Question

Are anonymous inner classes private by default? Can I make them public?

I need to access methods by reflection.

Answer 1

You can access an anonymous inner class’ methods with reflection. See getDeclaredMethods().
Remember to call setAccessible(true) on the Method in order to avoid an IllegalAccessException.

Object testObject = new Object() {
    private void testMe() { 
        System.out.println("testme");
    }
};
Method m = testObject.getClass().getDeclaredMethod("testMe");
m.setAccessible(true);
m.invoke(testObject); // prints out "testme"

Also notice that if there’s a SecurityManager this won’t be possible, see What is the security risk of object reflection?

Warning: Take into account that anonymous inner classes are kind of disposable class definitions. Once used, you’ll never need them elsewhere again. Just like @PéterTörök said, it’s hard to tell without more context on your problem, but, if you’ve got control over that class, it would probably be better to deanonymize that class (making a private inner class, or even public), and expose that method to the classes that need it.