The Java development toolkit (JDT) includes a debugger that enables you to detect and diagnose errors in your programs running either locally or remotely.
The debugger allows you to control the execution of your program by setting breakpoints, suspending launched programs, stepping through your code, and examining the contents of variables.
The debugger has a client/server design so you can debug programs running remotely on other systems in the network as well as programs running locally on your workstation. The debug client runs inside the workbench on your workstation. The debugger server runs on the same system as the program you want to debug. This could be a program launched on your workstation (local debugging) or a program started on a computer that is accessible through a network (remote debugging).
Java development tools (JDT)
Changing debugger launch options
Connecting to a remote VM with the Remote Java application launch configuration
Disconnecting from a VM
Launching a Java program
Preparing to debug
Resuming the execution of suspended threads
Running and debugging
Run menu actions
Run and Debug toolbar actions