UndeclaredThrowableException

The UndeclaredThrowableException is a runtime exception that is thrown when an invoked method throws a checked exception that is not declared in the method's throws clause. This exception is a wrapper exception that wraps the actual checked exception and provides a way to handle it at runtime.

Here is an example of how this exception can be thrown:

public interface MyInterface {
    void myMethod() throws IOException;
}

public class MyClass implements MyInterface {
    @Override
    public void myMethod() throws IOException {
        throw new IOException("IOException occurred");
    }
}

public class Main {
    public static void main(String[] args) {
        MyInterface myObject = new MyClass();

        try {
            myObject.myMethod();
        } catch (Exception e) {
            throw new UndeclaredThrowableException(e);
        }
    }
}

In the above example, the myMethod() of the MyClass throws an IOException, which is not declared in the MyInterface's throws clause. In the Main class, when invoking the myMethod() through the myObject reference, the IOException is thrown. Since it is a checked exception and not declared in the throws clause of the main() method, it is wrapped in an UndeclaredThrowableException and re-thrown.

The UndeclaredThrowableException can be caught and processed to handle the actual exception. It provides methods like getUndeclaredThrowable() to retrieve the wrapped exception and getCause() to get the cause of the exception.

It is important to note that the UndeclaredThrowableException should be used with caution, as it can hide the actual exception and make it harder to debug and handle the exception properly. It is generally a good practice to declare the checked exceptions in the throws clause to ensure proper handling and documentation