Java 将 JSONArray 转换为 List<Object>？
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Converting JSONArray to List<Object>?
提问by FernandoPaiva
I'm trying deserializes a JSONArray to List. To do it I'm trying use Gson but I can't understand why doesn't works and all values of JSON are null.
我正在尝试将 JSONArray 反序列化为 List。为此，我正在尝试使用 Gson，但我不明白为什么不起作用并且 JSON 的所有值都为空。
How could I do this ?
我怎么能这样做？
JSON
JSON
{ "result" : [
{ "Noticia" : {
"created" : "2015-08-20 19:58:49",
"descricao" : "tttttt",
"id" : "19",
"image" : null,
"titulo" : "ddddd",
"usuario" : "FERNANDO PAIVA"
} },
{ "Noticia" : {
"created" : "2015-08-20 19:59:57",
"descricao" : "hhhhhhhh",
"id" : "20",
"image" : "logo.png",
"titulo" : "TITULO DA NOTICIA",
"usuario" : "FERNANDO PAIVA"
} }
] }
Deserializes
反序列化
List<Noticia> lista = new ArrayList<Noticia>();
Gson gson = new Gson();
JSONArray array = obj.getJSONArray("result");
Type listType = new TypeToken<List<Noticia>>() {}.getType();
lista = gson.fromJson(array.toString(), listType);
//testing - size = 2 but value Titulo is null
Log.i("LISTSIZE->", lista.size() +"");
for(Noticia n:lista){
Log.i("TITULO", n.getTitulo());
}
Class Noticia
班级通知
public class Noticia implements Serializable {
private static final long serialVersionUID = 1L;
private Integer id;
private String titulo;
private String descricao;
private String usuario;
private Date created;
private String image;
回答by ziviland
You parse json, that looks like
你解析json，看起来像
{ "result" : [
{
"created" : "2015-08-20 19:58:49",
"descricao" : "tttttt",
"id" : "19",
"image" : null,
"titulo" : "ddddd",
"usuario" : "FERNANDO PAIVA"
},
{
"created" : "2015-08-20 19:59:57",
"descricao" : "hhhhhhhh",
"id" : "20",
"image" : "logo.png",
"titulo" : "TITULO DA NOTICIA",
"usuario" : "FERNANDO PAIVA"
}
] }
You need to make another object Item and parse a list of them.
您需要创建另一个对象 Item 并解析它们的列表。
public class Item{
Noticia noticia;
}
Or you can interate through JSONArray, get field "noticia" from each then parse Noticia object from given JSONObject.
或者您可以通过 JSONArray 进行交互，从每个字段获取“noticia”字段，然后从给定的 JSONObject 解析 Noticia 对象。
回答by Atul
I think the problem could be something to do with toString() on JSONArray. But are you using obj.getAsJsonArray method?
我认为问题可能与 JSONArray 上的 toString() 有关。但是你使用 obj.get作为JsonArray 方法吗？
Try this:
尝试这个：
JSONArray arr = obj.getAsJsonArray("result");
Type listType = new TypeToken<List<Noticia>>() {
}.getType();
return new Gson().fromJson(arr , listType);
回答by cн?dk
There are two problems with your code :
您的代码有两个问题：
- First is that you are using a
getJsonArray()to get the array, which isn't part of Gsonlibrary, you need to use getAsJsonArray()method instead. - Second is that you are using
array.toString()which isn't obvious because for thefromJsonmethod you need ajsonArrayas parameter and notStringand that will cause you parse problems, just remove it.
- 首先是你使用 a
getJsonArray()来获取数组，它不是Gson库的一部分，你需要使用 getAsJsonArray()方法来代替。 - 其次是您正在使用
array.toString()哪个并不明显，因为对于该fromJson方法，您需要一个jsonArrayas 参数而不是String这会导致您解析问题，只需将其删除即可。
And use the following code to convert your jsonArrayto List<Noticia>:
并使用以下代码将您的转换jsonArray为List<Noticia>：
Type type = new TypeToken<List<Noticia>>() {}.getType();
List<Noticia> lista = gson.fromJson(array, type);
And your whole code will be:
你的整个代码将是：
Gson gson = new Gson();
JSONArray array = obj.getAsJsonArray("result");
Type type = new TypeToken<List<Noticia>>() {}.getType();
List<Noticia> lista = gson.fromJson(array, type);
//testing - size = 2 but value Titulo is null
Log.i("LISTSIZE->", lista.size() +"");
for(Noticia n:lista){
Log.i("TITULO", n.getTitulo());
}
回答by Saurabh
Noticia.java
通知.java
public class Noticia {
private String created;
private String descricao;
private String id;
private String image;
private String titulo;
private String usuario;
public String getCreated() {
return created;
}
public void setCreated(String created) {
this.created = created;
}
public String getDescricao() {
return descricao;
}
public void setDescricao(String descricao) {
this.descricao = descricao;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public String getTitulo() {
return titulo;
}
public void setTitulo(String titulo) {
this.titulo = titulo;
}
public String getUsuario() {
return usuario;
}
public void setUsuario(String usuario) {
this.usuario = usuario;
}
@Override
public String toString() {
return "Noticia [created=" + created + ", descricao=" + descricao
+ ", id=" + id + ", image=" + image + ", titulo=" + titulo
+ ", usuario=" + usuario + "]";
}
}
Result.java
结果.java
public class Result {
private Noticia Noticia;
public Noticia getNoticia() {
return Noticia;
}
public void setNoticia(Noticia noticia) {
Noticia = noticia;
}
@Override
public String toString() {
return "Result [Noticia=" + Noticia + "]";
}
}
Item.java
项目.java
import java.util.List;
public class Item {
private List<Result> result;
public List<Result> getResult() {
return result;
}
public void setResult(List<Result> result) {
this.result = result;
}
@Override
public String toString() {
return "Item [result=" + result + "]";
}
}
Main.java
主程序
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.testgson.beans.Item;
public class Main {
private static Gson gson;
static {
gson = new GsonBuilder().create();
}
public static void main(String[] args) {
String j = "{\"result\":[{\"Noticia\":{\"created\":\"2015-08-20 19:58:49\",\"descricao\":\"tttttt\",\"id\":\"19\",\"image\":null,\"titulo\":\"ddddd\",\"usuario\":\"FERNANDO PAIVA\"}},{\"Noticia\":{\"created\":\"2015-08-20 19:59:57\",\"descricao\":\"hhhhhhhh\",\"id\":\"20\",\"image\":\"logo.png\",\"titulo\":\"TITULO DA NOTICIA\",\"usuario\":\"FERNANDO PAIVA\"}}]}";
Item r = gson.fromJson(j, Item.class);
System.out.println(r);
}
}
Final result
最后结果
Item [result=[Result [Noticia=Noticia [created=2015-08-20 19:58:49, descricao=tttttt, id=19, image=null, titulo=ddddd, usuario=FERNANDO PAIVA]], Result [Noticia=Noticia [created=2015-08-20 19:59:57, descricao=hhhhhhhh, id=20, image=logo.png, titulo=TITULO DA NOTICIA, usuario=FERNANDO PAIVA]]]]
