意圖是不是在我RecyclerView工作

我用這個代碼：意圖是不是在我RecyclerView工作

import android.content.Context; 
import android.content.Intent; 
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.ImageView; 
import android.widget.TextView; 
import java.util.ArrayList; 


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

    public MyAdapter (Context context, ArrayList<PersonData>peopleDataSet) { 
     this.context = context; 
     this.peopleDataSet = peopleDataSet; 
    } 

    Context context; 

    private ArrayList<PersonData> peopleDataSet; 

    public static class MyViewHolder extends RecyclerView.ViewHolder { 



     TextView textViewName; 
     TextView textViewEmail; 
     ImageView imageViewIcon; 
     Button button; 

     public MyViewHolder(View itemView) { 
      super(itemView); 
      this.textViewName = (TextView) itemView.findViewById(R.id.textViewName); 
      this.textViewEmail = (TextView) itemView.findViewById(R.id.textViewEmail); 
      this.imageViewIcon = (ImageView) itemView.findViewById(R.id.imageView); 
      this.button = (Button) itemView.findViewById(R.id.button); 
     } 
    } 

    public MyAdapter(ArrayList<PersonData> people) { 
     this.peopleDataSet = people; 
    } 

    @Override 
    public MyViewHolder onCreateViewHolder(ViewGroup parent, 
              int viewType) { 
     View view = LayoutInflater.from(parent.getContext()) 
       .inflate(R.layout.cards_layout, parent, false); 

     view.setOnClickListener(MainActivity.myOnClickListener); 

     MyViewHolder myViewHolder = new MyViewHolder(view); 
     return myViewHolder; 
    } 

    @Override 
    public void onBindViewHolder(final MyViewHolder holder, final int listPosition) { 

     TextView textViewName = holder.textViewName; 
     final TextView textViewEmail = holder.textViewEmail; 
     ImageView imageView = holder.imageViewIcon; 
     Button button = holder.button; 
     button.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent myIntent = new Intent(context, MainActivity2Activity.class); 
       context.startActivity(myIntent); 
      } 
     }); 
     textViewName.setText(peopleDataSet.get(listPosition).getName()); 
     textViewEmail.setText(peopleDataSet.get(listPosition).getEmail()); 
     imageView.setImageResource(peopleDataSet.get(listPosition).getImage()); 



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

但是，當我按下按鈕，我有以下錯誤： Attempt to invoke virtual method java.lang.String android.content.Context.getPackageName() on a null object reference

而且一個問題，如何識別我的列表中的每個按鈕，以便他們將啓動不同的活動。

MainActivity2Activity.java

import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 


public class MainActivity2Activity extends ActionBarActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main_activity2); 
    } 


    @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_main_activity2, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 
      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
}

logcat的

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference 
      at android.content.ComponentName.<init>(ComponentName.java:77) 
      at android.content.Intent.<init>(Intent.java:4000) 
      at info.osoap.myapplicationzzz.MyAdapter$1.onClick(MyAdapter.java:70) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      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:5221) 
      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:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

MainActivity.java

import android.content.Context; 
import android.os.Bundle; 
import android.support.v7.app.ActionBarActivity; 
import android.support.v7.widget.DefaultItemAnimator; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 
import android.widget.Toast; 

import java.util.ArrayList; 


public class MainActivity extends ActionBarActivity { 

    private static RecyclerView.Adapter adapter; 
    private RecyclerView.LayoutManager layoutManager; 
    private static RecyclerView recyclerView; 
    private static ArrayList<PersonData> people; 
    static View.OnClickListener myOnClickListener; 
    private static ArrayList<Integer> removedItems; 

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




     myOnClickListener = new MyOnClickListener(this); 

     recyclerView = (RecyclerView) findViewById(R.id.my_recycler_view); 
     recyclerView.setHasFixedSize(true); 

     layoutManager = new LinearLayoutManager(this); 
     recyclerView.setLayoutManager(layoutManager); 
     recyclerView.setItemAnimator(new DefaultItemAnimator()); 

     people = new ArrayList<PersonData>(); 
     for (int i = 0; i < MyData.nameArray.length; i++) { 
      people.add(new PersonData(
        MyData.nameArray[i], 
        MyData.emailArray[i], 
        MyData.drawableArray[i], 
        MyData.id_[i] 
      )); 
     } 

     removedItems = new ArrayList<Integer>(); 

     adapter = new MyAdapter(people); 
     recyclerView.setAdapter(adapter); 
    } 


    private static class MyOnClickListener implements View.OnClickListener { 

     private final Context context; 

     private MyOnClickListener(Context context) { 
      this.context = context; 
     } 

