Try Catch Exceptions

When your program runs, sometimes unexpected problems occur. These problems are called exceptions. If you don’t handle them, your program will crash.

The try-catch block is how you safely handle exceptions in Java.

Basic Structure

The try-catch block lets you handle exceptions in a safe way. You put the “risky” code inside the try block. If something goes wrong, Java skips the rest of the try and runs the matching catch block instead. This prevents your program from crashing.

try {
    // Code that might cause an exception
} catch (Exception e) {
    // Code that runs if that exception happens
}

• The try block contains the code that might throw an exception.

• If an exception occurs, the catch block runs.

• If no exception occurs, the catch block is skipped.

• You can have multiple catch blocks for different exception types.

• Handling exceptions makes your program more stable.

Note: The Exception class is the parent of all exceptions in Java. If you write catch (Exception e), it will catch any kind of exception. This is useful as a backup, but it’s usually better to catch specific exception types so you know exactly what went wrong.

InputMismatchException

Let’s first look at the InputMismatchException. This exception occurs when we prompt the user for an input, and it does not match the type we are looking for. For example, if we use nextInt() from the Scanner class, and the user enters anything other than a whole number (like a decimal point 3.5 or a letter "abc"), Java will throw this exception and crash the program.

To prevent the program from crashing and receiving the error above, we can import InputMismatchException and use it as the specific exception type we want to catch. That way, the catch block will only run when an InputMismatchException occurs.