Java 如何将 JSONArray 转换为 int 数组？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/20068852/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to cast JSONArray to int array?
提问by volly
I'm having problems with the method JSONObject sayJSONHello().
我的方法有问题JSONObject sayJSONHello()。
@Path("/hello")
public class SimplyHello {
@GET
@Produces(MediaType.APPLICATION_JSON)
public JSONObject sayJSONHello() {
JSONArray numbers = new JSONArray();
numbers.put(1);
numbers.put(2);
numbers.put(3);
numbers.put(4);
JSONObject result = new JSONObject();
try {
result.put("numbers", numbers);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return result;
}
}
In the client side, I want to get an intarray, [1, 2, 3, 4], instead of the JSON
在客户端，我想得到一个int数组[1, 2, 3, 4]，而不是 JSON
{"numbers":[1,2,3,4]}
How can I do that?
我怎样才能做到这一点？
Client code:
客户端代码：
System.out.println(service.path("rest").path("hello")
.accept(MediaType.APPLICATION_JSON).get(String.class));
My method returns a JSONObject, but I want to extract the numbers from it, in order to perform calculations with these (e.g as an int[]).
我的方法返回 a JSONObject，但我想从中提取数字，以便使用这些（例如作为int[]）执行计算。
I reveive function as a JSONObject.
我将函数作为 JSONObject。
String y = service.path("rest").path("hello").accept(MediaType.APPLICATION_JSON).get(String.class);
JSONObject jobj = new JSONObject(y);
int [] id = new int[50];
id = (int [] ) jobj.optJSONObject("numbers:");
And then i get error: Cannot cast from JSONObject to int[]
然后我收到错误：无法从 JSONObject 转换为 int[]
2 other way
2 其他方式
String y = service.path("rest").path("hello").accept(MediaType.APPLICATION_JSON).get(String.class);
JSONArray obj = new JSONArray(y);
int [] id = new int[50];
id = (int [] ) obj.optJSONArray(0);
And this time i get: Cannot cast from JSONArray to int[]...
这一次我得到：无法从 JSONArray 转换为 int[]...
It doesn't work anyway..
反正也行不通。。
采纳答案by afsantos
I've never used this, nor have I tested it, but looking at your code and the documentation for JSONObjectand JSONArray, this is what I suggest.
我从来没有用过这个，我也没有测试过，但看着你的代码和文档JSONObject，并JSONArray，这是我的建议。
// Receive JSON from server and parse it.
String jsonString = service.path("rest").path("hello")
.accept(MediaType.APPLICATION_JSON).get(String.class);
JSONObject obj = new JSONObject(jsonString);
// Retrieve number array from JSON object.
JSONArray array = obj.optJSONArray("numbers");
// Deal with the case of a non-array value.
if (array == null) { /*...*/ }
// Create an int array to accomodate the numbers.
int[] numbers = new int[array.length()];
// Extract numbers from JSON array.
for (int i = 0; i < array.length(); ++i) {
numbers[i] = array.optInt(i);
}
This should work for your case. On a more serious application, you may want to check if the values are indeed integers, as optIntreturns 0when the value does not exist, or isn't an integer.
这应该适用于您的情况。在更严重的应用程序，你可能要检查如果值确实是整数，作为optInt回报0，当值不存在，或者不是一个整数。
Get the optional int value associated with an index. Zero is returned if there is no value for the index, or if the value is not a number and cannot be converted to a number.
获取与索引关联的可选 int 值。如果索引没有值，或者值不是数字且无法转换为数字，则返回零。
回答by TR1
Instead of -
代替 -
result.put("numbers", numbers);
you can try (I haven't tested this though)
你可以试试（不过我还没有测试过）
result.put(numbers);
Or iterate through the array "numbers" and put each one individually into the "result".
或者遍历数组“数字”并将每个单独放入“结果”中。
回答by jumps4fun
If you can accept a List as a result, and also can accept using Gson, there is a pretty easy way of doing this, in just a few lines of code:
如果您可以接受 List 作为结果，也可以接受使用 Gson，则有一种非常简单的方法可以做到这一点，只需几行代码：
Type listType = new TypeToken<LinkedList<Integer>>() {}.getType();
List<Integer> numbers = new Gson().fromJson(jobj.get("numbers"), listType);
I realize this is not exactly what you are asking for, but in my experience, a list of integers can be used in many of the same ways as a basic int[]. Further info on how to convert a linkedlist to an array, can be found here: How to convert linkedlist to array using `toArray()`?
我意识到这并不完全是您所要求的，但根据我的经验，整数列表可以以与基本 int[] 相同的许多方式使用。有关如何将链表转换为数组的更多信息，可以在此处找到：如何使用 `toArray()` 将链表转换为数组？
回答by Aniket Patil
You can also do this
你也可以这样做
JSONArray numberArr=jsonObject.getJSONArray("numbers");
int[] arr=new int[numberArr.length()];
for(int k=0;k<numberArr.length();k++)
arr[k]=numberArr.getInt(k);
回答by ucMedia
Here is a simple methodthat handles JSONArrayconverting to Int Array:
这是一个处理转换为的简单方法：JSONArrayInt Array
public static int[] JSonArray2IntArray(JSONArray jsonArray){
int[] intArray = new int[jsonArray.length()];
for (int i = 0; i < intArray.length; ++i) {
intArray[i] = jsonArray.optInt(i);
}
return intArray;
}
