Try-Catch ブロック

In Java, runtime errors are handled using Exceptions. Exception handling allows us to intercept anomalous conditions and prevent the program from crashing.

The try-catch structure

To handle a potential exception, we enclose the risky code in a try block. If an error occurs inside the try block, the JVM stops executing it and searches for a matching catch block to handle the exception.

try {
    int result = 10 / 0; // Generates ArithmeticException
    System.out.println("This will not be printed");
} catch (ArithmeticException e) {
    System.out.println("Arithmetic error occurred: " + e.getMessage());
}

The finally block

The finally block is optional and is always executed, regardless of whether an exception was thrown. It is ideal for releasing resources or performing cleanup operations.

try {
    System.out.println("Executing logic");
} catch (Exception e) {
    System.out.println("Error");
} finally {
    System.out.println("This block is always executed");
}

Throwing Exceptions: throw

We can intentionally throw an exception using the throw keyword followed by a new instance of an exception class.

public static void checkScore(int score) {
    if (score < 0 || score > 100) {
        throw new IllegalArgumentException("Score must be between 0 and 100");
    }
}

Try it yourself