java.util.ArrayList 不能强制转换为
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【中文标题】java.util.ArrayList 不能强制转换为【英文标题】：java.util.ArrayList cannot be cast to 【发布时间】：2015-09-03 07:04:39 【问题描述】：我是 android 新手，在不同的测试应用程序中测试我的技能。现在我正在尝试从 Json url 获取数据并从 Json 的对象收藏列表中创建。 Gradle 完成后没有任何问题，但每次我的应用启动时，它都会崩溃并出现下一个错误：
尝试在空对象引用上调用接口方法“int java.util.List.size()”
我用作教程的下一个资源：
对于共享首选项：http://androidopentutorials.com/android-how-to-store-list-of-values-in-sharedpreferences/
对于 Json 解析器：http://www.androidhive.info/2014/09/android-json-parsing-using-volley/
这是我的代码错误和活动错误在哪里：
06-17 17:05:14.124 10249-10249/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.boom.kayakapp, PID: 10249
java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.boom.kayakapp.model.Airlines
at com.boom.kayakapp.adapters.AirlinesListAdapter.getView(AirlinesListAdapter.java:102)
at android.widget.AbsListView.obtainView(AbsListView.java:2347)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1270)
at android.widget.ListView.onMeasure(ListView.java:1182)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:444)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
at android.view.View.measure(View.java:17547)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2015)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1173)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1379)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
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:5257)
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)
06-17 17:05:14.153 932-932/? E/EGL_emulation﹕ tid 932: eglCreateSyncKHR(1237): error 0x3004 (EGL_BAD_ATTRIBUTE)
06-17 17:05:16.543 1233-1266/system_process E/InputDispatcher﹕ channel '26e93136 com.boom.kayakapp/com.boom.kayakapp.activities.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
06-17 17:05:38.432 10506-10506/? E/memtrack﹕ Couldn't load memtrack module (No such file or directory)
06-17 17:05:38.432 10506-10506/? E/android.os.Debug﹕ failed to load memtrack module: -2
06-17 17:05:39.009 10523-10523/? E/memtrack﹕ Couldn't load memtrack module (No such file or directory)
06-17 17:05:39.009 10523-10523/? E/android.os.Debug﹕ failed to load memtrack module: -2
06-17 17:05:51.855 10533-10533/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.boom.kayakapp, PID: 10533
java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.boom.kayakapp.model.Airlines
at com.boom.kayakapp.adapters.AirlinesListAdapter.getView(AirlinesListAdapter.java:102)
at android.widget.AbsListView.obtainView(AbsListView.java:2347)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1270)
at android.widget.ListView.onMeasure(ListView.java:1182)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:444)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17547)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
at android.view.View.measure(View.java:17547)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2015)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1173)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1379)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
06-17 17:05:51.887 932-932/? E/EGL_emulation﹕ tid 932: eglCreateSyncKHR(1237): error 0x3004 (EGL_BAD_ATTRIBUTE)
06-17 17:06:51.514 11046-11046/? E/memtrack﹕ Couldn't load memtrack module (No such file or directory)
06-17 17:06:51.514 11046-11046/? E/android.os.Debug﹕ failed to load memtrack module: -2
06-17 17:06:52.206 11063-11063/? E/memtrack﹕ Couldn't load memtrack module (No such file or directory)
06-17 17:06:52.207 11063-11063/? E/android.os.Debug﹕ failed to load memtrack module: -2
06-17 17:07:03.184 932-932/? E/EGL_emulation﹕ tid 932: eglCreateSyncKHR(1237): error 0x3004 (EGL_BAD_ATTRIBUTE)
06-17 17:07:06.919 1233-1266/system_process E/InputDispatcher﹕ channel '3bd6cfb7 com.boom.kayakapp/com.boom.kayakapp.activities.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
AirlinesListAdapter：
package com.boom.kayakapp.adapters;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.NetworkImageView;
import com.boom.kayakapp.R;
import com.boom.kayakapp.controllers.AppController;
import com.boom.kayakapp.model.Airlines;
import com.boom.kayakapp.util.SharedPreference;
import java.util.ArrayList;
import java.util.List;
public class AirlinesListAdapter extends ArrayAdapter<Airlines>
