How to handle exceptions

Updated September 2026 · Beginner-friendly guide

Catch a specific exception

Put risky code in try and catch only exceptions the program can handle meaningfully.

try {
    int number = Integer.parseInt("abc");
    System.out.println(number);
} catch (NumberFormatException error) {
    System.out.println("Enter a whole number.");
}

Use finally

A finally block runs whether the try succeeds or throws, making it suitable for necessary cleanup.

try {
    System.out.println("Working");
} finally {
    System.out.println("Cleanup");
}

Throw an exception

Reject invalid arguments close to the method boundary and include a useful message.

static void setAge(int age) {
    if (age < 0) {
        throw new IllegalArgumentException("age cannot be negative");
    }
}

Do not hide failures

Catch the most specific useful exception type.
Do not leave catch blocks empty.
Log or display enough context to understand the failure.
Use try-with-resources for closeable files and streams.