     @Override 
     public void onClick(View v) { 
      removeItem(v); 
     } 

     private void removeItem(View v) { 
      int selectedItemPosition = recyclerView.getChildPosition(v); 
      RecyclerView.ViewHolder viewHolder 
        = recyclerView.findViewHolderForPosition(selectedItemPosition); 
      TextView textViewName 
        = (TextView) viewHolder.itemView.findViewById(R.id.textViewName); 
      String selectedName = (String) textViewName.getText(); 
      int selectedItemId = -1; 
      for (int i = 0; i < MyData.nameArray.length; i++) { 
       if (selectedName.equals(MyData.nameArray[i])) { 
        selectedItemId = MyData.id_[i]; 
       } 
      } 
      removedItems.add(selectedItemId); 
      people.remove(selectedItemPosition); 
      adapter.notifyItemRemoved(selectedItemPosition); 
     } 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     super.onCreateOptionsMenu(menu); 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     super.onOptionsItemSelected(item); 
     if (item.getItemId() == R.id.action_add_item) { 
//   check if any items to add 
      if (removedItems.size() != 0) { 
       addRemovedItemToList(); 
      } else { 
       Toast.makeText(this, "Nothing to add", Toast.LENGTH_SHORT).show(); 
      } 
     } 
     return true; 
    } 

    private void addRemovedItemToList() { 
     int addItemAtListPosition = 3; 
     people.add(addItemAtListPosition, new PersonData(
       MyData.nameArray[removedItems.get(0)], 
       MyData.emailArray[removedItems.get(0)], 
       MyData.drawableArray[removedItems.get(0)], 
       MyData.id_[removedItems.get(0)] 
     )); 
     adapter.notifyItemInserted(addItemAtListPosition); 
     removedItems.remove(0); 
    } 
}

來源

2015-04-20 Oleg Mylnikov

顯示代碼在哪裏調用'getPackageName（）''方法 –

可以顯示MainActivity2Activity.java的代碼 –

@ρяσѕρєяK我不在哪裏這個方法位於。我不記得使用它。 –

大概context是null嘗試，因爲：

public void onClick(View v) { 
    Intent myIntent = new Intent(v.getContext(), MainActivity2Activity.class); 
    v.getContext().startActivity(myIntent); 
    }

來源

2015-04-20 06:06:54

現在正在工作，thx很多！ –

在下面的代碼我覺得背景是空，因此你的錯誤更改下面的代碼：

public void onClick(View v) { 
       Intent myIntent = new Intent(context, MainActivity2Activity.class); 
       context.startActivity(myIntent); 
      }

改變上面的代碼：

public void onClick(View v) { 
       Intent myIntent = new Intent(getApplicationContext(), MainActivity2Activity.class); 
       context.startActivity(myIntent); 
      }

或

public void onClick(View v) { 
       Intent myIntent = new Intent(getBaseContext, MainActivity2Activity.class); 
       context.startActivity(myIntent); 
      }

我覺得你是什麼這樣做是不正確的使用onClicks你需要設置一個接口，如下所示：

@Override 
     public void onClick(View view) { 

      if (clickListener != null) { 
       clickListener.itemClicked(view, getPosition()); 
      } 

     } 

public interface ClickListener { 

     public void itemClicked(View view, int position); 
    }

現在您需要在您的活動中實施可以正常工作的界面。嘗試這個。

希望這會有所幫助。

來源

2015-04-20 05:55:38 Keshav1234

既不能解決getApplicationContext，也不getBaseContex –

檢查我的編輯答案。 – Keshav1234

你可以先試試繁榮的答案，然後試試我的。 – Keshav1234

據我所知，RecyclerView不支持點擊的項目子視圖的事件。任何兒童意見事件都被屏蔽。只有RecyclerView.OnItemTouchListener是可以收聽RecyclerView項目的事件。

來源

2015-04-20 06:09:46 SilentKnight

喜打電話給你的適配器，這樣等類

adapter = new MyAdapter(MainActivity.this,people); 
recyclerView.setAdapter(adapter);

您還可以得到view.getContext（）您按鈕的onClick監聽器裏。

我希望它能幫助你解決問題。謝謝。

來源

2015-04-20 06:10:24

意圖是不是在我RecyclerView工作

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