java.util.TreeSet.addAll() Method

Description

The addAll(Collection c) method is used to add all of the elements in the specified collection to this set.

Declaration

Following is the declaration for java.util.TreeSet.addAll() method.

public boolean addAll(Collection c)

Parameters

• c--These are the elements to be added.

Return Value

The method call returns true if this set changed as a result of the call.

Exception

• ClassCastException--This exception is thrown if the elements provided cannot be compared with the elements currently in the set.

• NullPointerException--This exception is thrown if the specified collection is null.

Example

The following example shows the usage of java.util.TreeSet.addAll() method.

package com.tutorialspoint;

import java.util.Iterator;
import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {
     // creating a TreeSet 
     TreeSet <Integer>treeone = new TreeSet<Integer>();
     TreeSet <Integer>treetwo = new TreeSet<Integer>();
     
     // adding in the treeone
     treeone.add(12);
     treeone.add(13);
     treeone.add(14);
     
     // adding in the treetwo
     treetwo.add(15);
     treetwo.add(16);
     treetwo.add(17);  
     
     // adding treetwo to treeone
     treeone.addAll(treetwo);
     
     // create an iterator
     Iterator iterator;
     iterator = treeone.iterator();
     
     // displaying the Tree set data
     System.out.print("Tree set data: ");     
     while (iterator.hasNext()){
        System.out.print(iterator.next() + " ");
     }
   }    
}

Let us compile and run the above program, this will produce the following result.

Tree set data: 12 13 14 15 16 17