Master IntelliJ IDEA Debugging: 5 Powerful Techniques to Boost Java Development

When developing Java projects, many developers are comfortable writing code in IntelliJ IDEA but lack deeper debugging skills beyond basic F7, F8, and F9 shortcuts.

This article introduces five practical debugging techniques to enhance productivity.

1. Conditional Breakpoint

Use a condition on a breakpoint to pause execution only when a specific value is reached, such as stopping a loop when i == 10.

Right‑click the red dot next to the breakpoint, select Condition , and enter the desired expression.

2. Drop Frame (Go Back One Step)

When execution has passed a point of interest, use the Drop Frame action to revert to the previous stack frame, allowing you to inspect variable values without re‑running the code.

3. Multithreaded Debugging

Set each breakpoint’s Suspend policy to Thread instead of All so that only the selected thread pauses, making it easier to follow complex concurrent flows.

Rename threads for clarity and choose the desired thread from the dropdown when a breakpoint hits.

4. Remote Debugging

4.1 Enable Remote Debugging on the Target JVM

java -server -Xms512m -Xmx512m -Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9081 ${main_class}

The essential flags are

-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9081

. Ensure the port is free and reachable from the local machine.

4.2 Configure IDEA for Remote Debugging

After setting up the remote configuration, place breakpoints in the source code and invoke a remote URL; the debugger will stop at the defined points.

5. Evaluate Expressions / Change Variable Values on the Fly

Click the + icon on the debugger toolbar to open an input box, type any expression (e.g., i+5), and press Enter to see the result instantly.

To modify a variable’s value, right‑click the variable and choose Set Value , then enter the new value.

By mastering these five techniques, developers can locate bugs faster, reduce debugging time, and enjoy a smoother development experience.