Passing class as argument to a method

Question

I'm doing the following to establish the public methods of the class TestA.

List<String> strings = new ArrayList<String>();
Method[] methods = TestA.class.getDeclaredMethods();
for(Method method : methods) 
{
  if(Modifier.isPublic(method.getModifiers())) 
  {         
    strings.add(method.getName());
  }
}

I also need to do the same thing for TestB , TestC etc so I'd like to have a function which takes a class name and returns a String array of the public methods. How can I do this?

If I have an Object parameter, I will have to create an instance of each Class before I send them to the function. I wish to avoid this.

Answer 1

It sounds like you want:

public static List<String> getPublicDeclaredMethods(Class<?> clazz) {
    List<String> strings = new ArrayList<String>();
    Method[] methods = clazz.getDeclaredMethods();
    for(Method method : methods)  {
        if(Modifier.isPublic(method.getModifiers())) {
            strings.add(method.getName());
        }
    }
    return strings;
}

Then call it with:

List<String> names = getPublicDeclaredMethods(TestA.class);

You should also consider using Class.getMethods which only returns public methods anyway - but returns ones inherited from superclasses.

Answer 2

You can pass java.lang.Class instance it self , like shown below

 public void introspectClass(Class cls){
    List<String> strings = new ArrayList<String>();
    Method[] methods = cls.getDeclaredMethods();
    for(Method method : methods) 
    {
      if(Modifier.isPublic(method.getModifiers())) 
      {         
        strings.add(method.getName());
      }
    }
    }