Recycleur View Ne répond pas

Question

Je fais un exemple d'application pour afficher la liste des tickets (Ticket a 2 Textviews et 1 Image View). Premièrement, j'ai essayé avec la vue de liste cela a fonctionné ... Mais le défilement était très moins réactif, donc je pensé à passer à Recycler View.En voyant des tutoriels et des échantillons, je suis venu avec le code ci-dessous.Bien que la construction Gradle est le succès, mais l'application se bloque .... Quelqu'un peut-il m'aider .. !! ??

Cette activité est Mon activité dans laquelle je veux voir ma vue Recycleur.

public class Menu_activity extends AppCompatActivity { 
private List<DataModel> dataModelList = new ArrayList<>(); 
private DataModel mdataModel; 
private Recycle_view mRecycleview; 
RecyclerView recyclerView; 

@Override 
    protected void onCreate(@Nullable Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.third_layout); 
    recyclerView = (RecyclerView) findViewById(R.id.recyclerview); 
    RecyclerView.LayoutManager mlayoutManager = new 
    LinearLayoutManager(this); 
    recyclerView.setLayoutManager(mlayoutManager); 
    recyclerView.setItemAnimator(new DefaultItemAnimator()); 
    recyclerView.setAdapter(mRecycleview); 
    prepareData(); 
} 

C'est ma fonction de données

private void prepareData(){ 

    DataModel dataModel = new DataModel("Mad Max: Fury Road", R.drawable.ic4, "Action & Adventure"); 
    dataModelList.add(dataModel); 

    dataModel = new DataModel("Inside Out", R.drawable.ic5,"Animation, Kids & Family"); 
    dataModelList.add(dataModel); 

    dataModel = new DataModel("Star Wars: Episode VII - The Force Awakens", R.drawable.ic6, "Action"); 
    dataModelList.add(dataModel); 

    dataModel = new DataModel("Shaun the Sheep", R.drawable.ic7, "Animation"); 
    dataModelList.add(dataModel);`` 

    dataModel = new DataModel("The Martian", R.drawable.app_icon, "Science Fiction & Fantasy"); 
    dataModelList.add(dataModel); 

    dataModel = new DataModel("Mission: Impossible Rogue Nation", R.drawable.iconic, "Action"); 
    dataModelList.add(dataModel); 
    mdataModel.notify(); 

Ceci est mon recycleur Voir Adaptateur

public class Recycle_view extends 
    RecyclerView.Adapter<Recycle_view.MyViewHolder> { 

     private List<DataModel> dataModelList; 

    public Recycle_view(List<DataModel> dataModelList){ 
     this.dataModelList = dataModelList; 
    } 

    @Override 
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
     View itemView = LayoutInflater.from(parent.getContext()) 
      .inflate(R.layout.list_icy_ticket, parent, false); 
     return new MyViewHolder(itemView); 
    } 

    @Override 
    public void onBindViewHolder(MyViewHolder holder, int position) { 
     DataModel dataModel = dataModelList.get(position); 
     holder.heads.setText(dataModel.getHead()); 
     holder.descs.setText(dataModel.getDesc()); 
     holder.images.setImageResource(dataModel.getImage()); 
    } 

    @Override 
    public int getItemCount() { 
     return dataModelList.size(); 
    } 

    public class MyViewHolder extends RecyclerView.ViewHolder { 

    public TextView heads,descs; 
    public ImageView images; 

    public MyViewHolder(View itemView) { 
     super(itemView); 
     heads = (TextView)itemView.findViewById(R.id.textView_head); 
     descs = (TextView)itemView.findViewById(R.id.textView_desc); 
     images = (ImageView) itemView.findViewById(R.id.imageView4); 
    } 
} 
} 

C'est MyData Modèle

public class DataModel { 

    private String head; 
    private String desc; 
    private int image; 
    public DataModel(String head, int image, String desc){ 
     this.head=head; 
     this.desc=desc; 
     this.image=image; 
    } 

    public String getHead() { 
     return head; 
    } 

    public void setHead(String head) { 
     this.head = head; 
    } 

    public String getDesc() { 
     return desc; 
    } 

    public void setDesc(String head) { 
     this.desc = desc; 
    } 

    public int getImage(){ 
     return image; 
    } 
    public void setImage(int image){ 
     this.image = image; 
    } 
} 

