Java – pass the inline constructed class to the method as a class parameter

I need to call the following method

void foo(Class<? extends Bar> cls);

For the CLS parameter, I need to pass a class that only overrides a single method of bar

I wonder if there is a way to write the inline definition of my new class in the above call itself without writing the new class in a separate file extending the bar

Solution

Three options:

>You can create nested classes in the same class that you want to use this code; No new files are required

public static void doSomething() {
    foo(Baz.class);
}

private static class Baz extends Bar {
    // Override a method
}

>You can declare a named class in a method:

public static void doSomething() {
    class Baz extends Bar {
        // Override a method
    }
    foo(Baz.class);
}

It is very unusual to declare a class in such a method. Please note. > You can use anonymous internal classes, but then call getClass ():

public static void doSomething() {
    foo(new Bar() {
        // Override a method
    }.getClass());
}

The last option creates an instance of an anonymous inner class just to get the class object, which is certainly not ideal

Personally, I may choose the first option