java - Difference between add(E e) and offer(E e) of ArrayDqueue Class -

hi used add , offer add element in last pace. both returning boolean , both not throw exception apart npe.

 public class arraydequedemo {    public static void main(string[] args) {       // create arraydeque elements.     arraydeque<integer> deque = new arraydeque<>();     deque.add(10);     deque.offer(30);     }  } 

both add element in last place returning boolean.

java implementation

//for add , offer both    public void addlast(e e) {     if (e == null)         throw new nullpointerexception();     elements[tail] = e;     if ( (tail = (tail + 1) & (elements.length - 1)) == head)         doublecapacity(); } 

the 2 methods equivalent.

the reason both exist the java.util.queue interface specifies both.

the reason java.util.queue specifies both implementation of java.util.queue allowed implement capacity restrictions, , 2 methods specified behave differently in case adding element violate restriction; specifically, add(...) specified throw illegalstateexception in case, whereas offer(...) returns false.

java.util.arraydequeue, however, not implement capacity restrictions, situation not arise it, distinction not apply.