我是改造2的新手，我试图获取json数组数据，但获取null，这是获取数据的网址。
但是有趣的是，当我尝试在onResponse内进行调试时，我收到了成功消息以及response.body数据。这是什么问题？
https://xenzet.com/GameCheat/viewgamesjson.php
这是json数据
[
{
"gameid":"2",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/counter strike 1.6.png",
"Games_Name":"1"
},
{
"gameid":"3",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/gta.ico",
"Games_Name":"vice city sucjlfsdrgefdsrhag"
},
{
"gameid":"4",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/pubg.png",
"Games_Name":"pubg"
},
{
"gameid":"5",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/doom.png",
"Games_Name":"Doom Enternal"
},
{
"gameid":"6",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/for.png",
"Games_Name":"Fornite"
},
{
"gameid":"9",
"gameIcon":"https:\/\/xenzet.com\/GameCheat\/uploads\/dota2.png",
"Games_Name":"dota2"
}
]
这是试图获取数据的方法
public void fetch_information() {
ApiInterface = ApiClient.getApiClient().create(Api.class);
Call<List<Games>> call = ApiInterface.GetGames();
call.enqueue(new Callback<List<Games>>() {
@Override
public void onResponse(Call<List<Games>> call, Response<List<Games>> response) {
if(response.isSuccessful()) {
gameslist = response.body();
gamescounter = gameslist.size();
adapter = new GameRecyclerViewAdapter(GamesActivity.this, gameslist);
recyclerView.setAdapter(adapter);
}
}
@Override
public void onFailure(Call<List<Games>> call, Throwable t) {
Toast.makeText(getApplicationContext(), t.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
这是ApiClient
public class ApiClient {
public static String Base_URL ;
public static Retrofit retrofit;
public static Retrofit getApiClient()
{
if (retrofit == null)
{
Base_URL ="https://xenzet.com/GameCheat/";
retrofit = new Retrofit.Builder().baseUrl(Base_URL)
.addConverterFactory(GsonConverterFactory.create()).build();
}
return retrofit;
}
}
和Api
public interface Api {
@GET("viewgamesjson.php")
Call<List<Games>> GetGames();
}
在OnCreate中，我正在调用获取信息方法。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_games);
gameslist = new ArrayList<Games>();
RecyclerView recyclerView = findViewById(R.id.recyclerview_gameslist);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
fetch_information();
Toast.makeText(getApplicationContext(),"" +gamescounter, Toast.LENGTH_SHORT).show();
adapter = new GameRecyclerViewAdapter(this, gameslist);
recyclerView.setAdapter(adapter);
adapter.setClickListener((GameRecyclerViewAdapter.ItemClickListener) this);
}
试图在回收站视图中填充游戏列表数据，但由于它为空而失败。
这是logcat
2019-05-27 14:03:43.261 1261-1261/com.example.quizgames E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.quizgames, PID: 1261
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)' on a null object reference
at com.example.quizgames.GamesActivity$1.onResponse(GamesActivity.java:109)
at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)
at android.os.Handler.handleCallback(Handler.java:836)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6251)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
这是类游戏
public class Games {
@SerializedName("gameid")
@Expose
private String gameid;
@SerializedName("gameIcon")
@Expose
private String gameIcon;
@SerializedName("Games_Name")
@Expose
private String gamesName;
public String getGameid() {
return gameid;
}
public void setGameid(String gameid) {
this.gameid = gameid;
}
public String getGameIcon() {
return gameIcon;
}
public void setGameIcon(String gameIcon) {
this.gameIcon = gameIcon;
}
public String getGamesName() {
return gamesName;
}
public void setGamesName(String gamesName) {
this.gamesName = gamesName;
}
// public Games(String Gameid,String Gameicon,String GameName)
// {
// this.gameid = Gameid;
// this.gameIcon = Gameicon;
// this.gamesName = GameName;
//
// }
}
这是回收站视图
class GameRecyclerViewAdapter extends RecyclerView.Adapter<GameRecyclerViewAdapter.ViewHolder> {
private List<Games> mGames;
private LayoutInflater mInflater;
private ItemClickListener mClickListener;
// data is passed into the constructor
GameRecyclerViewAdapter(Context context, List<Games> games) {
this.mInflater = LayoutInflater.from(context);
this.mGames = games;
}
// inflates the row layout from xml when needed
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.gameitem, parent, false);
return new ViewHolder(view);
}
// binds the data to the TextView in each row
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Games Game = mGames.get(position);
String Gameid = Game.getGameid();
String Gameicon = Game.getGameIcon();
String Gamename = Game.getGamesName();
holder.GameNameTxt.setText(Gamename);
Glide.with(holder.GameIconImage.getContext()).load(Game.getGameIcon()).thumbnail(0.1f).
