What is the difference between the add and offer methods in a Queue in Java?

Question

Take the PriorityQueue for example http://java.sun.com/j2se/1.5.0/docs/api/java/util/PriorityQueue.html#offer(E)

Can anyone give me an example of a Queu

Answer 1

from the source code in jdk 7 as follow:

public boolean add(E e) {
    if (offer(e))
        return true;
    else
        throw new IllegalStateException("Queue full");
}

we can easily know that the add function will return true when successfully add a new element into the queue, but throw a exception when failed .