Get the interface name from the implementation class

Question

Example :

List<String> list = new ArrayList<String>();
//This would give me the class name for the list reference variable.
list.getClass().getSimpleName();

I want to get the Interface name from the list reference variable. Is there any way possible to do that?

Solution 1

Using Reflection you can invoke the Class.getInterfaces() method which returns an Array of Interfaces that your class implements.

list.getClass().getInterfaces()[0];

To get just the name

list.getClass().getInterfaces()[0].getSimpleName();

Solution 2

Class  aClass = ... //obtain Class object. 
Class[] interfaces = aClass.getInterfaces();

Comments

[Guillaume]

You may also want to recurse on the interfaces extended by these interfaces.

[PermGenError]

@Guillaume good point, they would be class implementing order, for instance interface[0] would be java.util.List and interface[1] would be java.util.RandomAccess

[Guillaume]

And if you want to get the Collection interface you have to call getInterface() on the interfaces returned by the first call.