GSON将数据对象的数组到JSON - 机器人 [英] GSON turn an array of data objects into json - Android

问题描述

目前我正在与web视图前端的原生Android应用程序。

Currently I am working on a native android app with webView front end.

我是这样的：

public class dataObject
{
  int a;
  String b;
}

和在活动中，

我已经做数据对象的数组，表示数据对象X [5];

I have made an array of dataObject, say dataObject x[5];

现在我想在回调函数通过这5个数据对象，以我的JavaScript web视图界面JSON。

Now i want to pass these 5 dataObject to my javascript webView interface as JSON in a callback function.

我看了看，通过互联网，似乎最喜欢的教程来谈谈如何转换 fromJson（）。有没有很多关于的toJSON（）。我发现一个告诉我， dataObject.toJson（），是可行的。

I looked through the internet, seems like most tutorials talk about how to convert fromJson(). There are not a lot about toJson(). I found one that taught me that dataObject.toJson(), would work.

但我怎么能够通过全部5个数据对象？

But how can I pass all 5 dataObjects?

我是pretty的新本。谢谢

I am pretty new to this. Thanks

推荐答案

下面是关于如何使用GSON使用对象列表的COM prehensive例子。这应该表现出的完全的如何转换到/从Json的，如何引用列表等。

Here's a comprehensive example on how to use Gson with a list of objects. This should demonstrate exactly how to convert to/from Json, how to reference lists, etc.

Test.java

import com.google.gson.Gson;
import java.util.List;
import java.util.ArrayList;
import com.google.gson.reflect.TypeToken;
import java.lang.reflect.Type;


public class Test {

  public static void main (String[] args) {

    // Initialize a list of type DataObject
    List<DataObject> objList = new ArrayList<DataObject>();
    objList.add(new DataObject(0, "zero"));
    objList.add(new DataObject(1, "one"));
    objList.add(new DataObject(2, "two"));

    // Convert the object to a JSON string
    String json = new Gson().toJson(objList);
    System.out.println(json);

    // Now convert the JSON string back to your java object
    Type type = new TypeToken<List<DataObject>>(){}.getType();
    List<DataObject> inpList = new Gson().fromJson(json, type);
    for (int i=0;i<inpList.size();i++) {
      DataObject x = inpList.get(i);
      System.out.println(x);
    }

  }


  private static class DataObject {
    private int a;
    private String b;

    public DataObject(int a, String b) {
      this.a = a;
      this.b = b;
    }

    public String toString() {
      return "a = " +a+ ", b = " +b;
    }
  }

}

要编译：

javac -cp "gson-2.1.jar:." Test.java

和最终运行它：

java -cp "gson-2.1.jar:." Test

需要注意的是，如果你使用的是Windows，你必须切换：与; 在previous两个命令。的

Note that if you're using Windows, you'll have to switch : with ; in the previous two commands.

在你运行它，你应该看到下面的输出：

After you run it, you should see the following output:

[{"a":0,"b":"zero"},{"a":1,"b":"one"},{"a":2,"b":"two"}]
a = 0, b = zero
a = 1, b = one
a = 2, b = two

请记住，这仅仅是一个命令行程序的演示的它是如何工作的，但同样的原则也适用Android的环境（参考JAR库等）。在

Keep in mind that this is only a command line program to demonstrate how it works, but the same principles apply within the Android environment (referencing jar libs, etc.)

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