java 遍历map 方法[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。

遍历方法一( entrySet() 遍历)：

Iterator it = tempMap.entrySet().iterator();
  while (it.hasNext()) {
   Map.Entry entry = (Map.Entry) it.next();
   Object key = entry.getKey();
   Object value = entry.getValue();
   System.out.println("key=" + key + " value=" + value);
  }

遍历方法二( entrySet() 遍历)：

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

遍历方法三( keySet() 遍历)：

for (Iterator i = tempMap.keySet().iterator(); i.hasNext();) {
   Object obj = i.next();
   System.out.println(obj);// 循环输出key
   System.out.println("key=" + obj + " value=" + tempMap.get(obj));
  }
  for (Iterator i = tempMap.values().iterator(); i.hasNext();) {
   Object obj = i.next();
   System.out.println(obj);// 循环输出value
  }

遍历方法四( keySet() 遍历)：

for (Object o : tempMap.keySet()) {
   System.out.println("key=" + o + " value=" + tempMap.get(o));
  }

遍历方法五（遍历Map <String, ArrayList> map = new HashMap<String, ArrayList>();）：

Map<String, ArrayList> map = new HashMap<String, ArrayList>();
  Set<String> keys = map.keySet();
  Iterator<String> iterator = keys.iterator();
  while (iterator.hasNext()) {
   String key = iterator.next();
   ArrayList arrayList = map.get(key);
   for (Object o : arrayList) {
    System.out.println(o + "遍历过程");
   }
  }

or

 Map<String, List> mapList = new HashMap<String, List>();
  for (Map.Entry entry : mapList.entrySet()) {
   String key = entry.getKey().toString();
   List<String> values = (List) entry.getValue();
   for (String value : values) {
    System.out.println(key + " --> " + value);
   }
  }