Java Academy · Lesson

try/catch/finally

Learn to use try, catch, and finally to handle runtime errors safely.

Lesson 1 of 38 steps

try/catch/finally is a free Java Academy lesson on CoddyKit. This is lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, and your progress syncs across the web and the CoddyKit app. The Java Academy course includes 3 lessons in total.

Intro

Programs sometimes hit errors: invalid input, missing files, divide by zero. Exceptions are Java's way to handle them without crashing.

try/catch overview

Wrap risky code in a try block. If an exception occurs, control jumps to a matching catch. This lets you handle errors gracefully.

Code: simple try/catch

This code catches an ArithmeticException and prints a friendly message instead of crashing.

public class Main {
  public static void main(String[] args) {
    try {
      int x = 10 / 0; // risky division
      System.out.println("Result=" + x);
    } catch (ArithmeticException e) {
      System.out.println("Cannot divide by zero!");
    }
  }
}

Multiple catches

You can stack multiple catch blocks to handle different exception types separately. Order matters: put specific ones before general ones.

Code: multiple catch

The NullPointerException is caught by its specific block. Each type can be handled differently.

public class Main {
  public static void main(String[] args) {
    try {
      String s = null;
      System.out.println(s.length()); // NullPointerException
    } catch (ArithmeticException e) {
      System.out.println("Math error");
    } catch (NullPointerException e) {
      System.out.println("Null reference error");
    }
  }
}

Code: finally block

The finally block executes whether or not an exception occurs. Use it for cleanup like closing files.

public class Main {
  public static void main(String[] args) {
    try {
      int[] arr = {1,2};
      System.out.println(arr[5]); // ArrayIndexOutOfBounds
    } catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Bad index!");
    } finally {
      System.out.println("Finally block always runs");
    }
  }
}

finally check

Quick check: What is the purpose of the finally block?

Answer it in the interactive lesson

Recap

Recap: try handles risky code, catch reacts to errors, and finally runs every time for cleanup.

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Frequently Asked Questions

Is the “try/catch/finally” lesson free?

Yes — the full text of “try/catch/finally” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO. The Java Academy course includes 3 lessons in total.

What will I learn in “try/catch/finally”?

Learn to use try, catch, and finally to handle runtime errors safely. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Java Academy?

No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.

How long does the “try/catch/finally” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Java Academy lesson?

Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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