diff b/w PriorityQueue "add" and "offer" methods

[Ameen khan]

What is the diff b/w PriorityQueue "add" and "offer" methods??

[Priyam Srivastava]

Originally posted by Ameen khan:
What is the diff b/w PriorityQueue "add" and "offer" methods??

I looked into the Java specifiaction regarding these two methods and difference(if any) wasn't clearly mentioned there also. This is what they say::

boolean add(E o)
Adds the specified element to this queue

boolean offer(E o)
Inserts the specified element into this priority queue.

I tried to use both of them in the same program :

  
import java.util.*;
 
class PQueue {
public static void main(String[] args) {
PriorityQueue<Integer> pq = new PriorityQueue<Integer>();
pq.add(2);
pq.offer(1);
Iterator<Integer> it = pq.iterator();
while(it.hasNext()) {
System.out.println(it.next());
}
}
}

Output ::
1
2

which is not much different what one expected. So I guess no difference b/w those two methods..

[Yeming Hu]

Quoted from Java API spe:
boolean add(E e)

Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.

boolean offer(E e)

Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted queue, this method is generally preferable to add(E), which can fail to insert an element only by throwing an exception.

Refer to Queue API
[ August 08, 2007: Message edited by: Yeming Hu ]