这是我的SelectedCategoryActivity.java代码 显示错误，ArrayList无法转换为com.panaceasoft.citiesdirectory.models.PCityData，而我在其他代码中使用相同的方式
package com.panaceasoft.citiesdirectory.activities;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.design.widget.CollapsingToolbarLayout;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.support.v7.widget.Toolbar;
import android.text.TextPaint;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.DefaultRetryPolicy;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.panaceasoft.citiesdirectory.Config;
import com.panaceasoft.citiesdirectory.GlobalData;
import com.panaceasoft.citiesdirectory.R;
import com.panaceasoft.citiesdirectory.adapters.CategoryAdapter;
//import com.panaceasoft.citiesdirectory.adapters.CategoryAdapter1;
//import com.panaceasoft.citiesdirectory.models.CategoryRowData;
import com.panaceasoft.citiesdirectory.adapters.CityAdapter;
import com.panaceasoft.citiesdirectory.listeners.ClickListener;
import com.panaceasoft.citiesdirectory.listeners.RecyclerTouchListener;
import com.panaceasoft.citiesdirectory.models.CategoryData;
import com.panaceasoft.citiesdirectory.models.CityRowData;
import com.panaceasoft.citiesdirectory.models.PCityData;
import com.panaceasoft.citiesdirectory.models.PItemData;
import com.panaceasoft.citiesdirectory.models.PSubCategoryData;
import com.panaceasoft.citiesdirectory.utilities.Utils;
import com.squareup.picasso.Picasso;
import org.json.JSONException;
import org.json.JSONObject;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
/**
* Created by dell on 04-Jul-16.
*/
public class SelectedCategoryActivity extends AppCompatActivity {
private ProgressDialog prgDialog;
private String jsonStatusSuccessString;
private CollapsingToolbarLayout collapsingToolbar;
private Toolbar toolbar;
private ImageView detailImage;
private TextView txtTitle;
private RecyclerView mRecyclerView;
private StaggeredGridLayoutManager mLayoutManager;
private CityAdapter mAdapter;
private List<PCityData> myDataset = new ArrayList<>();
private CityRowData info;
private int selectedCategoryID;
private int selectedCityID;
private CategoryData category;
private PCityData city;
private ArrayList<PCityData> cityArrayList ;
//private ArrayList<PCityData> cityArrayData ;
private ArrayList<PSubCategoryData> subCategoryArrayList ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_selected_category);
initUI();
initData();
saveSelectedCategoryInfo(category);
bindData();
loadCityGrid();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_news, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_news) {
Utils.psLog("Open News Activity");
final Intent intent;
intent = new Intent(this, NewsListActivity.class);
intent.putExtra("selected_category_id", selectedCategoryID + "");
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
finish();
overridePendingTransition(R.anim.blank_anim, R.anim.left_to_right);
}
private void initUI() {
initToolbar();
initCollapsingToolbarLayout();
}
private void initCollapsingToolbarLayout(){
try {
collapsingToolbar = (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
} catch (Exception e) {
Utils.psErrorLogE("Error in initCollapsingToolbarLayout.", e);
}
}
private void initToolbar() {
try {
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
if(Utils.isAndroid_5_0()){
Utils.setMargins(toolbar, 0, -102, 0, 0);
}
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
toolbar.setTitle("");
toolbar.startAnimation(AnimationUtils.loadAnimation(this, R.anim.fade_in));
} catch (Resources.NotFoundException e) {
Utils.psErrorLogE("Error in initToolbar.", e);
}
}
private void initData() {
try {
jsonStatusSuccessString = getResources().getString(R.string.json_status_success);
requestData(Config.APP_API_URL + Config.GET_ALL);
detailImage = (ImageView) findViewById(R.id.detail_image);
category = GlobalData.categorydata;
//city = GlobalData.citydata;
selectedCategoryID = category.id;
//selectedCityID = city.id;
} catch (Exception e) {
Utils.psErrorLogE("Error in initData.", e);
}
}
private void bindData() {
try {
if(collapsingToolbar != null){
collapsingToolbar.setTitle(Utils.getSpannableString(category.name));
