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Passing an inline constructed class as a class argument to a method

I need to call the following method.

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

For the argument, cls

I need to pass a class that only overrides one method Bar

.

I want to know if there is a way to write the definition of my new inline class in the above call without writing the new class in a separate file that extends Bar.

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2 answers


Three options:

  • You can create a nested class in the same class where you want to use this code; no need for a new file

    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);
}

    Declaring a class inside a method like this is very unusual, mind you.

  • You can use an anonymous inner class, 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 an object Class

, of course, which is not perfect.

Personally, I would choose the first option.

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Yes, you can just declare an anonymous class and use a method on it getClass()

:



foo(new Bar() {
    //implement your method here
}.getClass());
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