In this tutorial we can see how to use Collections in java program. Now we can see uses of List, Set, SortedSet, LinkedHashSet, Map, LinkedHashMap.

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;

public class CollectionExample 
 {
  public static void main(String[] args) 
   {
    List l = new LinkedList();
    l.add("List:angel");
    l.add("schildt");
    l.add("mathew");
    l.add("schildt");
    print(l); 
  
    Set s = new HashSet();
    s.add("set:rose");
    s.add("schildt");
    s.add("mathew");
    s.add("schildt");
    print(s); 

    SortedSet ss = new TreeSet();
    ss.add("set:jasmine");
    ss.add("schildt");
    ss.add("mathew");
    ss.add("schildt");
    print(ss); 

    LinkedHashSet sss = new LinkedHashSet();
    sss.add("set:winslet");
    sss.add("schildt");
    sss.add("mathew");
    sss.add("schildt");
    print(sss); 

    Map m1 = new HashMap();
    m1.put("map", "HashMap");
    m1.put("schildt", "java2");
    m1.put("mathew", "Hyden");
    m1.put("schildt", "java2s");
    print(m1.keySet()); 
    print(m1.values()); 

    SortedMap sm = new TreeMap();
    sm.put("map", "TreeMap");
    sm.put("schildt", "java2");
    sm.put("mathew", "Hyden");
    sm.put("schildt", "java2s");
    print(sm.keySet()); 
    print(sm.values());
 
    LinkedHashMap lm = new LinkedHashMap();
    lm .put("map", "LinkedHashMap");
    lm .put("schildt", "java2");
    lm .put("mathew", "Hyden");
    lm .put("schildt", "java2s");
    print(lm .keySet()); 
    print(lm .values()); 
  }

  static void print(Collection coll) 
  {
    Iterator iter = coll.iterator();
    while (iter.hasNext()) 
    {
      String elem = (String) iter.next();
      System.out.print(elem + " ");
    }
    System.out.println();
  }

}

Output:

List:angel schildt mathew schildt
set:rose schildt mathew
schildt set:jasmine mathew
set:winslet schildt mathew
schildt mathew map
java2 Hyden HashMap
schildt mathew map
java2 Hyden TreeMap
map schildt mathew
LinkedHashMap java2 Hyden

2010-01-01

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