java如何获取json数组 java获取jsonarray长度

前言：数组没有length()这个方法，有length的属性。String有有length()这个方法。

 

1.String字符串

String str = "abcdefg";
str.length();

 

2.Array数组

int[] arr = new int[10];
System.out.println(arr.length);

 

3.List集合

List list = new ArrayList();
list.size();

 

4.JSONArray

String jsonMessage = 
                  "[{'num':'成绩','外语':88,'历史':65,'地理':99,'object':{'aaa':1111,'bbb':2222,'ccc':'3333'}},"
                + "{'num':'兴趣','外语':28,'历史':45,'地理':19,'object':{'aaa':1a11,'bbb':2a22,'ccc':'3a33'}},"
                + "{'num':'兴趣','外语':48,'历史':62,'地理':39,'object':{'aaa':1aaa,'bbb':2bb2,'ccc':'3c33'}}]";
        JSONArray myJsonArray = JSONArray.fromObject(jsonMessage);
            for (int i = 0; i < myJsonArray.size(); i++) 
            {
                //遍历
            }