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  • Android 无法强制转换com.google.gson.internal.LinkedTreeMap

Android 无法强制转换com.google.gson.internal.LinkedTreeMap

android json

Android 无法强制转换com.google.gson.internal.LinkedTreeMap,android,json,gson,retrofit,Android,Json,Gson,Retrofit,我第一次使用GSON进行改装。它使用静态数据流畅地运行，但在动态数据的情况下显示上述错误。它在设置文本值时显示适配器错误 main活动 public class MainActivity extends AppCompatActivity { String Navigation_Url = "http://www.xxxxxxxx.com"; ListView listView; ArrayList<ListPojo> listPojos = new Ar

我第一次使用GSON进行改装。它使用静态数据流畅地运行，但在动态数据的情况下显示上述错误。它在设置文本值时显示适配器错误

main活动

public class MainActivity extends AppCompatActivity {


    String Navigation_Url = "http://www.xxxxxxxx.com";
    ListView listView;
    ArrayList<ListPojo> listPojos = new ArrayList<>();
    ListRetrofitAndroid listRetrofitAndroid;


    ArrayList countries = new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        listView = (ListView) findViewById(R.id.listView);
        getRetrofitData();
    }


    void getRetrofitData() {
        Retrofit retrofit = new Retrofit.Builder().baseUrl(Navigation_Url).addConverterFactory(GsonConverterFactory.create()).build();
        CountryArrayAPI api = retrofit.create(CountryArrayAPI.class);
        Call<List> call = api.getCountries();


        call.enqueue(new Callback<List>() {

            @Override
            public void onResponse(Call<List> call, Response<List> response) {
                Gson gson = new Gson();
                try {
                    listPojos = (ArrayList) response.body();
                    System.out.println("the ArrayList is" + listPojos);


//                    ArrayList<ListPojo> merchantOfferModels = gson.fromJson(response, new TypeToken<ListPojo>() {}.getType());









                    listRetrofitAndroid = new ListRetrofitAndroid(getApplicationContext(), listPojos);
                    listView.setAdapter(listRetrofitAndroid);


                } catch (Exception e) {
                    Log.d("onResponse", "There is an error");
                    e.printStackTrace();
                }

            }

            @Override
            public void onFailure(Call<List> call, Throwable t) {
                Log.d("Failure", t.toString());
            }
        });

    }

}
接口

public interface CountryArrayAPI {
    @GET("/api/popular_destinations")
    public Call<List> getCountries();
}

09-19 05:15:32.475 18949-18949/com.example.user_pc.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                   Process: com.example.user_pc.myapplication, PID: 18949
                                                                                   java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to com.example.user_pc.myapplication.pojo.ListPojo
                                                                                       at com.example.user_pc.myapplication.adpater.ListRetrofitAndroid.getView(ListRetrofitAndroid.java:71)
                                                                                       at android.widget.AbsListView.obtainView(AbsListView.java:2255)
                                                                                       at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
                                                                                       at android.widget.ListView.onMeasure(ListView.java:1175)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:934)
                                                                                       at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:973)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
                                                                                       at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
                                                                                       at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
                                                                                       at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
                                                                                       at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
                                                                                       at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
                                                                                       at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
                                                                                       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
                                                                                       at android.view.Choreographer.doCallbacks(Choreographer.java:574)
                                                                                       at android.view.Choreographer.doFrame(Choreographer.java:544)
                                                                                       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
                                                                                       at android.os.Handler.handleCallback(Handler.java:733)
                                                                                       at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                       at android.os.Looper.loop(Looper.java:136)
                                                                                       at android.app.ActivityThread.main(ActivityThread.java:5001)
                                                                                       at java.lang.reflect.Method.invokeNative(Native Method)
                                                                                       at java.lang.reflect.Method.invoke(Method.java:515)
                                                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
                                                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
                                                                                       at dalvik.system.NativeStart.main(Native Method)
StsckTrace

public interface CountryArrayAPI {
    @GET("/api/popular_destinations")
    public Call<List> getCountries();
}

09-19 05:15:32.475 18949-18949/com.example.user_pc.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                   Process: com.example.user_pc.myapplication, PID: 18949
                                                                                   java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to com.example.user_pc.myapplication.pojo.ListPojo
                                                                                       at com.example.user_pc.myapplication.adpater.ListRetrofitAndroid.getView(ListRetrofitAndroid.java:71)
                                                                                       at android.widget.AbsListView.obtainView(AbsListView.java:2255)
                                                                                       at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
                                                                                       at android.widget.ListView.onMeasure(ListView.java:1175)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:934)
                                                                                       at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:973)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
                                                                                       at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
                                                                                       at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
                                                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
                                                                                       at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
                                                                                       at android.view.View.measure(View.java:16497)
                                                                                       at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
                                                                                       at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
                                                                                       at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
                                                                                       at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
                                                                                       at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
                                                                                       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
                                                                                       at android.view.Choreographer.doCallbacks(Choreographer.java:574)
                                                                                       at android.view.Choreographer.doFrame(Choreographer.java:544)
                                                                                       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
                                                                                       at android.os.Handler.handleCallback(Handler.java:733)
                                                                                       at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                       at android.os.Looper.loop(Looper.java:136)
                                                                                       at android.app.ActivityThread.main(ActivityThread.java:5001)
                                                                                       at java.lang.reflect.Method.invokeNative(Native Method)
                                                                                       at java.lang.reflect.Method.invoke(Method.java:515)
                                                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
                                                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
                                                                                       at dalvik.system.NativeStart.main(Native Method)
如何解决这个问题？

我目前完全不知道如何使用
List
处理json。但您可以像这样使用数组：

public interface CountryArrayAPI {
    @GET("/api/popular_destinations")
    public Call<ListPojo[]> getCountries();
}

公共接口CountryArrayAPI{
@获取（“/api/popular\u destinations”）
公共呼叫getCountries（）；
}
您使用的是
ArrayList
，因此需要确保解析应该使用正确的类型
List
，而不是没有类型的
List

由于缺少类型信息，
gson
正在返回 创建的对象
LinkedTreeMap
，由于您使用的是
raw
类型（对于未选中的强制转换应该是一个警告），声明为具体类型，这将在适配器实际需要
PojoObject
时产生问题，但在内部是另一回事。所以解决方案

我也是

public interface CountryArrayAPI {
    @GET("api/popular_destinations")
    public Call<List<ListPojo>> getCountries();
}
并始终编码到
接口
so

List<ListPojo> listPojos = ...;

List listPojos=。。。；
当然，纳宾，我会检查这个谢谢你，伙计，这很有效。你能详细说明我的问题吗？这将是一个很大的帮助。在我修改我的答案时，简而言之，你使用的是
列表
，它没有类型参数，因此不会进行解析，你会得到不需要的类型对象列表，因此，永远不要使用原始类型
列表
我很高兴我能帮助pal，happy coding我有一个指南，在我看来，在使用接口的情况下。我不能在通常得到响应的相同方法上添加url。是的，你可以，你可以使用占位符
{}
或完整的url，看到了吗 
call.enqueue(new Callback<List<ListPojo>>() {

            @Override
            public void onResponse(Call<List<ListPojo>> call, Response<List<ListPojo>> response) {
            listPojos = response.body();

List<ListPojo> listPojos = ...;