Android的保存按钮的状态电网

Question

我有2个问题：

1）如何选择电网的特定按钮，因为我实现的方式，它总是选择的第一个按钮，即使我点击另一个按钮。

2nd）执行poiint“1”后，我想向用户显示可用的产品，它将以绿色背景色显示。如果用户点击按钮，backgroundcolor将变为红色。问题是，如果我改变活动，然后再回来，颜色将是默认的颜色，即绿色。我希望活动保存这些按钮的状态以便在用户离开时重新加载。

下面是代码：

public class ShowList extends AppCompatActivity { 

     ...(some methods that aren't relevant) 

    //Here i'm retrieving objects from a database table and adding them to a List which will add items to a Grid using GridViewAdapter (class shown below) 
    public void addItemsToGridListView(String tableName) { 

      productsGridView.clear(); 

      Cursor res = db.getFromSpecificTAble(tableName); 

      while(res.moveToNext()) { 

       String productName = res.getString(0); 
       String productPrice = res.getString(1); 
       String buyType = res.getString(2); 
       String productQuantity = res.getString(3); 
       Product p = new Product(productName, productPrice);p.setBuyType(buyType);p.setProductQuantity(productQuantity); 
       productsGridView.add(p); 
      } 

     adapter = new GridViewAdapter(this,productsGridView); 

     view = (GridView) findViewById(R.id.gridView2); 

     view.setAdapter(adapter); 

    } 

//这里是按钮事件改变的backgroundColor 公共无效goToBin（视图v）{

  Button b = (Button) findViewById(R.id.textViewList1); 

      b.setBackgroundColor(0xffff0000); 

      adapter.notifyDataSetChanged(); 
     } 
} 


public class GridViewAdapter extends BaseAdapter { 

    private ArrayList<Product> products; 
    private Context context; 
    private LayoutInflater inflater; 

    public GridViewAdapter(Context context, ArrayList<Product> products) { 

     this.products = products; 
     this.context = context; 
     inflater = LayoutInflater.from(this.context); } 

    @Override 
    public int getCount() { 
     return products.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     return products.get(position); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    private class ViewHolder { 
     Button productName; 
     TextView productPrice; 
     TextView buyType; 
     TextView productQuantity; 
     ImageButton removeProduct; 
    } 
    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder = null; 
     if (convertView == null || (convertView.getTag() == null)) { 
      convertView = inflater.inflate(R.layout.listview_values, parent, false); 
      holder = new ViewHolder(); 
      holder.productName = (Button) convertView.findViewById(R.id.textViewList1); 
      holder.productPrice = (TextView) convertView.findViewById(R.id.EditTextList2); 
      holder.buyType = (TextView) convertView.findViewById(R.id.textViewList3); 
      holder.productQuantity = (TextView) convertView.findViewById(R.id.textViewList4); 
      holder.removeProduct = (ImageButton) convertView.findViewById(R.id.removeProduct); 
     } 
     else { 
      holder = (ViewHolder) convertView.getTag(); 
     } 
     convertView.setTag(holder); 
     holder.productName.setText(products.get(position).getProductName()); 
     holder.productPrice.setText(String.valueOf(products.get(position).getProductPrice()) + " €"); 
     holder.buyType.setText(products.get(position).getBuyType()); 
     holder.productQuantity.setText(String.valueOf(products.get(position).getProductQuantity()) + " Un."); 
     holder.removeProduct.setTag(new Integer(position)); 

     return convertView; 
    } 
} 

当我开始活动它会是这样的：

当我点击按钮1：

但是，当我离开那个actitvity回来这一个按钮将是我以前改变了颜色都是绿色的，而不是保存的...红。

谢谢。

Answer 1

尝试这些： 1.修改ShowList.java

SharedPreferences pref_restore = this.getSharedPreferences("PREFERENCE", Context.MODE_PRIVATE); 
int position = pref_restore.getInt("position", -1); 

adapter = new GridViewAdapter(this, productsGridView, position); 

view = (GridView) findViewById(R.id.gridView2); 

view.setAdapter(adapter); 

view.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      GridViewAdapter adapter = new GridViewAdapter(ShowList.this, productsGridView, position); 
      view.setAdapter(adapter); 

      //Save position to SharedPreferences; 
      SharedPreferences pref_save = ShowList.this.getSharedPreferences("PREFERENCE", Context.MODE_PRIVATE); 
      SharedPreferences.Editor editor = pref_save.edit(); 
      editor.putInt("position", position); 
      editor.apply(); 
     } 
    }); 

修改GridViewAdapter.java

修改GridViewAdapter构造函数到

public GridViewAdapter(Context context, ArrayList<Product> products, int mSelectedPosition) 

和修饰身在getView方法是这样的：

holder.productName = (Button) convertView.findViewById(R.id.textViewList1); 
if(position == mSelectedPosition){ 
    holder.productName.setBackgroundColor(0xffff0000); 
} 

如果不能点击的项目尽量设置一些属性，以您的按钮包含在listview_values.xml：

<Button 
    android:id="@+id/textViewList1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:focusableInTouchMode="false" 
    android:clickable="false" 
    android:focusable="false"/>