Applications

Applications
in Java

Prof. David Bernstein
James Madison University

Computer Science Department

bernstdh@jmu.edu

What Are They?

Program (in an Object-Oriented Language):
- A group of cooperating classes with a well-defined entry point (i.e., a method that should be executed first)and, perhaps, a re-entry point and/or an exit point.
Application:
- Runs under the operating system
- Entry point is main()
- Top-level container is usually a JFrame (or Frame)

Applications in Java

The Application Lifecycle in Java

When an application is started the main() method is executed in a non-daemon thread called the main thread.
A single-threaded application terminates when the System.exit() method is called, in response to a platform-specific event such as a SIGINT or a Ctrl-C, or when the main thread "drops out of" the main() method.
A multi-threaded application terminates when the System.exit() method is called, in response to a platform specific event, or when all non-daemon threads have died.

Starting Applications

The JVM can be started and informed of what application to start by typing:
java application
at the command line
Applications in (executable) JAR files can be started by clicking/double-clicking on the JAR file.
The CLASSPATH environment variable is used to identify the location of packages.
To pass parameters to an application at the command line, include them after the application.