makeCollapsingToolbarLayoutLooksGood(collapsingToolbar);
}
Picasso.with(getApplicationContext()).load(Config.APP_IMAGES_URL + category.cover_image_file).into(detailImage);
} catch (Exception e) {
Utils.psErrorLogE("Error in bindData.", e);
}
}
private void requestData(String uri) {
JsonObjectRequest request = new JsonObjectRequest(uri,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
String status = response.getString("status");
Utils.psLog("City Status >>>>>>>>>>>>>: " + status);
if (status.equals(jsonStatusSuccessString)) {
Gson gson = new Gson();
Type listType = new TypeToken<List<PCityData>>() {
}.getType();
GlobalData.citydata = (PCityData) gson.fromJson(response.getString("data"), listType);
//cityArrayList = gson.fromJson(response.getString("data"), listType);
Utils.psLog("City Count >>>>>>>>>>>>>: " + cityArrayList.size());
updateGlobalCityList();
}
} catch (JSONException e) {
Utils.psErrorLogE("Error in loading City List.", e);
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
public void onErrorResponse(VolleyError error) {
prgDialog.cancel();
Utils.psLog("Error: " + error.getMessage());
}
// @Override
});
RequestQueue queue = Volley.newRequestQueue(this.getApplicationContext());
queue.add(request);
}
private void updateGlobalCityList() {
GlobalData.cityDatas.clear();
for (PCityData cd : cityArrayList) {
GlobalData.cityDatas.add(cd);
}
}
public void loadCityGrid() {
try {
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new CityAdapter(myDataset, mRecyclerView);
mRecyclerView.setAdapter(mAdapter);
//cityArrayList = category.cities;
// for (PCityData cd : cityArrayList) {
// subCategoryArrayList = cd.sub_categories;
// info = new CityRowData();
//info.setCityId(cd.id);
// info.setCityName(cd.name);
//info.setCityImage(cd.cover_image_file);
// myDataset.add(info);
// }
mAdapter.notifyItemInserted(myDataset.size());
mRecyclerView.addOnItemTouchListener(new RecyclerTouchListener(this, mRecyclerView, new ClickListener() {
@Override
public void onClick(View view, int position) {
onItemClicked(position);
}
@Override
public void onLongClick(View view, int position) {
}
}));
mRecyclerView.startAnimation(AnimationUtils.loadAnimation(this, R.anim.fade_in));
} catch (Resources.NotFoundException e) {
Utils.psErrorLogE("Error in loadCityGrid.", e);
}
}
public void onItemClicked( int position){
final Intent intent;
intent = new Intent(this,SubCategoryActivity.class);
GlobalData.citydata = cityArrayList.get(position);
intent.putExtra("selected_city_index", position );
intent.putExtra("selected_category_id", selectedCategoryID);
intent.putExtra("selected_city_id", cityArrayList.get(0).id);
startActivity(intent);
overridePendingTransition(R.anim.right_to_left, R.anim.blank_anim);
}
private void makeCollapsingToolbarLayoutLooksGood(CollapsingToolbarLayout collapsingToolbarLayout) {
try {
final Field field = collapsingToolbarLayout.getClass().getDeclaredField("mCollapsingTextHelper");
field.setAccessible(true);
final Object object = field.get(collapsingToolbarLayout);
final Field tpf = object.getClass().getDeclaredField("mTextPaint");
tpf.setAccessible(true);
((TextPaint) tpf.get(object)).setTypeface(Utils.getTypeFace(Utils.Fonts.ROBOTO));
((TextPaint) tpf.get(object)).setColor(getResources().getColor(R.color.colorAccent));
} catch (Exception ignored) {
}
}
private void saveSelectedCategoryInfo(CategoryData ct) {
try {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = prefs.edit();
editor.putInt("_id", ct.id);
editor.putString("_name", ct.name);
editor.putString("_cover_image", ct.cover_image_file);
// editor.putString("_address", ct.address);
// editor.putString("_city_region_lat", ct.lat);
// editor.putString("_city_region_lng", ct.lng);
editor.commit();
} catch (Exception e) {
Utils.psErrorLogE("Error in saveSelectedCategoryInfo.", e);
}
}
}
GlobalData.java
package com.panaceasoft.citiesdirectory;
import com.panaceasoft.citiesdirectory.models.CategoryData;
import com.panaceasoft.citiesdirectory.models.PCityData;
import com.panaceasoft.citiesdirectory.models.PItemData;
import java.util.ArrayList;
public class GlobalData {
