HashMap的基本用法

HashMap的基本用法
package collection;

import java.util.HashMap;  
import java.util.Iterator;  
import java.util.Set;  
import java.util.Map.Entry;  
  
public class HashMap {  
  
    public static void main(String[] args) {  
          
        HashMap<String, String> hashMap = new HashMap<String, String>();  
        hashMap.put("cn", "中国");  
        hashMap.put("jp", "日本");  
        hashMap.put("fr", "法国");  
          
        System.out.println(hashMap); 
        System.out.println("****");
        System.out.println("cn:" + hashMap.get("cn"));  
        System.out.println(hashMap.containsKey("cn")); 
       
        System.out.println(hashMap.keySet());  
        System.out.println(hashMap.isEmpty());  
          
        hashMap.remove("cn");  
        System.out.println(hashMap);  
        //采用Iterator遍历HashMap  
        Iterator it = hashMap.keySet().iterator();  
        while(it.hasNext()) {  
            String key = (String)it.next();  
            System.out.println("key:" + key);  
            System.out.println("value:" + hashMap.get(key));  
        }  
          
        //遍历HashMap的另一个方法  
        Set<Entry<String, String>> sets = hashMap.entrySet();  
        for(Entry<String, String> entry : sets) {  
            System.out.print(entry.getKey() + ", ");  
            System.out.println(entry.getValue());  
        }  
    }  
}