the program to stop in the main method whenever the program is launched in debug mode.
Note: You do not have to specify a project, but doing so allows a default classpath, source lookup path, and JRE to be chosen.
The Arguments tab defines the arguments to be passed to the application and to the virtual machine (if any). You can also specify the working directory to be used by the launched application.
The JRE tab defines the JRE used to run or debug the application. You can select a JRE from the already defined JREs, or define a new JRE.
Note: Changing the JRE used for running does not affect the way Java source is compiled. You can adjust the build path to compile against custom libraries.
The Classpath tab defines the location of class files used when running or debugging an application. By default, the user and bootstrap class locations are derived from the associated project's build path. You may override these settings here.
The Source tab defines the location of source files used to display source when debugging a Java application. By default, these settings are derived from the associated project's build path. You may override these settings here.
The Environment tab defines the environment variable values to use when running or debugging a Java application. By default, the environment is inherited from the Eclipse runtime. You may override or append to the inherited environment.
The Common tab defines general information about the launch configuration. You may choose to store the launch configuration in a specific file and specify which perspectives become active when the launch configuration is launched.