java

title	How to Debug Java with VSCode
permalink	/java/

How to Debug Java with VSCode

Summary

• Basic, Spec
• Unit Test: junit
• executable file debug
• attach running and remote process

Basic

• Java
• Extension:Java Debug Extension for Visual Studio Code
• Debugger: jdb
• module code: src/main/java/com/j74th/vscodedebugbook/bubblesort/BubbleSort.java

Spec

• OS
  • ✅ MacOS
  • ✅ Windows
  • ？ Linux
• Break Point
  • ✅ break point
  • ✅ condition break point
  • ❌ function breakpoint
• Step Execution
  • ✅ Step Over
  • ✅ Step Into
  • ✅ Step Out
  • ✅ Continue
  • ❌ Step Back
  • ❌ Move To
  • ❌ Pause
• Variables
  • ✅ variables views
  • ✅ watch variables
• Call Stack
  • ✅ call stack
• Evaluation
  • ✅ eval expression to show variables
  • ❌ eval expression to change variables
• Type of Execution
  • ✅ debug unit test
  • ✅ debug executable package
  • ✅ remote debugging

unit test (Junit)

launch.json

• test code: src/test/java/com/j74th/vscodedebugbook/bubblesort/BubbleSortTest.java

{
	"version": "0.2.0",
	"configurations": [
		{
            "type": "java",
            "name": "Test Debug (Launch)",
            "request": "launch",
            "mainClass": "junit.textui.TestRunner",
            "args": "com.j74th.vscodedebugbook.bubblesort.BubbleSortTest"
		}
	]
}

executable file debug

• Program: src/main/java/com/j74th/vscodedebugbook/bubblesort/BubbleSorter.java

launch.json

{
	"version": "0.2.0",
	"configurations": [
		{
            "type": "java",
            "name": "Debug (Launch)",
            "request": "launch",
            "mainClass": "com.j74th.vscodedebugbook.bubblesort.BubbleSorter",
            "args": "4 3 2 1"
		}
	]
}

attach running and remote process

launch.json

{
	"version": "0.2.0",
	"configurations": [
		{
            "type": "java",
            "name": "Debug (Attach)",
            "request": "attach",
            "hostName": "localhost",
            "port": 5005
		}
	]
}

how-to

1. run program with debug option
   • set suspend=y when you like to stop before attach, othrewise suspend=n when you like to start right away.

java -cp target/classes -Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=5005,suspend=y com.j74th.vscodedebugbook.bubblesort.BubbleSorter 4 3 2 1

2. start debug