In Intellij, how can I throw an exception at a break point?

Question

I see lots of questions about how to make Intellij break on exceptions. I'm trying to do something different: I want to throw an exception at a breakpoint so that I can see what will happen if an exception were to occur at that code.

I've figured out ways to force this. For example, if I have a variable called willBeUsed, I can hit a breakpoint and add a watch that says willBeUsed = null. This will trigger a NullPointerException eventually.

But I'm in a situation where I want to throw an IOException to see what happens. There's no way to trick my code into doing that. When I add a watch that says throw new IOException() it gives me an error saying, "unexpected tokens".

As a work around, I can modify the code to throw the exception and redeploy. But I'm wondering if there's a way to do this in the debugger without modifying source code.

Answer 1

You can right-click on stacktrace and choose 'Throw Exception'

(Since 2018.1 version. See JetBrains issue: IDEA-148408)

Answer 2

How about placing the throw statement in an if block, and only change the condition, e.g.:

boolean shouldThrowException = false; // .... if ( shouldThrowException ) //place breakpoint here {     throw new IOException(); } 

When you hit the breakpoint, change the value of shouldThrowException to true.