How to Use the Debugger in IntelliJ IDEA: Setting Breakpoints and Step Controls

This article records the usage of the debugging tools in IntelliJ IDEA.

First, compile the program you want to debug.

1. Set Breakpoints

Click the left mouse button in the gutter next to the line number to set a breakpoint.

2. Start Debug Session

Click the green bug icon to begin debugging.

The Debug view appears at the bottom, showing the current execution line, call stack, and methods invoked up to the breakpoint.

3. Step Debugging

3.1 Step Over

Click the step over button to execute the current line and move to the next line.

3.2 Step Into

Click the step into button to enter a custom method on the current line.

Set a breakpoint in the custom method (e.g., f1()) and start debugging.

3.3 Force Step Into

This button forces entry into any method during debugging.

3.4 Step Out

Use step out to exit the current method and return to the caller after the method finishes.

3.5 Drop Frame

Drop frame returns execution to a previous method in the call stack, resetting variable values.

4. Advanced Debugging

4.1 Cross‑Breakpoint Debugging

Set multiple breakpoints and start debugging.

Click the button to move to the next breakpoint.

The program runs code between breakpoints; if no further breakpoint exists, clicking again runs to program end.

4.2 View Breakpoints

Click the button to see all set breakpoints and edit their properties.

Arrow 1 shows existing breakpoints; Arrow 2 sets conditional breakpoints (e.g., pause when c==97). Delete breakpoints after debugging.

4.3 Set Variable Values

During debugging, select a variable, right‑click, and choose Set Value to assign a new value, facilitating quick testing of conditions and loops.

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