Sample Of Hash ( One of Type Collection In Java )

A Set is a Collection that contains unique elements (i.e., no duplicate elements). 
The collections framework contains several Set implementations, 
including HashSet and TreeSet. HashSet stores its elements in a hash table, and TReeSet stores its elements in a tree.
U can uses a HashSet to remove duplicate strings from a List. Recall that both List and Collection are generic types, 
so creates a List that contains String objects, and passes a Collection of Strings to method printNonDuplicates.

import java.util.List;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.Collection;

public class SetTest   {
     private static final String colors[] = { "red", "white", "blue",
       "green", "gray", "orange", "tan", "white", "cyan",
       "peach", "gray", "orange" };
     // create and output ArrayList
  public SetTest()  {
      List list = Arrays.asList( colors );
      System.out.printf( "ArrayList: %s\n", list );
      printNonDuplicates( list );
  } 

    private void printNonDuplicates( Collection collection ){
      // create a HashSet                                     
      Set set = new HashSet( collection );
      System.out.println( "\nNonduplicates are: " );

        // Model Out Print From Java 6               
      for ( String s : set )
         System.out.printf( "%s ", s );
      System.out.println();
  } 

    public static void main( String args[] )     {
      new SetTest();
  } 
}

Result Is :

ArrayList: [red, white, blue, green, gray, orange, tan, white, cyan, peach, gray, orange]
Nonduplicates are:
red cyan white tan gray green orange blue peach