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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