JSONObject和JSONArray之间的区别

Question

在简要介绍一下Google后,我发现这个链接描述了差异,但从语法的角度来看.

在编程场景中何时优先于另一个？

Answer 1

当您在Android中使用JSON数据时,您将使用JSONArray解析以数组括号开头的JSON.JSON中的数组用于组织相关项的集合(可以是JSON对象).
例如:[{"name":"item 1"},{"name": "item2} ]

另一方面,您将JSONObject在处理以花括号开头的JSON时使用.JSON对象通常用于包含与一个项相关的键/值对.例如:{"name": "item1", "description":"a JSON object"}

当然,JSON数组和对象可以彼此嵌套.一个常见的例子是API,它返回一个JSON对象,其中包含一些元数据以及与您的查询匹配的项目数组:

{"startIndex": 0, "data": [{"name":"item 1"},{"name": "item2"} ]}

Answer 2

差异与(哈希)地图与列表相同.

的JSONObject:

• 包含命名值(键 - >值对,元组或任何您想要调用的值)
  • 喜欢 {ID : 1}
• 元素的顺序并不重要
  • 一个JSONObject {id: 1, name: 'B'}等于{name: 'B', id: 1}.

JSONArray:

• 仅包含系列值
  • 喜欢 [1, 'value']
• 价值秩序很重要
  • 数组[1,'value']是不一样的['value',1]

例

JSON Object --> { "":""}

JSON Array --> [ , , , ]

{"employees":[
    {"firstName":"John", "lastName":"Doe"},
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"Peter", "lastName":"Jones"}
]}

Answer 3

最好以编程方式理解.

当语法是{}这时JsonObject

当语法是[]这时JsonArray

A JSONObject是一个类似JSON的对象,可以表示为一个元素JSONArray.JSONArray可以包含一个(或许多)JSONObject

希望这对你有所帮助!

Answer 4

为了更简单地理解它，以下是 JSON 对象和 JSON 数组之间的差异：

链接到表格差异：https : //i.stack.imgur.com/GIqI9.png

JSON 数组

1. Arrays in JSON are used to organize a collection of related items
   (Which could be JSON objects)
2.  Array values must be of type string, number, object, array, boolean or null
3.  Syntax: 
           [ "Ford", "BMW", "Fiat" ]
4.  JSON arrays are surrounded by square brackets []. 
    **Tip to remember**  :  Here, order of element is important. That means you have 
    to go straight like the shape of the bracket i.e. straight lines. 
   (Note :It is just my logic to remember the shape of both.) 
5.  Order of elements is important. Example:  ["Ford","BMW","Fiat"] is not 
    equal to ["Fiat","BMW","Ford"]
6.  JSON can store nested Arrays that are passed as a value.

JSON 对象

1.  JSON objects are written in key/value pairs.
2.  Keys must be strings, and values must be a valid JSON data type (string, number, 
    object, array, boolean or null).Keys and values are separated by a colon.
    Each key/value pair is separated by a comma.
3.  Syntax:
         { "name":"Somya", "age":25, "car":null }
4.  JSON objects are surrounded by curly braces {} 
    Tip to remember : Here, order of element is not important. That means you can go 
    the way you like. Therefore the shape of the braces i.e. wavy. 
    (Note : It is just my logic to remember the shape of both.)
5.  Order of elements is not important. 
    Example:  { rollno: 1, firstname: 'Somya'} 
                   is equal to 
             { firstname: 'Somya', rollno: 1}
6.  JSON can store nested objects in JSON format in addition to nested arrays.

Answer 5

我总是使用对象,它更容易扩展,JSON数组不是.例如,您最初将某些数据作为json数组,然后您需要在其上添加一个状态标题,除非您将数据嵌套在对象中,否则它会有点卡住.唯一的缺点是创建/解析的复杂性略有增加.

而不是

[datum0, datum1, datumN]

你有

{data: [datum0, datum1, datumN]}

然后你可以添加更多......

{status: "foo", data: [datum0, datum1, datumN]}

Answer 6

两者的使用取决于数据的结构。

简而言之，如果您计划优先考虑主键等唯一标识符，则可以使用嵌套对象方法。

例如：

  {
     "Employees" : {
           "001" : {
               "Name" : "Alan",
               "Children" : ["Walker", "Dua", "Lipa"]
                },
           "002" : {
               "Name" : "Ezio",
               "Children" : ["Kenvey", "Connor", "Edward"]
                }
      }

或者，如果您打算存储一组不需要唯一标识的值，请使用数组优先方法。

例如：

     {
        "Employees":[
               {
                   "Name" : "Alan",
                   "Children" : ["Walker", "Dua", "Lipa"]
               },
               {
                   "Name" : "Ezio",
                   "Children" : ["Kenvey", "Connor", "Edward"]
               }
          ]
       }
   

尽管您可以使用带有标识符的第二种方法，但在某些情况下查询和理解可能会更困难或太复杂。此外，根据数据库，人们可能必须应用一种合适的方法。例如：MongoDB / Firebase