Java Collection add() method
The add() method of Java Collection Interface inserts the specified element in this Collection. It returns a Boolean value ‘true’, if it succeeds to insert the element in the specified collection else it returns ‘false’.
Syntax
Parameters
The parameter ‘e’ represents the element to be added in the Collection.
Return
The add() method returns a Boolean value ‘true’, if the specified element is not null and this collection has successfully changed as a result of the call.
Throws
The add() method throws:
UnsupportedOperationException – if the add operation is not supported by this collection
ClassCastException- if the class of the specified element prevents it from being added to this collection.
NullPointerException- if the specified element is null and this collection does not allow null elements
IllegalArgumentException- if some property of the element prevents it from being added to this collection
IllegalStateException- if the element cannot be inserted at this time due to some insertion restrictions
Example 1
Output:
The elements in Collection : [34, 12, 45]
Example 2
Output:
The elements in Collection : [Anurag, Dhruv, Prena, Bajaj]
Example 3
Output:
The elements in Collection : [12, null, 0, 5]
Example 4
Output:
Exception in thread "main" java.lang.NullPointerException at java.util.concurrent.ConcurrentLinkedQueue.checkNotNull(ConcurrentLinkedQueue.java:920) at java.util.concurrent.ConcurrentLinkedQueue.offer(ConcurrentLinkedQueue.java:327) at java.util.concurrent.ConcurrentLinkedQueue.add(ConcurrentLinkedQueue.java:297) at com.tutorAspire.JavaCollectionAddExample4.main(JavaCollectionAddExample4.java:13)
If any of the specified element in this queue is null, it will give NullPointerException as described above.