How to catch multiple exceptions

Short answer

Add several catch blocks — the first matching one runs:

void parseAndPrint(String[] parts, int index) {
    try {
        int value = Integer.parseInt(parts[index]);
        IO.println("Value: " + value);
    } catch (NumberFormatException e) {
        IO.println("Not a number: " + parts[index]);
    } catch (ArrayIndexOutOfBoundsException e) {
        IO.println("No element " + index);
    }
}
 
void main() {
    String[] parts = {"10", "abc"};
    parseAndPrint(parts, 0);
    parseAndPrint(parts, 1);
    parseAndPrint(parts, 5);
}

Output:

Value: 10
Not a number: abc
No element 5

One handler for several types

If the reaction is the same, list the types separated by |:

void main() {
    for (String input : List.of("42", "x", "")) {
        try {
            IO.println(100 / Integer.parseInt(input.isEmpty() ? "0" : input));
        } catch (NumberFormatException | ArithmeticException e) {
            IO.println("Bad input: " + e.getClass().getSimpleName());
        }
    }
}

Output:

2
Bad input: NumberFormatException
Bad input: ArithmeticException

Block order

Put more specific exceptions before general ones. Otherwise the compiler reports that a block is unreachable:

void main() {
    try {
        Integer.parseInt("x");
    } catch (Exception e) {
        IO.println("general");
    } catch (NumberFormatException e) {
        IO.println("number");
    }
}

Output:

Main.java:6: error: exception NumberFormatException has already been caught

finally

The finally block always runs — after successful code and after an exception:

void main() {
    try {
        IO.println("working");
        throw new IllegalStateException("boom");
    } catch (IllegalStateException e) {
        IO.println("caught " + e.getMessage());
    } finally {
        IO.println("cleanup");
    }
}

Output:

working
caught boom
cleanup

Common mistake

Catching Exception and silently ignoring it. The error disappears, and the program keeps working with bad data:

void main() {
    int total = 0;
    for (String s : List.of("5", "five", "7")) {
        try {
            total += Integer.parseInt(s);
        } catch (Exception e) {
        }
    }
    IO.println(total);
}

Output:

At the very least, log the error or tell the user which data was skipped.

Thanks for reading!

Short answer

One handler for several types

Block order

finally

Common mistake

Functions used in this recipe

Thanks for reading!