Debugging

How

• Fix don't blame
• Reproduce
• Failing test
• Read the error message
• Binary Chop
• Logging / Tracing

Stack Traces

Caused by: java.lang.NullPointerException <-- root cause
        at com.example.myproject.Book.getId(Book.java:22) <-- important line

Terms:

• topmost line on top of the stack
• root cause
• important line usually app code (other than library/framework) ("Select isn't broken" from Pragmatic Programmer)