public static PItemData itemData = null;
public static PCityData citydata = null;
public static CategoryData categorydata = null;
public static ArrayList<PCityData> cityDatas = new ArrayList<PCityData>();
public static ArrayList<CategoryData> categoryDatas = new ArrayList<CategoryData>();
}
PCityData.java
package com.panaceasoft.citiesdirectory.models;
import android.os.Parcel;
import android.os.Parcelable;
import java.util.ArrayList;
public class PCityData implements Parcelable {
public int id;
public String name;
public String description;
public String address;
public String lat;
public String lng;
public String added;
public int status;
public int item_count;
public int category_count;
public int sub_category_count;
public int follow_count;
public String cover_image_file;
public int cover_image_width;
public int cover_image_height;
public String cover_image_description;
// public ArrayList<PSubCategoryData> sub_categories;
protected PCityData(Parcel in) {
id = in.readInt();
name = in.readString();
description = in.readString();
address = in.readString();
lat = in.readString();
lng = in.readString();
added = in.readString();
status = in.readInt();
item_count = in.readInt();
category_count = in.readInt();
sub_category_count = in.readInt();
follow_count = in.readInt();
cover_image_file = in.readString();
cover_image_width = in.readInt();
cover_image_height = in.readInt();
cover_image_description = in.readString();
// if (in.readByte() == 0x01) {
// sub_categories = new ArrayList<PSubCategoryData>();
// in.readList(sub_categories, PSubCategoryData.class.getClassLoader());
// } else {
// sub_categories = null;
// }
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(id);
dest.writeString(name);
dest.writeString(description);
dest.writeString(address);
dest.writeString(lat);
dest.writeString(lng);
dest.writeString(added);
dest.writeInt(status);
dest.writeInt(item_count);
dest.writeInt(category_count);
dest.writeInt(sub_category_count);
dest.writeInt(follow_count);
dest.writeString(cover_image_file);
dest.writeInt(cover_image_width);
dest.writeInt(cover_image_height);
dest.writeString(cover_image_description);
//if (sub_categories == null) {
// dest.writeByte((byte) (0x00));
// } else {
// dest.writeByte((byte) (0x01));
// dest.writeList(sub_categories);
// }
}
@SuppressWarnings("unused")
public static final Parcelable.Creator<PCityData> CREATOR = new Parcelable.Creator<PCityData>() {
@Override
public PCityData createFromParcel(Parcel in) {
return new PCityData(in);
}
@Override
public PCityData[] newArray(int size) {
return new PCityData[size];
}
};
}
logcat的
07-12 02:58:33.320 1797-1797/com.panaceasoft.citiesdirectory E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.panaceasoft.citiesdirectory, PID: 1797
java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.panaceasoft.citiesdirectory.models.PCityData
at com.panaceasoft.citiesdirectory.activities.SelectedCategoryActivity$2.onResponse(SelectedCategoryActivity.java:209)
at com.panaceasoft.citiesdirectory.activities.SelectedCategoryActivity$2.onResponse(SelectedCategoryActivity.java:199)
at com.android.volley.toolbox.JsonRequest.deliverResponse(JsonRequest.java:72)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
答案 0 :(得分：0)
我认为以下行包含错误
GlobalData.citydata = (PCityData) gson.fromJson(response.getString("data"), listType);
我认为您正在尝试将gson.fromJson（response.getString（＆＃34; data＆＃34;），listType）转换为PCileData，即ArrayList
答案 1 :(得分：0)
你在这一行上收到错误：
GlobalData.citydata = (PCityData) gson.fromJson(response.getString("data"), listType);
，因为：
gson.fromJson(response.getString("data"), listType);
这会返回一个arraylist并且它不会投射到您的自定义模型中
修复此更改 GlobalData.java 类
public static PCityData citydata = null;
到
public static ArrayList<PCityData> citydata = null;
答案 2 :(得分：0)
Gson gson = new Gson();
Type listType = new TypeToken<List<PCityData>>() {
}.getType();
// Issue is here
GlobalData.citydata = (PCityData) gson.fromJson(response.getString("data"), listType);
修复1：GlobalData.citydat a应为List<PCityData>类型。
修复2：改变如此GlobalData.citydata = (List<PCityData>) gson.fromJson(response.getString("data"), listType);