问题描述
我有我的Android应用程序与GSON一个问题。
I am having a problem with GSON in my Android app.
JSON输入
[
{"id":"1202","parent_id":"0","agrpcount":"0","disp_order":"1","code":"PROD-NEW","name":"New Products","active":"1"},
{"id":"1119","parent_id":"0","agrpcount":"0","disp_order":"2","code":"PROD-VID","name":"\\\"How To\\\" Videos","active":"1"},
{"id":"1685","parent_id":"0","agrpcount":"0","disp_order":"3","code":"SUPP-RESOUR","name":"Support Resources","active":"1"},
{"id":"49","parent_id":"0","agrpcount":"0","disp_order":"109","code":"EQ","name":"Equipment for Sign Making","active":"1"},
{"id":"22","parent_id":"0","agrpcount":"0","disp_order":"110","code":"application-tape","name":"Application Tapes","active":"1"}
]
对于每个数组项容器类
Container class for each array item
public class Category {
public int id;
public int parent_id;
public int agrpcount;
public int disp_order;
public String code;
public String name;
public int active;
}
类加载类阵列
public static List<Category> getCategories(){
Category[] cats;
Gson gson = new Gson();
cats = gson.fromJson(strJSON, Category[].class);
List<Category> CatsList = Arrays.asList(cats);
return CatsList;
}
当我运行这个code我得到在日志下面
When I run this code I get the following in the Log
02-28 15:15:42.471: ERROR/AndroidRuntime(777): Caused by: java.lang.RuntimeException: No-args constructor for class com.signwarehouse.catalog.SWService$Category does not exist. Register an InstanceCreator with Gson for this type to fix this problem.
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.MappedObjectConstructor.constructWithNoArgConstructor(MappedObjectConstructor.java:64)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.MappedObjectConstructor.construct(MappedObjectConstructor.java:53)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonObjectDeserializationVisitor.constructTarget(JsonObjectDeserializationVisitor.java:40)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonDeserializationVisitor.getTarget(JsonDeserializationVisitor.java:56)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:109)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonDeserializationVisitor.visitChild(JsonDeserializationVisitor.java:107)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonDeserializationVisitor.visitChildAsObject(JsonDeserializationVisitor.java:95)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonArrayDeserializationVisitor.visitArray(JsonArrayDeserializationVisitor.java:72)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:117)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonDeserializationContextDefault.fromJsonArray(JsonDeserializationContextDefault.java:64)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.JsonDeserializationContextDefault.deserialize(JsonDeserializationContextDefault.java:49)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.Gson.fromJson(Gson.java:568)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.Gson.fromJson(Gson.java:515)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.Gson.fromJson(Gson.java:484)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.Gson.fromJson(Gson.java:434)
02-28 15:15:42.471: ERROR/AndroidRuntime(777): at com.google.gson.Gson.fromJson(Gson.java:406)
我尝试添加一个无参数的构造函数的类类，但是这并没有帮助。自从Java毫无疑问会自动创建它。
I tried adding a no-args constructor to the Category class, but this didn't help. No surprise since Java creates it automatically.
有没有人有任何想法如何解决这一问题？
Does anyone have any idea how to fix this?
感谢。
推荐答案
试图使得Category类公共的静态类...
Trying making the Category class a public static class...
public static class Category {/* fields */}
我敢打赌，发生的事情是，因为你并没有使类的静态它试图创建父/外部类（com.signwarehouse.catalog.SWService）第一这可能不具有一个无参数的构造函数。
I bet what's happening is since you didn't make the class static it is trying to create your parent/outer class (com.signwarehouse.catalog.SWService) first which probably doesn't have a no-arg constructor.
这篇关于Android和GSON抛出无参数的构造函数未发现异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！