Java Hashmap Example example code to using Hashmap in Java

HashMap is a Collection Class in package java.util
HashMap store data with key and value for example in below

Example to using HashMap in Java

 package example.util;  
 import java.util.*;  
 public class HashmapExample {  
   public void hashmapExample(){  
     //Create HashMap Object  
     HashMap<String,String> hashmap=new HashMap<String,String>();  
     //Store and Remove data from HashMap  
     hashmap.put("key1", "value1");  
     hashmap.put("key2", "value2");  
     hashmap.put("key3", "value3");  
     String key3=hashmap.remove("key3");  
     //Get Value from HashMap by using Key  
     System.out.println("-- Example for Get Value from HashMap --");  
     System.out.println("Get Hashmap value: "+hashmap.get("key1"));  
     System.out.println("Remove Hashmap value: "+key3);  
     System.out.println("Contains Key Hashmap: "+hashmap.containsKey("key1"));  
     System.out.println("Contains Key Hashmap: "+hashmap.containsKey("key3"));  
     System.out.println("Contains Value Hashmap: "+hashmap.containsValue("value1"));  
     System.out.println("Contains Value Hashmap: "+hashmap.containsValue("value3"));  
     //Loop data from HashMap by keySet and using key to get the Value  
     System.out.println("-- Example for Iterate list from Hash Map --");  
     Iterator<String> it=hashmap.keySet().iterator();  
     while(it.hasNext()){  
       String key=it.next();  
       String value=hashmap.get(key);  
       System.out.println("By Key :Key : "+key+"  Value: "+value);  
     }  
     //Loop data from HashMap by Value List all value no need to using Key  
     it=hashmap.values().iterator();  
     while(it.hasNext()){  
       System.out.println("Value "+it.next());  
     }             
   }  
   public static void main (String args[]){  
     //Test run program in main method  
     HashmapExample hashmap=new HashmapExample();  
     hashmap.hashmapExample();  
   }  
 }  

Output when Run Test Program

-- Example for Get Value from HashMap --
Get Hashmap value: value1
Remove Hashmap value: value3
Contains Key Hashmap: true
Contains Key Hashmap: false
Contains Value Hashmap: true
Contains Value Hashmap: false
-- Example for Iterate list from Hash Map --
By Key :Key : key2   Value: value2
By Key :Key : key1   Value: value1
Value value2
Value value1