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1
Debugging
2
Debugging
• Despite the best efforts at design,
development, and testing, your code will
still likely contain errors.
• Programming is one of the most difficult
things people do!
• When you have errors, how do you find
them?
– Use System.out.println (slow, painful way)
– Use a debugger (much better way)
3
How to Debug
• Right-click on the java file with the main
function
• Select Debug as…→Java Application
• You may be asked to switch to the
Debug Perspective. Just click on yes.
4
Breakpoints
• If you follow the steps from the previous
slide, you probably will just run through
the entire program and not stop
• You need to put a breakpoint in your
code
• Breakpoint: A place in your code where
you would like to pause while
debugging
Breakpoints
To place a breakpoint,
right click in the margin
on the line you want to
pause at. Select “toggle
breakpoint”. You should
see a blue circle.
To remove a breakpoint,
click on the blue circle
and select “Toggle
breakpoint” again.
6
Debugging
Key commands:
1. Step over: don’t go into the function call on
the line you are on
2. Step into: go into the function call on the
line you are on
3. Step return: go to the next line of the
calling function
4. Run to line: run to the line that the cursor is
on
5. Resume: run until you hit the next
breakpoint or your program ends
6. Terminate
