TreeSet addAll() method in java

Let’s learn TreeSet addAll() method in java.

TreeSet addAll() method in java

addAll(Collection<? extends E> c) method of TreeSet class adds all of the elements in the specified collection to this set.

Syntax:

public boolean addAll(Collection<? extends E> c)

Parameters:

c collection containing elements to be added to this set.

Returns:

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

Throws:

ClassCastException – if the elements provided cannot be compared with the elements currently in the set.

NullPointerException – if the specified collection is null or if any element is null and this set uses natural ordering, or its comparator does not permit null elements.

Now let’s see example on TreeSet addAll(Collection<? extends E> c) method.

import java.util.Iterator;
import java.util.TreeSet;
public class TreeSetAddAllMethodExample
{
   public static void main(String[] args)
   {
      TreeSet<Integer> ts1 = new TreeSet<Integer>();
      TreeSet<Integer> ts2 = new TreeSet<Integer>();
      // add in TreeSet ts1
      ts1.add(23);
      ts1.add(24);
      ts1.add(25);
      // add in TreeSet ts2
      ts2.add(26);
      ts2.add(27);
      ts2.add(28);
      // add ts2 to ts1
      ts1.addAll(ts2);
      // create an iterator
      Iterator<Integer> iterate = ts1.iterator();
      // displaying the Tree set data
      System.out.print("TreeSet values: ");
      while(iterate.hasNext())
      {
         System.out.print(iterate.next() + " ");
      }
   }
}

Output:

TreeSet values: 23 24 25 26 27 28