关于Map集合的遍历总结

转：http://www.cnblogs.com/lsgspace/p/4666020.html

以下是遍历Map集合的几种方式：

public static void main(String[] args)
{
    Map<String, String> map = new HashMap<String, String>();
    map.put("1", "张三");
    map.put("2", "李四");
    map.put("3", "王五");

    //调用
}

1、通过Map.keySet遍历key和value

private static void findKey(Map<String, String> map)
{
    System.out.println("findKey");

    for (String key : map.keySet())
    {
        System.out.println("key = " + key);
        System.out.println("value = " + map.get(key));
    }
}

2、通过Map.values遍历value

private static void findValue(Map<String, String> map)
{
    System.out.println("findValue");

    for (String value : map.values())
    {
        System.out.println("value = " + value);
    }
}

3、通过Map.entrySet和迭代器遍历Map

private static void findIterator(Map<String, String> map)
{
    System.out.println("findIterator");

    Iterator<Map.Entry<String, String>> carIterator = map.entrySet().iterator();

    while (carIterator.hasNext())
    {
        Map.Entry<String, String> entry = carIterator.next();
        System.out.println("key = " + entry.getKey());
        System.out.println("value = " + entry.getValue());
    }
}

4、Map.entrySet加for in 循环（推荐）

private static void findEntrySet(Map<String, String> map)
{
    System.out.println("findEntrySet");

    for (Entry<String, String> entry : map.entrySet())
    {
        System.out.println("key = " + entry.getKey());
        System.out.println("value = " + entry.getValue());
    }
}