共有環境設定でチェックボックスの値を保存するにはどうすればよいですか？

Question

私のコードが保存されない理由が分かりませんcheckboxチェックされた値。 checkboxをチェックして、別のタブをクリックして前のタブに戻ると、checkboxが選択されていません...私のコードでエラーが見つかったら幸いです！

IDEは私に言う：FATAL EXCEPTION: main java.lang.NullPointerException at line ".onCreateView(holder.chkBox.setChecked(true);"

なぜ？その後、

ListView lv; 
ArrayList<Planet> planetList; 
PlanetAdapter plAdapter; 
BirraAdapter biAdapter; 
PlanetAdapter.PlanetHolder holder; 



public class MyListFragment extends Fragment implements 
     android.widget.CompoundButton.OnCheckedChangeListener { 

    ListView lv; 
    ArrayList<Planet> planetList; 
    PlanetAdapter plAdapter; 
    BirraAdapter biAdapter; 
    PlanetAdapter.PlanetHolder holder; 



    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 

     ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_list2, container, false); 
     //@Override 

     /* SharedPreferences preferences = getContext().getSharedPreferences("MaterialTabs", android.content.Context.MODE_PRIVATE); 
      boolean mCheckBoxValue = preferences.getBoolean("CheckBox_Value", false); 

      if (mCheckBoxValue) { 
      holder.chkBox.setChecked(true); 


      } else { 
       holder.chkBox.setChecked(false); 

     }*/ 


     Button mButton = (Button) rootView.findViewById(R.id.button); 
     mButton.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View v) { 
      showResult(v); 


      } 
     }); 
     //return inflater.inflate(R.layout.fragment_list2, container, false); 
     return rootView; 
    } 


    @Override 
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { 
     super.onViewCreated(view, savedInstanceState); 


     lv = (ListView)getView().findViewById(R.id.listview); 
     displayPlanetList(); 
    } 


    private void displayPlanetList() { 

     planetList = new ArrayList<Planet>(); 
     planetList.add(new Planet("Margherita", 6, "€")); 
     planetList.add(new Planet("Diavola", 7,"€")); 
     planetList.add(new Planet("Bufalina", 5,"€")); 
     planetList.add(new Planet("Marinara", 5,"€")); 
     planetList.add(new Planet("Viennese", 4, "€")); 

     plAdapter = new PlanetAdapter(planetList, getContext()) { 
      @Override 
      public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 

       int pos = lv.getPositionForView(buttonView); 
       if (pos != ListView.INVALID_POSITION) { 
        Planet p = planetList.get(pos); 
        p.setSelected(isChecked); 


      /*Toast.makeText(
       getActivity(), 
       "Clicked on Pizza: " + p.getName() + ". State: is " 
         + isChecked, Toast.LENGTH_SHORT).show();*/ 
       } 


      } 
     }; 
     lv.setAdapter(plAdapter); 
    } 
    @Override 
    public void onPause() { 

     //get the instance variables 
     SharedPreferences preferences = getContext().getSharedPreferences("MaterialTabs", android.content.Context.MODE_PRIVATE); 
     boolean mCheckBoxValue = preferences.getBoolean("CheckBox_Value", false); 

     if (mCheckBoxValue) { 
      holder.chkBox.setChecked(true); 


     } else { 
      holder.chkBox.setChecked(false); 



     } 
     super.onPause(); 
    } 




    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 

     /*int pos = lv.getPositionForView(buttonView); 
     if (pos != ListView.INVALID_POSITION) { 
      Planet p = planetList.get(pos); 
      p.setSelected(isChecked); 


      *//*Toast.makeText(
       getActivity(), 
       "Clicked on Planet: " + p.getName() + ". State: is " 
         + isChecked, Toast.LENGTH_SHORT).show();*//* 
     }*/ 

    } 


    public void showResult(View v) { 
     String result2 = "Selected Product are :"; 
     int totalAmount2=0; 

     String a=""; 
     for (Birra b : biAdapter.getBox()){ 

      if (b.selected){ 

       result2 += "\n" + b.name+" "+b.distance+"€"+"q.tà :"+b.getQuantità(); 
       int quantitaInt= Integer.parseInt(b.getQuantità()); 
       totalAmount2+=b.distance * quantitaInt; 
       //a=String.valueOf(totalAmount); 


      } 
     } 
    /* for (Planet p : plAdapter.getBox()) { 
      if (p.selected){ 

       result += "\n" + p.name+" "+p.distance+"€"+"q.tà :"+p.getQuantità(); 
       int quantitaInt= Integer.parseInt(p.getQuantità()); 
       totalAmount+=p.distance * quantitaInt; 
       //a=String.valueOf(totalAmount); 


      } 
     }*/ 
     //Toast.makeText(getActivity(), result + "\n" + "Total Amount:=" + totalAmount + "€", Toast.LENGTH_LONG).show(); 
     Toast.makeText(getActivity(), result2 + "\n" + "Total Amount:=" + totalAmount2 + "€", Toast.LENGTH_LONG).show(); 

     /*Bundle bun2 = new Bundle(); 
     bun2.putString("scelta", result); 
     TwoFragment fgsearch2 = new TwoFragment(); 
     fgsearch2.setArguments(bun2); 
     android.support.v4.app.FragmentTransaction transaction2 = getActivity().getSupportFragmentManager().beginTransaction(); 
     transaction2.replace(R.id.content_main, fgsearch2); 
     transaction2.commit(); 


     Bundle bun = new Bundle(); 
     bun.putString("totale", a); 
     TwoFragment fgsearch = new TwoFragment(); 
     fgsearch.setArguments(bun); 
     android.support.v4.app.FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction(); 
     transaction.replace(R.id.content_main2, fgsearch); 
     transaction.commit(); 
*/ 













    } 




} 

Answer 1

@Override 
public void afterTextChanged(Editable s) { 
         p.setQuantità(finalHolder.edit.getText().toString().trim()); 
         SharedPreferences preferences = getContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE); 
         SharedPreferences.Editor editor = preferences.edit(); 
         editor.putString("KEY", finalHolder.edit.getText().toString().trim()); 
         editor.putBoolean("CheckBox_Value", finalHolder.chkBox.isChecked()); 
         editor.commit(); 

} 

、あなたはすでにあなたの中に `holder`は何

Answer 2

@Override 

    protected void onCreate(Bundle savedInstanceState) { 

     // TODO Auto-generated method stub 

     super.onCreate(savedInstanceState); 

     setContentView(R.layout.main); 



     checkBox = (CheckBox) findViewById(R.id.checkBox1);       
     SavedPreferences(); 

    } 


    private void savePreferences(boolean value) { 

     SharedPreferences sharedPreferences = PreferenceManager 

       .getDefaultSharedPreferences(this); 

     Editor editor = sharedPreferences.edit(); 

     editor.putBoolean(value); 

     editor.commit(); 

    } 





public class activity2 extends fragment{ 

     public onCreateView extends Fragment { 
     SharedPreferences sharedPreferences = PreferenceManager 

       .getDefaultSharedPreferences(this); 

     boolean checkBoxValue = sharedPreferences.getBoolean("CheckBox_Value", false);  

     if (checkBoxValue) { 

      checkBox.setChecked(true); 

     } else { 

      checkBox.setChecked(false); 

     } 


    } 



    }