Edit/Debug Tool Bar

Open a file for editing. Starts a file chooser with which you can select a file to load into the the editor.
Save the current file
Start (or restart) the debugger
Set a breakpoint at the line in which the cursor is positioned
Evaluate a variable that you've selected in the editor
Resume execution of all threads. The threads run until one reaches a breakpoint, is suspended, or ends.
Run to here. Runs the program to the source line in which the cursor is positioned.
Step over a method. Executes one source line; if the source line is a method call, JDE executes the entire method without stepping through the individual method instructions.
Step into a method. Executes one source line; if the source line is a method call, the JDE executes the first statement of the method and stops.
Move one level up the call stack. The call stack includes all methods that have been called but have not returned to the caller. The methods in the call stack are listed in the order in which they were called. The method that was executing when the program stopped is at the top of the stack.
Move one level down the call stack. The call stack includes all methods that have been called but have not returned to the caller. The methods in the call stack are listed in the order in which they were called. The method that was executing when the program stopped is at the top of the stack.

See also:

Editing Source
Debugging Projects
What Is a Project?