Java Collection Tutorial - Java Collections.singleton(T o)

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Syntax

Collections.singleton(T o) has the following syntax.

public static <T> Set <T> singleton(T o)

Example

In the following code shows how to use Collections.singleton(T o) method.

/* w  w w  .j  a v a  2 s.c o m*/
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class Main {
   public static void main(String args[]) {
      String init[] = { "One", "Two", "Three", "One", "Two", "Three" };
      
      // create two lists
      List<String> list1 = new ArrayList<String>(Arrays.asList(init));
      List<String> list2 = new ArrayList<String>(Arrays.asList(init));
      
      // remove from list1
      list1.remove("One");
      System.out.println("List1 value: "+list1);
      
      // remove from list2 using singleton
      list2.removeAll(Collections.singleton("One"));       
      System.out.println("The SingletonList is :"+list2);
   }
}

The code above generates the following result.

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