Module 2: Debugging

The Scientific Method for Debugging

Finding bugs is perhaps the most challenging part of software development. To make it easier, developers use a systematic technique called the scientific method:

1. Reproduce the bug with a small, repeatable test
2. Study the available data including error messages and stack traces
3. Form a hypothesis about the location of the bug
4. Experiment to test the hypothesis
5. Repeat steps 2-4 until the bug is localized

Common Debugging Techniques

There are several techniques you can use to debug your code:

• Print statements: Add statements to show the values of variables at critical points
• Interactive debugger: Use your IDE's debugger to set breakpoints and inspect variables
• Code review: Examine the code to identify logical errors or potential issues
• Automated testing: Create tests that can reproduce the bug

Example: Debugging a Simple Program

public class MonthConverter {
    public static void main(String[] args) {
        if (args.length != 1) {
            System.out.println("Please provide a month number (1-12)");
            return;
        }
        
        int monthId = Integer.parseInt(args[0]);
        String monthName = findMonth(monthId);
        System.out.println("the month is " + monthName);
    }
    
    public static String findMonth(int monthId) {
        String monthName = "";
        switch (monthId) {
            case 1:
                monthName = "January";
                break;
            case 2:
                monthName = "February";
                break;
            case 3:
                monthName = "April"; // BUG: Should be March!
                break;
            case 4:
                monthName = "April";
                break;
            // remaining months...
        }
        return monthName;
    }
}