private Activity activity;
private List<Airlines> favorites;
private LayoutInflater inflater;
SharedPreference sharedPreference;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public AirlinesListAdapter(Activity activity, List<Airlines> favorites)
super(activity, R.layout.list_item, favorites);
this.activity = activity;
if(favorites == null)
favorites = new ArrayList<>();
else
this.favorites = favorites;
sharedPreference = new SharedPreference();
private class ViewHolder
ImageView favoriteImg;
@Override
public int getCount()
return favorites.size();
@Override
public Airlines getItem(int location)
return favorites.get(location);
@Override
public long getItemId(int position)
return 0;
@Override
public View getView(int position, View convertView, ViewGroup parent)
ViewHolder holder = null;
if (inflater == null)
inflater = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_item, null);
holder = new ViewHolder();
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView logoURL = (NetworkImageView) convertView
.findViewById(R.id.logoURL);
TextView name = (TextView) convertView.findViewById(R.id.name);
TextView phone = (TextView) convertView.findViewById(R.id.phone);
TextView site = (TextView) convertView.findViewById(R.id.site);
TextView code = (TextView) convertView.findViewById(R.id.code);
holder.favoriteImg = (ImageView) convertView
.findViewById(R.id.favorite_button);
// getting airlines data for the row
Airlines m = favorites.get(position);
// thumbnail image
logoURL.setImageUrl(m.getLogoURL(), imageLoader);
// name
name.setText(m.getName());
// phone
phone.setText("Phone: " + String.valueOf(m.getPhone()));
// site
site.setText("Web: " + String.valueOf(m.getSite()));
// release code
code.setText(String.valueOf(m.getCode()));
/*If a product exists in shared preferences then set heart_red drawable
* and set a tag*/
if (checkFavoriteItem((Airlines) favorites))
holder.favoriteImg.setImageResource(R.drawable.heart_red);
holder.favoriteImg.setTag("red");
else
holder.favoriteImg.setImageResource(R.drawable.heart_grey);
holder.favoriteImg.setTag("grey");
return convertView;
/*Checks whether a particular product exists in SharedPreferences*/
public boolean checkFavoriteItem(Airlines checkAirlines)
boolean check = false;
// List<Airlines> favorites = sharedPreference.getFavorites(activity);
if (favorites != null)
for (Airlines product : favorites)
if (product.equals(checkAirlines))
check = true;
break;
return check;
@Override
public void add(Airlines airlines)
super.add(airlines);
favorites.add(airlines);
notifyDataSetChanged();
@Override
public void remove(Airlines airlines)
super.remove(airlines);
favorites.remove(airlines);
notifyDataSetChanged();
AirlineListFragment：
package com.boom.kayakapp.fragment;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;
import com.boom.kayakapp.R;
import com.boom.kayakapp.adapters.AirlinesListAdapter;
import com.boom.kayakapp.model.Airlines;
import com.boom.kayakapp.util.SharedPreference;
import java.util.ArrayList;
import java.util.List;
public class AirlinesListFragment extends Fragment implements OnItemLongClickListener, AdapterView.OnItemClickListener
public static final String ARG_ITEM_ID = "airlines_list";
Activity activity;
ListView airlinesListView;
List<Airlines> airlines;
AirlinesListAdapter airlinesListAdapter;
public AirlinesListFragment()
airlines = new ArrayList<>();
SharedPreference sharedPreference;
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
activity = getActivity();
sharedPreference = new SharedPreference();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View view = inflater.inflate(R.layout.fragment_airlines_list, container,
false);
findViewsById(view);
airlinesListAdapter = new AirlinesListAdapter(activity, airlines);
airlinesListView.setAdapter(airlinesListAdapter);
airlinesListView.setOnItemClickListener(this);
airlinesListView.setOnItemLongClickListener(this);
return view;
private void findViewsById(View view)
airlinesListView = (ListView) view.findViewById(R.id.list_airlines);
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id)
Airlines airlines = (Airlines) parent.getItemAtPosition(position);
Toast.makeText(activity, airlines.toString(), Toast.LENGTH_LONG).show();
@Override
public boolean onItemLongClick(AdapterView<?> arg0, View view,
