Java Generic Class

Java Generic Class

public interface EXPeekableQueue<E extends Comparable<E>>>{
public void enqueue(E e);
}
public interface EXammutableQueue<E>{
public EXammutableQueue<E> enqueue(E e);
public E peek();
}
What exactly do this Syntax means ? I am having trouble understanding Java
Generic class. Can someone send me a link to a good tutorial or pdf file ?
Thankyou!!