java之map遍历

java开发中常常会用到遍历，所以下边就列举四种map的遍历方法。

public class testMap {

    public static void main(String[] args) {
        Map<Object, Object> map = new HashMap<Object, Object>();
        map.put("01", "A");
        map.put("02", "B");
        map.put("03", "C");
//        test1(map);
//        test2(map);
//        test3_1(map);
//        test3_2(map);
        test4(map);
    }

    /**
     * 遍历map方法一
     *
     * @param map
     */
    public static void test1(Map<Object, Object> map) {
        for (Entry<Object, Object> entry : map.entrySet()) {
            System.out.println("Key = " + entry.getKey() + ", Value = "
                    + entry.getValue());
        }
    }

    /**
     * 遍历map方法二
     *
     * @param map
     */
    public static void test2(Map<Object, Object> map) {
        // 遍历map中的键
        for (Object key : map.keySet()) {
            System.out.println("Key = " + key);
        }

        // 遍历map中的值
        for (Object value : map.values()) {
            System.out.println("Value = " + value);
        }
    }

    /**
     * 遍历map方法三（非泛型）
     *
     * @param map
     */
    public static void test3_1(Map<Object, Object> map) {
        Iterator<Entry<Object, Object>> entries = map.entrySet().iterator();
        Entry<Object, Object> entry;
        while (entries.hasNext()) {
            entry = entries.next();
            System.out.println("Key = " + entry.getKey() + ", Value = "
                    + entry.getValue());
        }
    }

    /**
     * 遍历map方法三（泛型）
     *
     * @param map
     */
    public static void test3_2(Map<Object, Object> map) {
        Iterator entries = map.entrySet().iterator();
        Entry entry;
        while (entries.hasNext()) {
            entry = (Entry) entries.next();
            System.out.println("Key = " + entry.getKey() + ", Value = "
                    + entry.getValue());
        }
    }

    /**
     * 遍历map方法四
     *
     * @param map
     */
    public static void test4(Map<Object, Object> map) {
        for (Object key : map.keySet()) {
            System.out.println("Key = " + key + ", Value = " + map.get(key));
        }
    }
}