Line breakpoints are set on an executable line of a program.
Directly to the left of the line where you want to add the breakpoint, open the marker bar pop-up menu and select Add Breakpoint. A new breakpoint marker appears on the marker bar, directly to the left of the line where you added the breakpoint. Also, the new breakpoint appears in the Breakpoints view list.
While the breakpoint is enabled, thread execution suspends before that line of code is executed. The debugger selects the thread that has suspended and displays the stack frames on that thread's stack. The line where the breakpoint was set is highlighted in the editor in the Debug perspective.
Debugger
Applying hit counts
Catching Java exceptions
Removing breakpoints
Enabling and disabling breakpoints
Managing conditional breakpoints
Setting method breakpoints
Stepping through
the execution of a program