1. Wrapper Classes Debugging Interlude 1
2/12/15
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

2. Objectives Define the terms bug and debugging.
Explain what a compile-time error is.
Explain what an execution-time error is.
Give examples of compile-time errors.
Give example of execution-time errors.
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

3. Bugs and Debugging Bug Debugging Debugger Any error in a program.
Grace Hopper's team logged a "bug" in 1945
Debugging
Fixing errors.
Debugger
Special software to help fix programs.
Usually part of IDEs like eclipse.
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

4. Syntax Errors Error that keeps the program from compiling.
Missing or Extra Semicolons
Spelling and Capitalization
Missing quote, parenthesis, or braces
Missing operators
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

5. More Syntax Errors Missing concatenation in println
Unintialized Variables
Not assigned value
DebugSyntax
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

6. Execution-Time Errors
Logical Errors in a program
Examples
Incorrect Arithmetic.
Divide by zero.
Bad input.
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010

7. Debugging Techniques
Visually inspect the code (not every test requires modifying/running the code).
Manually set a variable to a value.
Insert print statements to observe variable values.
Comment out unused code.
Example in DebugExecution.java

8. Using eclipse Debugger
Can set breakpoints.
Can inspect variable contents.

9. Questions
What is the difference between a syntax error and a execution error?
Does Java always give helpful error messages?
What can you do to help debug logic errors?