meet it

Many problems, many catches, and a that always runs.

One try can have several catch blocks, one for each kind of problem. Java checks them from the top and runs only the first that matches. Dividing a whole number by zero, for example, gives an .

A finally block goes at the very end, and it always runs: after a clean try, after a catch, even while an uncaught exception is on its way out. It is the place to tidy up, like switching off the lights as you leave.

public class Main {
    static void share(String sweets, int friends) {
        try {
            int each = Integer.parseInt(sweets) / friends;
            System.out.println("Each friend gets " + each);
        } catch (NumberFormatException e) {
            System.out.println("That is not a number of sweets");
        } catch (ArithmeticException e) {
            System.out.println("Nobody to share with");
        } finally {
            System.out.println("Bag closed");
        }
    }
    public static void main(String[] args) {
        share("12", 4);
        share("lots", 4);
        share("12", 0);
    }
}

finally is the right home for goodbyes, saving work and closing things you opened.

guess first

When does finally run? Make a guess.

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

public class Main {
    static String check(String text) {
        try {
            return "Got " + Integer.parseInt(text);
        } catch (NumberFormatException e) {
            return "Not a number";
        } finally {
            System.out.println("Checked " + text);
        }
    }
    public static void main(String[] args) {
        System.out.println(check("5"));
        System.out.println(check("five"));
    }
}

your turn

Your turn. Split the bill.

On line 5, fill in the exception that dividing by zero gives. On line 8, write a goodbye message of your own. Then press run.

Your code

output

press run to see what happens

fix it

The lights were left on. Fix it!

Broken code to fix

output

press run to see what happens

After the second party goes wrong, the lights stay on. Why is line 7 skipped?
When parseInt fails, Java jumps to catch and skips the rest of try. A line that must always run needs its own block.
Move line 7 into a finally { } block after the catch, then press run.

nailed it

you handled every outcome. :D

Several catch blocks handle different problems, first match first.
finally always runs, error or not.
Use finally for tidying up.

new words in your collection

ArithmeticException
finally

This lesson isn’t saved. A free account remembers every lesson you finish.

Many problems, many catches, and a finally that always runs.

When does finally run? Make a guess.

Your turn. Split the bill.

The lights were left on. Fix it!

you handled every outcome. :D

Many problems, many catches, and a that always runs.