Can an interface extend another interface in Java?

Yes. Just remember that you should implement the methods in both interfaces.

Example in Java source code link1, link2:

public interface List<E> extends Collection<E> {

}

public interface Collection<E> extends Iterable<E> {

}

In conclusion, ref

An interface can extend multiple interfaces.

A class can implement multiple interfaces.

However, a class can only extend a single class.

a special case

interface A
{
    void test();
}

interface B 
{
    void test();
}

class C implements A, B
{
    @Override
    public void test() {

    }
}

Well, a single implementation works for the both methods. This implementation works no problem.