int position, long arg3)
ImageView button = (ImageView) view.findViewById(R.id.favorite_button);
String tag = button.getTag().toString();
if (tag.equalsIgnoreCase("grey"))
sharedPreference.addFavorite(activity, airlines.get(position));
Toast.makeText(activity,
activity.getResources().getString(R.string.add_favr),
Toast.LENGTH_SHORT).show();
button.setTag("red");
button.setImageResource(R.drawable.heart_red);
else
sharedPreference.removeFavorite(activity, airlines.get(position));
button.setTag("grey");
button.setImageResource(R.drawable.heart_grey);
Toast.makeText(activity,
activity.getResources().getString(R.string.remove_favr),
Toast.LENGTH_SHORT).show();
return true;
@Override
public void onResume()
getActivity().setTitle(R.string.app_name);
getActivity().getActionBar().setTitle(R.string.app_name);
super.onResume();
主活动：
package com.boom.kayakapp.activities;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonArrayRequest;
import com.boom.kayakapp.R;
import com.boom.kayakapp.adapters.AirlinesListAdapter;
import com.boom.kayakapp.controllers.AppController;
import com.boom.kayakapp.fragment.AirlinesListFragment;
import com.boom.kayakapp.fragment.FavoriteListFragment;
import com.boom.kayakapp.model.Airlines;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends ActionBarActivity
private Fragment contentFragment;
AirlinesListFragment airlinesListFragment;
FavoriteListFragment favoriteListFragment;
// JSON Node names
public static final String TAG_NAME = "name";
public static final String TAG_PHONE = "phone";
public static final String TAG_SITE = "site";
public static final String TAG_LOGO = "logoURL";
public static final String TAG_CODE = "code";
// Log tag
private static final String TAG = MainActivity.class.getSimpleName();
// Airlines json url
private static final String url = "https://www.kayak.com/h/mobileapis/directory/airlines";
public ProgressDialog pDialog;
public List<Airlines> airlinesList = new ArrayList<Airlines>();
public ListView listView;
public AirlinesListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.list);
adapter = new AirlinesListAdapter(this, airlinesList);
listView.setAdapter(adapter);
pDialog = new ProgressDialog(this);
// Showing progress dialog before making http request
pDialog.setMessage("Loading...");
pDialog.show();
// Listview on item click listener
listView.setOnItemClickListener(new AdapterView.OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id)
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String phone = ((TextView) view.findViewById(R.id.phone))
.getText().toString();
String site = ((TextView) view.findViewById(R.id.site))
.getText().toString();
String logoURL = String.valueOf(((ImageView) view.findViewById(R.id.logoURL)));
// Starting single contact activity
Intent in = new Intent(getApplicationContext(),
SingleContactActivity.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_PHONE, phone);
in.putExtra(TAG_SITE, site);
in.putExtra(TAG_LOGO, logoURL);
startActivity(in);
);
// changing action bar color
getSupportActionBar().setBackgroundDrawable(
new ColorDrawable(Color.parseColor("#1b1b1b")));
// Creating volley request obj
JsonArrayRequest airlinesReq = new JsonArrayRequest(url,
new Response.Listener<JSONArray>()
@Override
public void onResponse(JSONArray response)
Log.d(TAG, response.toString());
hidePDialog();
// Parsing json
for (int i = 0; i < response.length(); i++)
try
JSONObject obj = response.getJSONObject(i);
Airlines airlines = new Airlines();
airlines.setName(obj.getString("name"));
airlines.setLogoURL(obj.getString("logoURL"));
airlines.setPhone(obj.getString("phone"));
airlines.setCode(obj.getInt("code"));
airlines.setSite(obj.getString("site"));
// adding airlines to movies array
airlinesList.add(airlines);
catch (JSONException e)
e.printStackTrace();
// notifying list adapter about data changes
// so that it renders the list view with updated data
adapter.notifyDataSetChanged();
, new Response.ErrorListener()
@Override
public void onErrorResponse(VolleyError error)
VolleyLog.d(TAG, "Error: " + error.getMessage());
hidePDialog();
);
// Adding request to request queue
AppController.getInstance().addToRequestQueue(airlinesReq);
FragmentManager fragmentManager = getSupportFragmentManager();
/*
* This is called when orientation is changed.
