SharedPreferences — 读得不好但写得好

Question

我有一个带有ListView 的应用程序，其中包含照片、文本字段和CheckBox。我想保存CheckBox 的状态。我将setOnCheckedChangeListener() 分配给CheckBox。当我点击复选框时一切正常，我在保存日志后阅读了属性。

当我打开应用程序并选择一个或多个复选框并单击“返回”按钮退出时，会出现此问题。当我打开应用程序时，复选框是错误的，如果我关闭并再次打开会发生。为了保存，我有一个唯一的变量 ID。

你能帮忙吗？

• ItemListBaseAdapter:

  public class ItemListBaseAdapter extends BaseAdapter {
  
      private static ArrayList<ItemDetails> itemDetailsrrayList;
  
      private Integer[] imgid = { R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5,
              R.drawable.img6 };
  
      private LayoutInflater l_Inflater;
      private Context _context;
  
      private SharedPreferences _apref;
      private Editor _editor;
      private String _NOMBREPREF = "perroo";
      private String _CADINICIO = "gatoo";
  
      public ItemListBaseAdapter(Context context, ArrayList<ItemDetails> results) {
          _context = context;
          itemDetailsrrayList = results;
          l_Inflater = LayoutInflater.from(context);
  
          _apref = _context.getSharedPreferences(_NOMBREPREF, Context.MODE_PRIVATE);
          _editor = _apref.edit();
      }
  
      public int getCount() {
          return itemDetailsrrayList.size();
      }
  
      public Object getItem(int position) {
          return itemDetailsrrayList.get(position);
      }
  
      public long getItemId(int position) {
          return position;
      }
  
      public View getView(final int position, View convertView, ViewGroup parent) {
          ViewHolder holder;
          if (convertView == null) {
              convertView = l_Inflater.inflate(R.layout.item_details_view, null);
              holder = new ViewHolder();
              holder.txt_itemName = (TextView) convertView.findViewById(R.id.name);
              holder.txt_itemDescription = (TextView) convertView.findViewById(R.id.itemDescription);
              holder.txt_itemPrice = (TextView) convertView.findViewById(R.id.price);
              holder.itemImage = (ImageView) convertView.findViewById(R.id.photo);
              holder.ckb_degustado = (CheckBox) convertView.findViewById(R.id.checkBox1);
  
              convertView.setTag(holder);
          } else {
              holder = (ViewHolder) convertView.getTag();
          }
  
          holder.txt_itemName.setText(itemDetailsrrayList.get(position).getName());
  
          holder.txt_itemDescription.setText(itemDetailsrrayList.get(position).getItemDescription());
          holder.txt_itemPrice.setText(itemDetailsrrayList.get(position).getPrice());
  
          holder.itemImage.setImageResource(imgid[itemDetailsrrayList.get(position).getImageNumber() - 1]);
  
          boolean tmprf = readPrefsCheckbox(itemDetailsrrayList.get(position).getIduniko().toString());
          String tmpr2 = Boolean.toString(tmprf);
          holder.ckb_degustado.setChecked(tmprf);
          Log.d("DREKION", "Inicio: " + itemDetailsrrayList.get(position).getIduniko().toString() + " " + tmpr2);
  
          // Checkbox degustation clickado
          holder.ckb_degustado.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
  
              @Override
              public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                  // TODO Auto-generated method stub
                  String cad1;
                  boolean cadtmp;
                  String cadtmpp;
  
                  if (isChecked == true) {
                      cad1 = _CADINICIO + itemDetailsrrayList.get(position).getIduniko().toString();
                      Log.d("DREKION", "True: " + cad1);
                      _editor.putBoolean(cad1, true);
                      _editor.commit();
                      cadtmp = readPrefsCheckbox(itemDetailsrrayList.get(position).getIduniko().toString());
                      cadtmpp = Boolean.toString(cadtmp);
                      Log.d("DREKION", "True despues: " + cadtmpp);
                  } else {
                      cad1 = _CADINICIO + itemDetailsrrayList.get(position).getIduniko().toString();
                      Log.d("DREKION", "False: " + cad1);
                      _editor.putBoolean(cad1, false);
                      _editor.commit();
                      cadtmp = readPrefsCheckbox(itemDetailsrrayList.get(position).getIduniko().toString());
                      cadtmpp = Boolean.toString(cadtmp);
                      Log.d("DREKION", "False despues: " + cadtmpp);
                  }
              }
          });
  
