[debugging] Attach IntelliJ IDEA debugger to a running Java process

Is it possible to attach the IntelliJ IDEA debugger to a running Java process? If yes, how?

It's possible, but you have to add some JVM flags when you start your application.

You have to add remote debug configuration: Edit configuration -> Remote.

Then you'lll find in displayed dialog window parametrs that you have to add to program execution, like:

-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005

Then when your application is launched you can attach your debugger. If you want your application to wait until debugger is connected just change suspend flag to y (suspend=y)

Also I use Tomcat GUI app (in my case: C:\tomcat\bin\Tomcat9w.bin).

• Go to Java tab:

  

• Set your Java properties, for example:

  Java virtual machine

  C:\Program Files\Java\jre-10.0.2\bin\server\jvm.dll

  Java virtual machine

  C:\tomcat\bin\bootstrap.jar;C:\tomcat\bin\tomcat-juli.jar

  Java Options:

  -Dcatalina.home=C:\tomcat

  -Dcatalina.base=C:\tomcat

  -Djava.io.tmpdir=C:\tomcat\temp

  -Djava.util.logging.config.file=C:\tomcat\conf\logging.properties

  -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:8000

  Java 9 options:

  --add-opens=java.base/java.lang=ALL-UNNAMED

  --add-opens=java.base/java.io=ALL-UNNAMED

  --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED

in AndroidStudio or idea

1. Config the application will be debug, open Edit Configurations

add "VM Options" Config “-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005” remember "address"

2. Config Remote Debugger if not exits, Click + to add

specify "Port" same as in Step 1 "address"

Also, don't forget you need to add "-Xdebug" flag in app JAVA_OPTS if you want connect in debug mode.