Impossibile impostare OnCheckedChangeListener su una casella di controllo

Question

Sto provando a impostare OnCheckedChangeListener su CheckBox ma la mia richiesta termina nel tempo di esecuzione. Ho anche provato a impostare gli ascoltatori per il mio TextView e ottengo lo stesso risultato. Qualcuno può aiutare?

import android.app.ListActivity; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.DialogInterface.OnClickListener; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.CheckBox; 
import android.widget.CompoundButton; 
import android.widget.CompoundButton.OnCheckedChangeListener; 
import android.widget.ImageView; 
import android.widget.ListView; 
import android.widget.TextView; 
import android.widget.Toast; 

public class ListViewActivity extends ListActivity implements OnCheckedChangeListener { 

TextView label; 
CheckBox checkBox; 

public class MyCustomAdapter extends ArrayAdapter<String> { 


public MyCustomAdapter(Context context, int textViewResourceId, 
String[] objects) { 
super(context, textViewResourceId, objects); 

// TODO Auto-generated constructor stub 
} 

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
// TODO Auto-generated method stub 
//return super.getView(position, convertView, parent); 

View row = convertView; 

if(row==null){ 
LayoutInflater inflater=getLayoutInflater(); 
row=inflater.inflate(R.layout.main, parent, false); 

} 


label=(TextView)row.findViewById(R.id.weekofday); 
label.setText(month[position]); 
checkBox=(CheckBox)row.findViewById(R.id.checkBox); 


return row; 
} 
} 

String[] month = { 
"January", "February", "March", "April", 
"May", "June", "July", "August", 
"September", "October", "November", "December" 
}; 

/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
// setContentView(R.layout.main); 
/*setListAdapter(new ArrayAdapter<String>(this, 
    R.layout.row, R.id.weekofday, DayOfWeek));*/ 


    setListAdapter(new MyCustomAdapter(ListViewActivity.this, R.layout.main, month)); 

    checkBox.setOnCheckedChangeListener(this); //my application exits here!!!! 

} 





@Override 
public void onCheckedChanged(CompoundButton arg0, boolean arg1) { 
// TODO Auto-generated method stub 
//Toast.makeText(getApplicationContext(), "box checked", Toast.LENGTH_LONG); 

} 


} 

Answer 1

Non è possibile impostare l'ascoltatore per la CheckBox dalla ListView come quella (probabilmente gettare un NullPointerException), invece impostare l'ascoltatore nel metodo getView() (dovrete anche per mantenere lo stato CheckBox quindi non si finisce con lo stato di righe strane). Bellow è un esempio:

public class ListViewActivity extends ListActivity { 

    public class MyCustomAdapter extends ArrayAdapter<String> { 

     private ArrayList<Boolean> status = new ArrayList<Boolean>(); 

     public MyCustomAdapter(Context context, int textViewResourceId, 
       String[] objects) { 
      super(context, textViewResourceId, objects); 
      for (int i = 0; i < objects.length; i++) { 
       status.add(false); 
      } 
     } 

     @Override 
     public View getView(final int position, View convertView, 
       ViewGroup parent) { 
      View row = convertView; 
      if (row == null) { 
       LayoutInflater inflater = getLayoutInflater(); 
       row = inflater.inflate(R.layout.adapters_listviewactivity_row, 
         parent, false); 
      } 

      TextView label = (TextView) row.findViewById(R.id.weekofday); 
      label.setText(month[position]); 
      CheckBox checkBox = (CheckBox) row.findViewById(R.id.checkBox); 
      checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() { 

       @Override 
       public void onCheckedChanged(CompoundButton buttonView, 
         boolean isChecked) { 
        Toast.makeText(getApplicationContext(), "" + position, 
          Toast.LENGTH_SHORT).show(); 
        if (isChecked) { 
         status.set(position, true); 
        } else { 
         status.set(position, false); 
        } 
       } 
      }); 
      checkBox.setChecked(status.get(position)); 
      return row; 
     } 
    } 

    String[] month = { "January", "February", "March", "April", "May", "June", 
      "July", "August", "September", "October", "November", "December" }; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setListAdapter(new MyCustomAdapter(ListViewActivity.this, 
       R.layout.main, month)); 
    } 

} 

Per il TextView dovrete fare la stessa cosa.

