Iterate Map 

The following example shows creating a Map and iterating its entries. HashMap and Hashtable are two implementations of Map interface. Hashtable is synchronized where as HashMap is not. Map provides the following APIs,

public int size();
 - Returns the number of entries in the Map.
 
public boolean isEmpty();
 - Returns true if the Map contains more than one entry otherwise returns false. 
 
public Set keySet();
 - Returns all keys in the Map as a Set.

File Name  :   com/bethecoder/tutorials/utils/maps/Iterate.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.utils.maps; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class Iterate {   /**    * @param args    */   public static void main(String[] args) {     Map<Integer, String> numMap = new HashMap<Integer, String>();     numMap.put(new Integer(1), "ONE");     numMap.put(new Integer(2), "TWO");     numMap.put(new Integer(3), "THREE");          System.out.println("Map Size : " + numMap.size() + " " + numMap);     System.out.println("Is Map Empty ? : " + numMap.isEmpty());     System.out.println();          Iterator<Integer> keys = numMap.keySet().iterator();     Integer key = null;     String value = null;          while (keys.hasNext()) {       key = keys.next();       value = numMap.get(key);              System.out.println(key + "=" + value);     }   } }

Map Size : 3 {1=ONE, 2=TWO, 3=THREE}
Is Map Empty ? : false

1=ONE
2=TWO
3=THREE