how can i save checkbox value with shared preferences?

I don't know why my code not save checkbox checked value; if I check checkbox and after I click on another tab and comeback to previous tab, checkbox is not selected...I hope that you find the error in my code!

IDE says to me: FATAL EXCEPTION: main java.lang.NullPointerException at line ".onCreateView(holder.chkBox.setChecked(true);"

Why?

ADAPTER CLASS:

public abstract class PlanetAdapter extends ArrayAdapter<Planet> implements CompoundButton.OnCheckedChangeListener{

    private List<Planet> planetList;
    private Context context;
    ArrayList<Birra> objects;


    public PlanetAdapter(List<Planet> planetList, Context context) {
        super(context, R.layout.single_listview_item, planetList);
        this.planetList = planetList;
        this.context = context;
    }


    public class PlanetHolder {
        public TextView planetName;
        public TextView distView;
        public TextView valuta;
        public CheckBox chkBox;
        public EditText edit;
        public String quantità;


    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {


        View row = convertView;
        PlanetHolder holder = null;
        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(R.layout.single_listview_item, parent, false);
            holder = new PlanetHolder();
            holder.planetName = (TextView) row.findViewById(R.id.name);
            holder.distView = (TextView) row.findViewById(R.id.dist);
            holder.valuta = (TextView) row.findViewById(R.id.valuta);
            holder.chkBox = (CheckBox) row.findViewById(R.id.chk_box);
            holder.edit = (EditText) row.findViewById(R.id.editText);
            holder.edit.setVisibility(View.GONE);
            holder.edit.setEnabled(false);
            row.setTag(holder);
        } else {
            holder = (PlanetHolder) row.getTag();
        }
        final Planet p = planetList.get(position);


        final PlanetHolder finalHolder = holder;

      /*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);
      }*/


        holder.chkBox.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (finalHolder.chkBox.isChecked()) {
                    finalHolder.edit.setVisibility(View.VISIBLE);
                    finalHolder.edit.setEnabled(true);
                    SharedPreferences preferences = getContext().getSharedPreferences("MaterialTabs", android.content.Context.MODE_PRIVATE);
                 /* SharedPreferences.Editor editor = preferences.edit();
                  editor.putBoolean("showActivity", finalHolder.chkBox.isChecked());
                  editor.commit();*/
                    // boolean value= true;
                    SharedPreferences.Editor mEditor = preferences.edit();
                    mEditor.putBoolean("CheckBox_Value", finalHolder.chkBox.isChecked());

                    mEditor.commit();

                    finalHolder.edit.addTextChangedListener(new TextWatcher() {
                        @Override
                        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                        }

                        @Override
                        public void onTextChanged(CharSequence s, int start, int before, int count) {
                        }

                        @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.commit();

                        }
                    });
                } else {
                    finalHolder.edit.setVisibility(View.GONE);
                    finalHolder.edit.setEnabled(false);
                    finalHolder.edit.setText(null);

                }

            }
        });
        holder.planetName.setText(p.getName());
        holder.distView.setText("" + p.getDistance());
        holder.valuta.setText("" + p.getValuta());
        holder.chkBox.setChecked(p.isSelected());
        holder.chkBox.setTag(p);
        holder.edit.setEnabled(false);

        return row;
    }


    ArrayList<Planet> getBox() {
        ArrayList<Planet> box = new ArrayList<Planet>();
        for (Planet p : planetList) {
            if (p.selected)
                box.add(p);
        }
        return box;
    }
}

FRAGMENT:

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


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);
    SharedPreferences preferences = getContext().getSharedPreferences("MaterialTabs", android.content.Context.MODE_PRIVATE);
    // preferences.getBoolean("showActivity", false);
    //preferences.getString("KEY", null);
    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;
}