          convertView.setOnClickListener(new OnClickListener() {
  
              @Override
              public void onClick(View v) {
                  // do something here
                  // for communication with Fragment/Activity, you can use your
                  // own listener
                  /*
                   * Toast.makeText(v.getContext(), "Has elegido : " +
                   * itemDetailsrrayList.get(position).getItemDescription() + "",
                   * Toast.LENGTH_LONG).show(); Intent intent = new
                   * Intent(v.getContext(), ItemMoreInfo.class);
                   * intent.putExtra("objetito",
                   * itemDetailsrrayList.get(position));
                   */
                  sendMessage(v, itemDetailsrrayList.get(position));
              }
          });
          return convertView;
      }
  
      private boolean readPrefsCheckbox(String _iduniko) {
  
          return _apref.getBoolean(_CADINICIO + _iduniko, false);
      }
  
      public void sendMessage(View view, ItemDetails objID) {
          Intent intent = new Intent(view.getContext(), ItemMoreInfo.class);
          intent.putExtra("objetito", objID);
          view.getContext().startActivity(intent);
      }
  
      private void showNotificacion(Context c, String t) {
          Toast.makeText(c, t, Toast.LENGTH_LONG).show();
      }
  
      static class ViewHolder {
  
          TextView txt_itemName;
          TextView txt_itemDescription;
          TextView txt_itemPrice;
          ImageView itemImage;
          CheckBox ckb_degustado;
      }
  }
  

• MainActivity:

  public class MainActivity extends Activity {
  
      private SharedPreferences pref;
      private Editor editor;
  
      private String _NOMBREPREF = "perroo";
      private String _CADINICIO = "gatoo";
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          ArrayList<ItemDetails> image_details = GetSearchResults();
  
          // Init shares vars
          pref = getApplicationContext().getSharedPreferences(_NOMBREPREF, 0);
          editor = pref.edit();
  
          final ListView lv1 = (ListView) findViewById(R.id.listV_main);
          lv1.setAdapter(new ItemListBaseAdapter(this, image_details));
          //
          lv1.setOnItemClickListener(new OnItemClickListener() {
  
              @Override
              public void onItemClick(AdapterView<?> a, View v, int position, long id) {
                  /*
                   * 
                   * Object o = lv1.getItemAtPosition(position); ItemDetails
                   * obj_itemDetails = (ItemDetails)o;
                   * Toast.makeText(MainActivity.this, "Has elegido : " + " " +
                   * obj_itemDetails.getName(), Toast.LENGTH_LONG).show();
                   * sendMessage
                   * (findViewById(android.R.id.content),obj_itemDetails);
                   */
              }
          });
      }
  
      private ArrayList<ItemDetails> GetSearchResults() {
          ArrayList<ItemDetails> results = new ArrayList<ItemDetails>();
  
          ItemDetails item_details = new ItemDetails();
          item_details.setIduniko("tap001");
          item_details.setName("Pizza");
          item_details.setItemDescription("prueba");
          item_details.setPrice("2€");
          item_details.setImageNumber(1);
          results.add(item_details);
      }
  }
  

Answer 1

position 在 onCheckedChanged() 方法中的值与循环中 position 的值不同，因为代码在不同的时间运行...每次滚动 ListView 时都会运行循环，而 @ 987654324@ 在用户单击 CheckBox 时运行。

一个简单的解决方法是使用setTag() 和getTag() 来存储该行的字符串。
循环内部：

holder.ckb_degustado.setTag(itemDetailsrrayList.get(position).getIduniko());

内部onCheckedChanged()：

cad1 = _CADINICIO + ((String) buttonView.getTag());

（还可以考虑存储对itemDetailsrrayList.get(position) 的本地引用，而不是重复调用相同的方法。）