Java Exception Propagation

In this Java article we want to learn about Java Exception Propagation, so in in Java we can say that exception propagation is the process of passing an exception from one method to another until it is caught and handled by an appropriate catch block. exception propagation is an important concept in Java programming, because it allows us to handle exceptions.

How Exception Propagation Works in Java

When an exception occurs in a method, it can be handled in two ways, first way is this that the method can catch and handle the exception or another way is this that it can throw an exception to the calling method using throw keyword. if exception is not caught and handled in the method, it will be propagated to the calling method until it is caught and handled by an appropriate catch block.

This is an example of how exception propagation works in Java.

public class ExceptionPropagationDemo {
    public static void main(String[] args) {
        try {
            method1();
        } catch (Exception e) {
            System.out.println("Exception caught: " + e.getMessage());
        }
    }

    public static void method1() throws Exception {
        method2();
    }

    public static void method2() throws Exception {
        method3();
    }

    public static void method3() throws Exception {
        throw new Exception("Exception in method3");
    }
}

public class ExceptionPropagationDemo {

public static void main(String[] args) {

try {

method1();

} catch (Exception e) {

System.out.println("Exception caught: " + e.getMessage());

}

public static void method1() throws Exception {

method2();

}

public static void method2() throws Exception {

method3();

}

public static void method3() throws Exception {

throw new Exception("Exception in method3");

}

In the above example, method3() throws an exception. and you can see that the exception is not caught and handled in method3(), it is propagated to method2(). and also because the exception is not caught and handled in method2(), it is propagated to method1(). and finally exception is caught and handled in the try catch block in the main() method.

In Java we can handle exceptions using try catch blocks. when an exception is thrown in try block, it is caught by a catch block that matches the type of the exception. catch block handles the exception and the program continues to execute normally.

public class ExceptionHandlingDemo {
    public static void main(String[] args) {
        try {
            // code that can throw an exception
        } catch (ExceptionType1 e1) {
            // handle ExceptionType1
        } catch (ExceptionType2 e2) {
            // handle ExceptionType2
        } catch (Exception e) {
            // handle all other exceptions
        } finally {
            // finally block
        }
    }
}

public class ExceptionHandlingDemo {

public static void main(String[] args) {

try {

// code that can throw an exception

} catch (ExceptionType1 e1) {

// handle ExceptionType1

} catch (ExceptionType2 e2) {

// handle ExceptionType2

} catch (Exception e) {

// handle all other exceptions

} finally {

// finally block

}

In the above example we have used a try block to execute code that can throw an exception. we have used multiple catch blocks to handle different types of exceptions. we can also use a catch block with Exception class to handle all other exceptions that are not caught by the other catch blocks. and finally we can use a finally block to execute code that needs to be executed regardless of whether an exception is thrown or not.