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Course/Module 7/Topic 1 of 3Intermediate

Try-Catch-Finally Blocks

Exception handling lets you gracefully handle errors without crashing. The try-catch-finally structure catches exceptions, handles them, and ensures cleanup code runs regardless of whether an error occurred.

40 minBy Priygop TeamLast updated: Feb 2026

How Try-Catch Works

When code inside a 'try' block throws an exception (error), Java immediately jumps to the matching 'catch' block instead of crashing the program. The 'finally' block (optional) always runs — whether an exception occurred or not — perfect for cleanup like closing files or database connections.

Try-Catch-Finally Examples

Example
public class ExceptionDemo {
    public static void main(String[] args) {
        // Basic try-catch
        try {
            int result = 10 / 0;  // ArithmeticException!
            System.out.println("Result: " + result);
        } catch (ArithmeticException e) {
            System.out.println("Error: Cannot divide by zero!");
            System.out.println("Details: " + e.getMessage());
        }
        
        // Multiple catch blocks
        try {
            int[] numbers = {1, 2, 3};
            System.out.println(numbers[5]);  // ArrayIndexOutOfBoundsException!
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Error: Index out of bounds!");
        } catch (Exception e) {
            System.out.println("Error: " + e.getMessage());
        }
        
        // Try-catch-finally
        System.out.println("\n=== With Finally ===");
        try {
            System.out.println("Opening resource...");
            String text = null;
            System.out.println(text.length());  // NullPointerException!
        } catch (NullPointerException e) {
            System.out.println("Error: Null value encountered!");
        } finally {
            System.out.println("Cleanup: Resource closed.");  // Always runs!
        }
        
        // Number parsing
        String[] inputs = {"42", "hello", "99", "3.14"};
        for (String input : inputs) {
            try {
                int num = Integer.parseInt(input);
                System.out.println("Parsed: " + num);
            } catch (NumberFormatException e) {
                System.out.println("'" + input + "' is not a valid integer");
            }
        }
        
        System.out.println("\nProgram continues normally!");
    }
}

Try It Yourself: Safe Calculator

Try It Yourself: Safe CalculatorJava
Java Editor
✓ ValidTab = 2 spaces
Java|41 lines|1397 chars|✓ Valid syntax
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Quick Quiz: Try-Catch

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