Exception Handlers

Exception Handlers in Java are constructs used to handle exceptions that occur during the execution of a program. The primary way to handle exceptions is by using try, catch, and finally blocks.

try-catch Block

The try block contains code that might throw an exception. The catch block handles the exception type declared in its parameter.

try {
    int[] arr = new int[5];
    arr[10] = 50; // This will throw ArrayIndexOutOfBoundsException
} catch (ArrayIndexOutOfBoundsException e) {
    System.out.println("Caught exception: " + e);
}

Multiple catch Blocks

You can catch different types of exceptions separately.

try {
    String str = null;
    System.out.println(str.length());
} catch (NullPointerException e) {
    System.out.println("NullPointerException caught");
} catch (Exception e) {
    System.out.println("General Exception caught");
}

finally Block

The finally block is executed whether an exception is handled or not.

try {
    int result = 25 / 5;
} catch (ArithmeticException e) {
    System.out.println("Caught ArithmeticException");
} finally {
    System.out.println("Finally block executed");
}

Nested try-catch

You can nest try-catch blocks inside other try blocks.

try {
    try {
        int data = 50 / 0;
    } catch (ArithmeticException e) {
        System.out.println("Inner catch: " + e);
    }
} catch (Exception e) {
    System.out.println("Outer catch: " + e);
}

Best Practices

Catch specific exceptions before general ones.
Avoid catching Throwable unless absolutely necessary.
Use finally for cleanup operations like closing resources.