java List里面放的是一个个map 如何遍历 获取全部map的key,value, 效率最优
只能两层遍历
for (Map map: listMap) {
for (Map.Entry<String, Object> entry : map.entrySet()) {
String key = entry.getKey();
Object value = entry.getValue();
// ...
}
}
for (Map map : listMap) {
}
直接遍历就可以呀,你还想怎么遍历?
JDK版本多少?1.8之后Lambda 表达式效率应该比2楼那个高一点,如果不是1.6的话2楼那种写法就好了
List<Map<String, String>> mapList = new ArrayList<Map<String, String>>();
Map<String, String> map = new HashMap<String, String>();
map.put("111", "111");
map.put("11", "11");
Map<String, String> map1 = new HashMap<String, String>();
map1.put("222", "222");
map1.put("22", "22");
mapList.addAll(Arrays.asList(map, map1));
mapList.forEach(stringMap -> {
stringMap.forEach((k, v) -> {
System.out.println(k + "," + v);
});
});
其实就是比较遍历MAP,题主可以参考一下的链接,https://github.com/giantray/stackoverflow-java-top-qa/blob/master/contents/iterate-through-a-hashmap.md