Exception Stacktrace Not Reporting Correct Line Number

elamda

Exception Stacktrace Not Reporting Correct Line Number

in Integration and Hardware • 2 months ago

I'm using Processing 2, and have multiple tabs. The exception is being thrown via an Interface, but the stacktrace isn't even showing the interface, only the original PDE filename.

I can of course println statements to try and figure out where all is going wrong, but that's a pretty tedious process. Is there a better way to get the accurate place the exception is occurring?

caused by: java.lang.ClassCastException: com.leapmotion.leap.FingerList cannot be cast to java.util.List
    at LeapTest$LeapDevice.getFingerVectors(LeapTest.java:134)
    at LeapTest$LeapDevice.getPos(LeapTest.java:119)
    at LeapTest.draw(LeapTest.java:41)

LeapTest is the original PDE file, LeapDevice is the interface where the exception is actually occurring.

Replies(2)

dimkir

Re: Exception Stacktrace Not Reporting Correct Line Number

2 months ago

To understand stack trace you need to understand that there's one more step Processing does before compiling.

When you have your sketch open with several .pde files, and then press run you may think that all the .pde files are compiled separately and then run. This is not true. What happens is that first "preprocessor" of Processing glues all of your .pde files (tabs) together into one big single .java file. It names it after your sketch. Hence in your stacktrace you see "LeapTest.java"

The stacktrace reports line numbers relative to LeapTest.java, not relative to your .pde file (tabs). So to figure out the line number you have to look at the generated (preprocessed) java file. You can find more info on how to get hold of thouse files there: https://forum.processing.org/topic/how-to-access-generated-java-files

elamda

Re: Exception Stacktrace Not Reporting Correct Line Number

2 months ago

Ah, thanks for that. Figured it was using one file.

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