Map的常用遍历方式

创建一个Map对象，并存放相应的值

package com.zillion.action;

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

public class MyInterceptor {
    public static void main(String[] args) {
        Map<String, Integer> user = new HashMap<String, Integer>();
        user.put("张三", 30);
        user.put("李四", 40);
        user.put("王五", 50);
        user.put("赵六", 60);
}

1. 通过先遍历所有的key，通过key再获得值

Set<String> keySet = user.keySet();
        for (String key : keySet) {
            System.out.println(key+" "+user.get(key));
        }

2. 先获得entrySet对象，根据对象获得键和值

Set<Entry<String, Integer>> entrySet = user.entrySet();
        for (Entry<String, Integer> entry : entrySet) {
            System.out.println(entry.getKey()+" "+entry.getValue());
        }

3. 通过迭代器遍历

Iterator<Entry<String, Integer>> iterator = user.entrySet().iterator();
        while (iterator.hasNext()) {
            Entry<String, Integer> entry = iterator.next();
            System.out.println(entry.getKey()+" "+entry.getValue());
        }