Java Exception Handling

Java exception handling

Created By: chatGPT

In Java, exception handling is a powerful mechanism that allows developers to manage runtime errors to maintain the normal flow of application execution. Exceptions are events that disrupt the normal flow of program execution. Java provides a robust framework for handling these exceptions through the use of try, catch, and finally blocks.

try {
    // code that may throw an exception
} catch (ExceptionType e) {
    // code to handle the exception
} finally {
    // code that executes regardless of an exception being thrown
}

The try block contains code that might throw an exception. If an exception occurs, the control is passed to the corresponding catch block that handles that specific type of exception. The finally block, if present, is executed after the try-catch blocks, regardless of whether an exception occurred or not. This block is often used for cleanup tasks such as closing database connections or files.

try {
    int[] array = {1, 2, 3};
    System.out.println(array[5]); // This will throw an ArrayIndexOutOfBoundsException
} catch (ArrayIndexOutOfBoundsException e) {
    System.out.println("Array index is out of bounds!");
} finally {
    System.out.println("This will always execute.");
}

Java also allows creating custom exceptions by extending the Exception class. This is helpful when you want to define specific error conditions related to your application. To create a custom exception, you need to define a class that extends Exception and provide at least one constructor that calls the super class constructor.

public class MyCustomException extends Exception {
    public MyCustomException(String message) {
        super(message);
    }
}

To throw this custom exception, you can use the throw statement within a method. You should also declare that the method can throw this exception by using the throws keyword in the method signature.

public void myMethod() throws MyCustomException {
    throw new MyCustomException("This is a custom exception!");
}

Finally, a good practice in exception handling is to catch specific exceptions first before catching more general ones. This prevents you from unintentionally masking exceptions that you meant to handle specifically. Here is an example:

try {
    // some code
} catch (NullPointerException e) {
    // handle NullPointerException
} catch (Exception e) {
    // handle any other exceptions
}