Java nested try block exception handling

When a try-catch block is present in another try block then it is called the nested try-catch block. Each time a try block does not have a catch handler for a particular exception, then the catch blocks of the parent try block are inspected for that exception if the match is found that that catch block executes.

Example 1:

public class NestedTryCatchExmple {
    public static void main(String args[]) {
        // main try-block
        try {
            // try-block level 1
            try {

                int arr[] = { 1, 2, 3, 4 };
                // the below statement throws ArrayIndexOutOfBoundsException
                System.out.println(arr[10]);
            } catch (ArithmeticException e) {
                System.out.print("Arithmetic Exception");
                System.out.println(" handled in try-block level 1");
            }

        } catch (ArithmeticException e) {
            System.out.print("Arithmetic Exception");
            System.out.println(" handled in main try-block");
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.print("ArrayIndexOutOfBoundsException");
            System.out.println(" handled in main try-block");
        } catch (Exception e) {
            System.out.print("Exception");
            System.out.println(" handled in main try-block");
        }
    }
}

The above code will throw an ArrayIndexOutOfBoundsException which will be handled in the main try-catch block.

Output

ArrayIndexOutOfBoundsException handled in main try-block

Example 2:

public class NestesTryCatchExamples {
    public static void main(String args[]) {
        // Parent try block
        try {
            // Child try block1
            try {
                System.out.println("Inside Child try block1");
                int b = 45 / 0;
                System.out.println(b);
            } catch (ArithmeticException e1) {
                System.out.println("Exception: e1");
            }
            // Child try block2
            try {
                System.out.println("Inside Child try block2");
                int b = 45 / 0;
                System.out.println(b);
            } catch (ArrayIndexOutOfBoundsException e2) {
                System.out.println("Exception: e2");
            }
        } catch (ArithmeticException e3) {
            System.out.println("Arithmetic Exception");
            System.out.println("Inside parent try catch block");
        } catch (ArrayIndexOutOfBoundsException e4) {
            System.out.println("ArrayIndexOutOfBoundsException");
            System.out.println("Inside parent try catch block");
        } catch (Exception e5) {
            System.out.println("Exception");
            System.out.println("Inside parent try catch block");
        }
    }
}

Output

Inside Child try block1
Exception: e1
Inside Child try block2
Arithmetic Exception
Inside parent try catch block

 

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