IntelliJ IDEA 2018.3 Help

Starting the Debugger Session

Before debugging

Configure the debugger options. Specify the roots, dependencies and libraries to be passed to the Debugger.
  1. Set the breakpoints in the source code.

  2. If necessary, create or modify the corresponding Run/Debug configuration.

The debug session starts with the selected run/debug configuration. Note that several debug processes can be launched simultaneously.

When debugging an application in IntelliJ IDEA, keep in mind that

  • If the Make module before running/debugging/reloading option has been selected, IntelliJ IDEA first compiles all modified sources in your project.

  • IntelliJ IDEA proceeds with debugging, if compilation reports no errors.

  • If the code has not been compiled before debugging, the source and class files might be out of sync.

  • If you specify the -classpath option in the VM Options field, the selected module classpath will be overridden.

  • If you debug a JavaScript source, IntelliJ IDEA opens a browser for the HTML file with your script in a separate frame.

To start debugging an application

  • Select the run/debug configuration to execute, and then do one of the following:
    • Click icons toolwindows toolWindowRun svg icon in the left gutter, and then choose icons actions startDebugger svg.

    • Click icons actions startDebugger svg on the toolbar.

    • On the main menu, go to Run | Debug 'selected configuration'.

    • Press Shift+F9.

Note that after you've launched a debug session, the icons actions startDebugger svg icon that marks the Debug Tool Window toggles to debug active to indicate that the debugging process is active.

Last modified: 7 December 2018

See Also