Java中关于HashMap的使用和遍历

package com.pb.collection;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import java.util.Map.Entry;

public class HashMapDemo {

    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("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.containsKey("cn"));
        
        //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());
        }
    }
}