Le présent rapport est crash

08-28 20:05:09.281 1700-1714/system_process W/ActivityManager: Force finishing activity com.example.mishr.icycandy/.Menu_activity 
    08-28 20:05:09.353 1700-3581/system_process I/OpenGLRenderer: Initialized EGL, version 1.4 
    08-28 20:05:09.353 1700-3581/system_process D/OpenGLRenderer: Swap behavior 1 
    08-28 20:05:09.353 1700-3581/system_process W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without... 
    08-28 20:05:09.353 1700-3581/system_process D/OpenGLRenderer: Swap behavior 0 
    08-28 20:05:09.358 1700-3581/system_process D/EGL_emulation: eglCreateContext: 0x96f78b80: maj 2 min 0 rcv 2 
    08-28 20:05:09.375 1700-3581/system_process D/EGL_emulation: eglMakeCurrent: 0x96f78b80: ver 2 0 (tinfo 0x96618ad0) 
    08-28 20:05:09.388 1700-3581/system_process D/EGL_emulation: eglMakeCurrent: 0x96f78b80: ver 2 0 (tinfo 0x96618ad0) 
    08-28 20:05:09.792 1700-1716/system_process W/ActivityManager: Activity pause timeout for ActivityRecord{cd3b7f u0 com.example.mishr.icycandy/.Menu_activity t37 f} 
    08-28 20:05:11.181 1700-1700/system_process W/WindowManager: Attempted to remove non-existing token: android.os.Binder@cd37caa 
    08-28 20:05:12.364 1378-1409/? W/audio_hw_generic: Not supplying enough data to HAL, expected position 1978693 , only wrote 1826640 
FATAL EXCEPTION: main 
Process: com.example.mishr.icycandy, PID: 17572 
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mishr.icycandy/com.example.mishr.icycandy.Menu_activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.lang.Object.notify()' on a null object reference 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.lang.Object.notify()' on a null object reference 
at com.example.mishr.icycandy.Menu_activity.prepareData(Menu_activity.java:104) 
at com.example.mishr.icycandy.Menu_activity.onCreate(Menu_activity.java:81) 
at android.app.Activity.performCreate(Activity.java:6679) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)  
at android.app.ActivityThread.-wrap12(ActivityThread.java)  
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)  
at android.os.Handler.dispatchMessage(Handler.java:102)  
at android.os.Looper.loop(Looper.java:154)  
at android.app.ActivityThread.main(ActivityThread.java:6119)  
at java.lang.reflect.Method.invoke(Native Method)  
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)  

Answer 1

d'abord initialiser le mRecycleView et simplement supprimer

mDataMode.notify(); 

et écrire

mRecycleView.nofityDataSetChanged(); 

et le changement du code pour la classe d'adaptateur

public class Recycle_view extends 
    RecyclerView.Adapter<Recycle_view.MyViewHolder> { 
    } 
    @Override 
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View itemView = LayoutInflater.from(parent.getContext()) 
      .inflate(R.layout.list_icy_ticket, parent, false); 

    return new MyViewHolder(itemView); 
} 

@Override 
public void onBindViewHolder(MyViewHolder holder, int position) { 
    DataModel dataModel = dataModelList.get(position); 
    holder.heads.setText(dataModel.getHead()); 
    holder.descs.setText(dataModel.getDesc()); 
    holder.images.setImageResource(dataModel.getImage()); 

} 

@Override 
public int getItemCount() { 
    return dataModelList.size(); 
} 

public class MyViewHolder extends RecyclerView.ViewHolder { 
    public TextView heads,descs; 
    public ImageView images; 

    public MyViewHolder(View itemView) { 
     super(itemView); 
     heads = (TextView)itemView.findViewById(R.id.textView_head); 
     descs = (TextView)itemView.findViewById(R.id.textView_desc); 
     images = (ImageView) itemView.findViewById(R.id.imageView4); 
    } 


} 
} 

et une chose il suffit d'utiliser imageloader comme glide pour un défilement rapide ...

Answer 2

Cette ligne explique où vous avez une erreur:

java.lang.NullPointerException: Attempt to invoke virtual method 'void java.lang.Object.notify()' on a null object reference

Donc vous n'avez pas initialiser votre mdataModel. Et avez-vous besoin de cette ligne de code? Quel est le but de mdataModel.notify(); En fait, vous avez plusieurs problèmes dans votre code. Vous obtiendrez probablement une autre exception car vous n'avez pas initialisé la classe d'adaptateur et vous n'avez pas transmis les données à l'adaptateur. La seconde vous manque Context dans votre classe d'adaptateur.

private List<DataModel> prepareData() { 
    // your code 
    return dataModelList; 
} 

dans votre classe d'adaptateur:

Context context; 

public Recycle_view(Context context,List<DataModel> dataModelList){ 
     this.context = context; 
     this.dataModelList = dataModelList; 
    } 

Retour à votre Menu_activity

mRecycleview = new Recycle_view (this, prepareData()); 
recyclerView.setAdapter(mRecycleview); 

Answer 3

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

    //I guess you do not need mdatamodel please remove it in your prepareData() method if you feel you still need it 
    mdatamodel = new DataModel(head,image,desc); 
    //define head, image and desc and use it above. 
    prepareData(); // Your data model will be ready 
    recyclerView = (RecyclerView) findViewById(R.id.recyclerview); 
    RecyclerView.LayoutManager mlayoutManager = new 
    LinearLayoutManager(this); 
    recyclerView.setLayoutManager(mlayoutManager); 
    recyclerView.setItemAnimator(new DefaultItemAnimator()); 
    mRecyclerview = new Recycle_View(dataModelList); 
    recyclerView.setAdapter(mRecycleview); 
}