Java Map 的三种遍历方式

第一种是遍历 map中键所对应的值

public static void work(Map<String, Student> map) {

Collection<Student> c = map.values();

Iterator it = c.iterator();

for (; it.hasNext();) {

System.out.println(it.next());

}

}

第二种是遍历 map中的 键 和 值

public static void workByKeySet(Map<String, Student> map) {

Set<String> key = map.keySet();

for (Iterator it = key.iterator(); it.hasNext();) {

String s = (String) it.next();

System.out.println(map.get(s));

}

}

第三种和第二种差不多，但是比较灵活

public static void workByEntry(Map<String, Student> map) {

Set<Map.Entry<String, Student>> set = map.entrySet();

for (Iterator<Map.Entry<String, Student>> it = set.iterator(); it.hasNext();) {

Map.Entry<String, Student> entry = (Map.Entry<String, Student>) it.next();

System.out.println(entry.getKey() + "--->" + entry.getValue());

}

}

}