遍历Map四种

遍历Map四种

public static void main(String[] args) {

Map<String, String> map = new HashMap<String, String>();
map.put("1", "value1");
map.put("2", "value2");
map.put("3", "value3");

//第种：普遍使用二取值
System.out.println("通Map.keySet遍历keyvalue：");
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
 
//第二种
System.out.println("通Map.entrySet使用iterator遍历key value：");
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}

//第三种：推荐尤其容量
System.out.println("通Map.entrySet遍历keyvalue");
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}

//第四种
System.out.println("通Map.values()遍历所value能遍历key");
for (String v : map.values()) {
System.out.println("value= " + v);
}
}