Answer 2

Implementare CheckBox Listener per la classe in questo modo, soprattutto se si dispone di più di una casella di controllo per affrontare, è possibile gestire nel caso in cui i blocchi switch e rende il codice più ordinato:

public class MyClass extends AppCompatActivity implements 
    CompoundButton.OnCheckedChangeListener,{ 

     CheckBox myCheckBox; 
    } 

Nella tua metodo onCreate() ha messo questa:

myCheckBox = (CheckBox)findViewById(R.Id.myCheckBoxName_in_XML_layout); 
    mmyCheckBox.setOnCheckedChangeListener(this); 

Listern per la vostra casella di visualizzazione evento come questo:

@Override 
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 

    switch (buttonView.getId()){ 
     case R.id.myCheckBoxName_in_XML_layout: 

      if(isChecked == true) { 
       Toast.makeText(this, "Checked", Toast.LENGTH_SHORT).show(); 
      } else{ 
        Toast.makeText(this, "Unchecked", Toast.LENGTH_SHORT).show(); 
        } 

      break; 
     } 

     } 

Answer 3

public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener { 
List<String> mList = new ArrayList<>(); 
CheckBox android, java, python, php, unity3D; 
Button submitButton; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    android = (CheckBox) findViewById(R.id.androidCheckBox); 
    android.setOnCheckedChangeListener(this); 
    java = (CheckBox) findViewById(R.id.javaCheckBox); 
    java.setOnCheckedChangeListener(this); 
    python = (CheckBox) findViewById(R.id.pythonCheckBox); 
    python.setOnCheckedChangeListener(this); 
    php = (CheckBox) findViewById(R.id.phpCheckBox); 
    php.setOnCheckedChangeListener(this); 
    unity3D = (CheckBox) findViewById(R.id.unityCheckBox); 
    unity3D.setOnCheckedChangeListener(this); 

    submitButton = (Button) findViewById(R.id.submitButton); 
    submitButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Log.e("ArrayList Values*******",mList.toString()); 
     } 
    }); 

} 

@Override 
public void onCheckedChanged(CompoundButton compoundButton, boolean b) { 
    switch (compoundButton.getId()) { 
     case R.id.androidCheckBox: 
      if (android.isChecked()) { 
       mList.add(String.valueOf(android.getText())); 
       Log.e("Android*******",mList.toString()); 
      } 
      else { 
        mList.remove(android.getText()); 
      } 
      break; 

     case R.id.javaCheckBox: 
      if (java.isChecked()) { 
       mList.add(String.valueOf(java.getText())); 
       Log.e("Java*******",mList.toString()); 
      } 
      else { 
       mList.remove(java.getText()); 
      } 
      break; 

     case R.id.phpCheckBox: 
      if (php.isChecked()) { 
       mList.add(String.valueOf(php.getText())); 
       Log.e("PHP*******",mList.toString()); 
      } 
      else { 
       mList.remove(php.getText()); 
      } 
      break; 

     case R.id.pythonCheckBox: 
      if (python.isChecked()){ 
       mList.add(String.valueOf(python.getText())); 
       Log.e("Python*******",mList.toString()); 
      } 
      else { 
       mList.remove(python.getText()); 
      } 
      break; 

     case R.id.unityCheckBox: 
      if (unity3D.isChecked()){ 
       mList.add(String.valueOf(unity3D.getText())); 
       Log.e("Unity*******",mList.toString()); 
      } 
      else { 
       mList.remove(unity3D.getText()); 
      } 
      break; 
     } 
    } 
}