Exception Handling & Debugging

💻 Exception Handling & Debugging – Mini Study Guide

🔎 PART 1: Debugging Concepts and Techniques

🧠 What is Debugging?

Debugging = the process of finding and fixing errors (bugs) in a program that causes unexpected behavior.

This part is important kasi ito ‘yung foundation ng topic. If you can’t debug, you can’t survive programming 😭.

According to the handout

• It identifies errors

• It fixes unexpected behavior

• It’s one of the most time-consuming parts of coding

Think of debugging like being a detective. 🕵‍♂️
Something’s wrong → you investigate → you find the culprit → you fix it.

🔁 The Typical Debugging Process

1⃣ Examine the Error Symptoms

• Look at crashes

• Read error messages

• Observe weird behavior

Example:
If your calculator app suddenly closes when dividing by 0, that’s a symptom.

2⃣ Identify the Cause

• Trace the code execution

• Find the exact line causing the issue

Example:
You realize the denominator was 0 → boom 💥 division by zero.

3⃣ Fix the Error

• Modify the code

• Test again

• Make sure it works properly

In short:

🛠 Debugging Techniques (Super Important 🔥)

1⃣ Understanding the Problem

Before changing code, understand it muna.

If you don’t understand the problem:

• You waste time

• You create new bugs

💡 Reproduce the issue first.

2⃣ Backtracking (Backward Debugging)

Start from where the error happened → trace backward.

Good for:

• Complex systems

• Hard-to-trace bugs

Parang reverse engineering.

3⃣ Debugging Tools

Tools help you:

• Inspect variables

• Check memory usage

• Monitor execution

Examples from the handout:

• Chrome DevTools

• Testsigma

• dbForger

4⃣ Breakpoints & Stepping

Breakpoint

Stops program execution temporarily.

Why?
To inspect:

• Variable values

• Program state

Stepping

Move through code line by line manually.

This is like slow-mo mode for your program 🐢.

5⃣ Binary Search Debugging

Divide code into halves.
Test each half.
Narrow down the issue.

Best for:

• Large codebases

• Hard-to-find bugs

6⃣ Rubber Ducking 🦆

Explain your code out loud.

Yes, literally.

When you explain your logic clearly, you often realize:
“Omg, mali pala dito.”

7⃣ Log Analysis

Insert log statements (e.g., print statements).

Check:

• Variable values

• Execution flow

8⃣ Clustering Bugs

Group similar bugs together.

Fixing one might fix others.

Efficiency level = 📈

9⃣ Take Breaks

Your brain isn’t a robot.

Sometimes stepping away = clarity.

🔟 Take Notes

Document:

• What failed

• What worked

• What you changed

Future you will thank you.

🔥 Debugging Summary Mnemonic:

U B D B B R L C B N

Understanding
Backtracking
Debug tools
Breakpoints
Binary search
Rubber duck
Log analysis
Clustering
Break
Notes

⚠ PART 2: Basic Exception Handling

🤔 What is an Exception?

An exception is an unexpected event during program execution.

Examples:

• File doesn’t exist

• Disk full

• Invalid user input

• Divide by zero

• Invalid array index

Important:
Not all exceptions are “bad” — they’re just unusual conditions.

🕒 Runtime Error vs Syntax Error

🚨 Error Class vs Exception Class (Java)

Java has 2 main categories:

Think of it like:

• Error = System level problem 💀

• Exception = Program-level issue you can handle 💪

🌳 Exception Hierarchy (Important for Exams)

From page 3:

Object
→ Throwable
 → Exception
 → Error

So:

Common Exceptions You MUST Know

🔢 ArithmeticException

Division by zero.

📏 IndexOutOfBoundsException

Invalid index in array/list/string.

📥 InputMismatchException

Wrong data type input.

Example:
User enters "three" instead of 3.

💾 IOException

File handling issues.

💻 Division Program Example (From Handout)

Original code divides numerator by denominator.

Problem scenarios:

When denominator = 0 → crash 💥
When input is not integer → crash 💥

That crash message list is called:
👉 Stack Trace

🧩 try, catch, finally Blocks

Now this is the heart of exception handling.

🔹 try Block

Used when:
You know something risky might happen.

Structure:

try {
   risky code
}

🔹 catch Block

Handles the exception.

Structure:

catch(ExceptionType e) {
   handle error
}

Important:

• It’s not a method.

• It catches thrown exceptions.

🔹 finally Block

This runs:

• Whether error happens or not

• Always executes

Used for:

• Closing files

• Releasing resources

• Cleanup

Example from handout:

Even if file reading fails, the file still closes in finally.

🔁 try-catch Flow (Simple Explanation)

1. Try runs

2. If no error → skip catch

3. If error → jump to catch

4. Finally always runs

🧠 Visual Logic Flow

try {
   risky code
}
catch(Exception e) {
   handle error
}
finally {
   cleanup
}

Think of it like:

Try = attempt

Catch = damage control

Finally = clean your mess

🎯 Quick Comparison: Without vs With try-catch

🧠 FINAL RECAP (Memory Tricks)

🔥 Debugging = 3 Steps

SEE – FIND – FIX

🔥 Exceptions

Unexpected events during execution.

🔥 Java Error Types

Error = unrecoverable

Exception = recoverable

Mnemonic:

🔥 try-catch-finally

Try = Risk

Catch = Handle

Finally = Cleanup

Mnemonic:

🔥 Most Common Exceptions to Remember

AIIIO

Arithmetic

IndexOutOfBounds

InputMismatch

IOException

OutOfMemoryError