placeholder(R.color.colorPrimary).diskCacheStrategy(DiskCacheStrategy.NONE).into(holder.GameIconImage);
}
// total number of rows
@Override
public int getItemCount() {
return mGames == null ? 0 : mGames.size();
}
// stores and recycles views as they are scrolled off screen
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView GameNameTxt;
ImageView GameIconImage;
ViewHolder(View itemView) {
super(itemView);
GameNameTxt = itemView.findViewById(R.id.gamename);
GameIconImage = itemView.findViewById(R.id.imageView);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
}
}
// allows clicks events to be caught
void setClickListener(ItemClickListener itemClickListener) {
this.mClickListener = itemClickListener;
}
// parent activity will implement this method to respond to click events
public interface ItemClickListener {
void onItemClick(View view, int position);
}
}
答案 0 :(得分：0)
在侧面的onResponse方法中向适配器添加数据
在oncreate中添加fetch_information()
@Override
public void onResponse(Call<List<Games>> call, Response<List<Games>> response) {
if(response.isSuccessful()) {
gameslist = response.body();
adapter = new GameRecyclerViewAdapter(MainActivity.this, gameslist);
//change your Activity name here insted of MainActivity
recyclerView.setAdapter(adapter);
}
}
答案 1 :(得分：0)
问题是，您在on gameslist仍然为null的onCreate（）中设置了列表适配器。
adapter = new GameRecyclerViewAdapter(this, gameslist);
recyclerView.setAdapter(adapter);
当您调用setAdapter（）方法时，recyclerView将询问适配器其项目数；我想在getItemCount（）中，您有类似return gameslist.count（）的内容。由于游戏列表仍然为空，因此会导致NPE。
要修复此问题，请将getItemCount（）更改为以下内容：
return gameslist == null ? 0 : gameslist.size()
编辑
我（用邮递员）检查了您的URL，看来响应的内容类型是text/html，而不是应该的application/json。我想因此响应不会使用Gson转换，因此您最终会得到null。
答案 2 :(得分：0)
我没有检查您在哪里犯错。但是此代码实现返回了我在列表中具有10个数据的列表。
public interface APIInterface {
@GET()
Call<List<ViewGame>> viewgamesjson(@Url String url);
}
这是模型类：
public class ViewGame {
String gameid,gameIcon,Games_Name;
public String getGameid() {
return gameid;
}
public void setGameid(String gameid) {
this.gameid = gameid;
}
public String getGameIcon() {
return gameIcon;
}
public void setGameIcon(String gameIcon) {
this.gameIcon = gameIcon;
}
public String getGames_Name() {
return Games_Name;
}
public void setGames_Name(String games_Name) {
Games_Name = games_Name;
}
}
这是APiClient类：
public class APIClient {
static Retrofit retrofit = null;
public static String Base_URL = "https://xenzet.com/GameCheat/";
public static APIInterface getInterface() {
HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient client = new OkHttpClient.Builder()
.readTimeout(60, TimeUnit.SECONDS)
.connectTimeout(60, TimeUnit.SECONDS)
.addInterceptor(interceptor)
.build();
retrofit = new Retrofit.Builder()
.baseUrl(Base_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(client)
.build();
return retrofit.create(APIInterface.class);
}
}
这是API调用：
private void viewGame() {
Call<List<ViewGame>> call = APIClient.getInterface().viewgamesjson("https://xenzet.com/GameCheat/viewgamesjson.php");
call.enqueue(new Callback<List<ViewGame>>() {
@Override
public void onResponse(Call<List<ViewGame>> call, Response<List<ViewGame>> response) {
try {
Global.dismissProgress();
if (response.isSuccessful() && response.body() != null) {
Global.dismissProgress();
Global.printLog("size===", response.body().size() + "");
} else {
Global.dismissProgress();
}
} catch (Exception e) {
e.printStackTrace();
Global.dismissProgress();
}
}
@Override
public void onFailure(Call<List<ViewGame>> call, Throwable t) {
Global.dismissProgress();
try {
Global.showToast(SplashActivity.this, getString(R.string.something_wrong));
} catch (Exception e) {
e.printStackTrace();
}
call.cancel();
t.printStackTrace();
}
});
}