Java中Map的遍历

话不多说直接上代码

public class M {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<String, String>();
        map.put("key1", "value1");
        map.put("key2", "value2");
        map.put("key3", "value3");
//通过通过遍历entrySet()方法得到的Set
        for (Map.Entry<String, String> m : map.entrySet()) {
            System.out.println("KEY:" + m.getKey() + "VALUE:" + m.getValue());
        }

//通过迭代器Iterator遍历
        Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, String> entry = iterator.next();
            System.out.println("KEY:" + entry.getKey() + "VALUE:" + entry.getValue());
        }
//遍历keySet()方法获得的Set(通过键找值遍历，这种方式的效率比较低，因为本身从键取值是耗时的操作；)
        for (String key : map.keySet()) {
            System.out.println("KEY:" + key + "VALUE:" + map.get(key));
        }
//使用keySet()和values()，这种方法用于单独只获取key或者value很好
        for (String key:map.keySet()){
            System.out.println("KEY:" + key);
        }
        for (String value:map.values()){
            System.out.println("VALUE:" + value);
        }
    }
}