遍历map
1.这是最常见的并且在大多数情况下也是最可取的遍历方式。在键值都需要时使用。
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
2.在for-each循环中遍历keys或values。
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
//遍历map中的键
for (Integer key : map.keySet()) {
System.out.println("Key = " + key);
}
//遍历map中的值
for (Integer value : map.values()) {
System.out.println("Value = " + value);
}
3.用迭代器迭代
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator();
while (entries.hasNext()) {
Map.Entry<Integ 大专栏 遍历map和lister, Integer> entry = entries.next();
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
4.通过键找值遍历（效率低）
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (Integer key : map.keySet()) {
Integer value = map.get(key);
System.out.println("Key = " + key + ", Value = " + value);
遍历list
1.超级for循环遍历
for(String attribute : list) {
System.out.println(attribute);
}
2.对于ArrayList来说速度比较快, 用for循环, 以size为条件遍历
for(int i = 0 ; i < list.size() ; i++) {
system.out.println(list.get(i));
}
3.用迭代器迭代
Iterator it = list.iterator();
while(it.hasNext()) {
System.ou.println(it.next);
}
原文：https://www.cnblogs.com/lijianming180/p/12433510.html