Java - Comparing classes?

Question

How can i compare 2 classes?

The following if statement never passes although class is type of MyClass:

public void(Class class) {
   if (class == MyClass.class){

   }
}

Answer 1

To test whether clazz is a (sub) type of MyClass do

MyClass.class.isAssignableFrom(clazz)

From the javadoc for Class.isAssignableFrom

Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter. It returns true if so; otherwise it returns false. If this Class object represents a primitive type, this method returns true if the specified Class parameter is exactly this Class object; otherwise it returns false.

Specifically, this method tests whether the type represented by the specified Class parameter can be converted to the type represented by this Class object via an identity conversion or via a widening reference conversion. See The Java Language Specification, sections 5.1.1 and 5.1.4 , for details.

So

Object.class.isAssignableFrom(String.class)

is true because each String is also an Object but

String.class.isAssignableFrom(Object.class)

is false because not all Objects are Strings.

---

The name "isAssignableFrom" comes from the fact that,

Class1 x = (Class2) null;

is only legal when

Class1.class.isAssignableFrom(Class2.class)

I.e., we can assign a field or variable with static type Class1 a value that comes from an expression whose static type is Class2.