*/
if (savedInstanceState != null)
if (savedInstanceState.containsKey("content"))
String content = savedInstanceState.getString("content");
if (content.equals(FavoriteListFragment.ARG_ITEM_ID))
if (fragmentManager.findFragmentByTag(FavoriteListFragment.ARG_ITEM_ID) != null)
setFragmentTitle(R.string.favorites);
contentFragment = fragmentManager
.findFragmentByTag(FavoriteListFragment.ARG_ITEM_ID);
if (fragmentManager.findFragmentByTag(AirlinesListFragment.ARG_ITEM_ID) != null)
airlinesListFragment = (AirlinesListFragment) fragmentManager
.findFragmentByTag(AirlinesListFragment.ARG_ITEM_ID);
contentFragment = airlinesListFragment;
else
airlinesListFragment = new AirlinesListFragment();
// setFragmentTitle(R.string.app_name);
switchContent(airlinesListFragment, AirlinesListFragment.ARG_ITEM_ID);
@Override
public void onDestroy()
super.onDestroy();
hidePDialog();
private void hidePDialog()
if (pDialog != null)
pDialog.dismiss();
pDialog = null;
@Override
public boolean onCreateOptionsMenu(Menu menu)
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
@Override
protected void onSaveInstanceState(Bundle outState)
if (contentFragment instanceof FavoriteListFragment)
outState.putString("content", FavoriteListFragment.ARG_ITEM_ID);
else
outState.putString("content", AirlinesListFragment.ARG_ITEM_ID);
super.onSaveInstanceState(outState);
// @Override
// public boolean onCreateOptionsMenu(Menu menu)
// getMenuInflater().inflate(R.menu.main, menu);
// return true;
//
@Override
public boolean onOptionsItemSelected(MenuItem item)
switch (item.getItemId())
case R.id.menu_favorites:
setFragmentTitle(R.string.favorites);
favoriteListFragment = new FavoriteListFragment();
switchContent(favoriteListFragment, FavoriteListFragment.ARG_ITEM_ID);
return true;
return super.onOptionsItemSelected(item);
public void switchContent(Fragment fragment, String tag)
FragmentManager fragmentManager = getSupportFragmentManager();
while (fragmentManager.popBackStackImmediate());
if (fragment != null)
FragmentTransaction transaction = fragmentManager
.beginTransaction();
transaction.replace(R.id.content_frame, fragment, tag);
//Only FavoriteListFragment is added to the back stack.
if (!(fragment instanceof AirlinesListFragment))
transaction.addToBackStack(tag);
transaction.commit();
contentFragment = fragment;
protected void setFragmentTitle(int resourseId)
setTitle(resourseId);
getSupportActionBar().setTitle(resourseId);
/*
* We call super.onBackPressed(); when the stack entry count is > 0. if it
* is instanceof ProductListFragment or if the stack entry count is == 0, then
* we finish the activity.
* In other words, from ProductListFragment on back press it quits the app.
*/
@Override
public void onBackPressed()
FragmentManager fm = getSupportFragmentManager();
if (fm.getBackStackEntryCount() > 0)
super.onBackPressed();
else if (contentFragment instanceof AirlinesListFragment
|| fm.getBackStackEntryCount() == 0)
finish();
型号：
package com.boom.kayakapp.model;
public class Airlines
private String name, logoURL, phone, site;
private int code;
public Airlines()
public Airlines
(String name, String logoURL, int code, String phone, String site)
this.name = name;
this.logoURL = logoURL;
this.code = code;
this.phone = phone;
this.site = site;
public String getName() return name;
public void setName(String name) this.name = name;
public String getLogoURL() return logoURL;
public void setLogoURL(String logoURL) this.logoURL = logoURL;
public int getCode() return code;
public void setCode(Integer code) this.code = code;
public String getPhone() return phone;
public void setPhone(String phone) this.phone = phone;
public String getSite() return site;
public void setSite(String site) this.site = site;
【问题讨论】：
【参考方案1】：setAdapter 调用 getCount 但列表为空，所以只需像这样初始化航空公司列表
public AirlinesListAdapter(Activity activity, List<Airlines> favorites)
super(activity, R.layout.list_item, favorites);
this.activity = activity;
if(favorites == null)
favorites = new ArrayList<>();
else
this.favorites = favorites;
sharedPreference = new SharedPreference();
第二种解决方案： 在片段中初始化数组
public AirlinesListFragment()
airlines = new ArrayList<>();
这应该可以解决您的问题
查看此页面以获取解决方案：Can't get Action Bar in fragment class
【讨论】：
第二种方式对我有帮助，非常感谢！但不幸的是它显示了另一个错误，但我继续前进，感谢帮助！！！ 好的，用新的错误更新你的问题，我会尽力帮助你 Itzik Samara，谢谢你的帮助，但我只是在 AirlinesListFragment 中评论 getActivity().getActionBar().setTitle(R.string.app_name); b> 因为它与第一个字符串 getActivity().setTitle(R.string.app_name); 重复，然后应用程序向我显示了下一个错误（听起来像诅咒）错误我与新模型活动一起更新 你的问题在这里 checkFavoriteItem((Airlines) favorites) 最喜欢的是 List 并且你只需要 Airlines以上是关于java.util.ArrayList 不能强制转换为的主要内容，如果未能解决你的问题，请参考以下文章
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