How to access a static method via a class reference

Question

class A {     public static void foo() {} }  class B {     public static void foo() {} } 

I have Class clazz = A.class; or B.class;

How do I access this via "clazz" assuming it might be assigned either 'A' or 'B'

Answer 1

It is only possible to access those methods using reflection. You cannot reference a class directly, only an instance of type Class.

To use reflection to invoke methodname(int a, String b):

Method m = clazz.getMethod("methodname", Integer.class, String.class); m.invoke(null, 1, "Hello World!"); 

See Class.getMethod() and Method.invoke()

You may want to think about your design again, to avoid the need to dynamically call static methods.

Answer 2

You can invoke a static method via reflection like this :

Method method = clazz.getMethod("methodname", argstype); Object o = method.invoke(null, args); 

Where argstype is an array of arguments type and args is an array of parameters for the call. More informations on the following links :

• getMethod()
• invoke()

In your case, something like this should work :

Method method = clazz.getMethod("foo", null); method.invoke(null, null); // foo returns nothing