ArrayList添加和刪除對象

Question

我正在開發一個android應用程序，我必須使用自定義listview和複選框。當用戶選中/取消選中時，我需要分別添加/刪除數組列表中的對象。

這裏是我的代碼：

@Override 
public void onItemClick(AdapterView<?> parent, View view, int position, long id) 
{ 
    selectedView=view; 
    System.out.println("Position of list item:"+position); 
    if(parent.getAdapter().equals(categoryAdapter)) 
    {  
     System.out.println("First Adapter");   
     fl=new FoodList();  
     System.out.println("Tag:"+view.getTag()); 
     btOrder.setVisibility(View.GONE); 
     addToOrder.setVisibility(View.VISIBLE); 
     back.setVisibility(View.VISIBLE); 
     buttonSeperator.setVisibility(View.VISIBLE); 


     fl.bundleCategory=fc.list[position];   
     fl.foodListService();  
     checks=new SparseBooleanArray();   
     quantity=new SparseArray<Integer>(); 

     orderList=new ArrayList<Order>(); 
     order=new Order(); 
     Order Null=null; 
     for(int i=0;i<fl.foodList.size();i++) 
     { 
      checks.put(i, false); 
      quantity.put(i, 0); 
      order.setQuantity(0); 
      order.setItem(""); 
      //orderList.add(i,Null); 
      //orderList.add(i,order); 
      orderList.add(order); 
      System.out.println("Adding at pos:"+i+"Value:"+Null); 
     } 
     WaiterFoodAdapter foodAdapter=new WaiterFoodAdapter(this, R.layout.take_order_list, fl.foodList); 
     categoryList.setAdapter(foodAdapter); 
     categoryList.setOnItemClickListener(this); 
     } 
     else 
     {   
      System.out.println("Second Adapter:Id="+parent.getId()); 

      if(view != null) 
      { 
       final TextView tvItem=(TextView)selectedView.findViewById(R.id.foodName); 
       final TextView tvQuantity=(TextView)selectedView.findViewById(R.id.quantity); 

       selectedPosition=position; 
       SelectFood = (CheckBox)view.findViewById(R.id.selectFood); 

       if(SelectFood.isChecked())   
       {   
        SelectFood.setChecked(false);     
        checks.put(selectedPosition, false); 
        quantity.put(selectedPosition,0); 

        //order.setQuantity(0); 
        //order.setItem(""); 
        System.out.println("Removing at pos:"+selectedPosition+"Value:"+orderList.get(selectedPosition).getItem()+orderList.get(selectedPosition).getQuantity()); 
        orderList.remove(orderList.get(selectedPosition)); 

        tvQuantity.setText("0"); 
        System.out.println("Position="+selectedPosition); 
       }   
       else 
       { 
        SelectFood.setChecked(true);      
        checks.put(selectedPosition, true); 
        System.out.println("Position="+selectedPosition); 

        //orderList=new ArrayList<Order>();      
        final AlertDialog.Builder quantityAlert= new AlertDialog.Builder(TakeOrder.this); 
        quantityAlert.setTitle("Quantity"); 
        quantityAlert.setMessage("Please enter quantity"); 

        final EditText input = new EditText(TakeOrder.this); 
        input.setInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL); 
        quantityAlert.setView(input); 

        quantityAlert.setPositiveButton("Ok", new DialogInterface.OnClickListener() 
        { 
         public void onClick(DialogInterface dialog, int whichButton) 
         { 
          value = input.getText(); 



          if(value.toString().equals("")) 
          {    
           SelectFood.setChecked(false); 
           Toast msg=Toast.makeText(TakeOrder.this, "Please provide quantity", Toast.LENGTH_SHORT); 
           msg.show();  
          } 
          else 
           if(value.toString().equals("0")) 
           {      
            SelectFood.setChecked(false);       
            Toast msg=Toast.makeText(TakeOrder.this, "Please enter valid quantity", Toast.LENGTH_SHORT);       
            msg.show(); 
           } 
           else      
           {         
            tvQuantity.setText(value); 
            quantity.put(selectedPosition, Integer.valueOf(value.toString())); 
            order.setQuantity(Integer.valueOf(tvQuantity.getText().toString())); 
            order.setItem(tvItem.getText().toString()); 
            orderList.add(selectedPosition, order); 
            System.out.println("setting at pos:"+selectedPosition+"Value:"+orderList.get(selectedPosition).getItem()+orderList.get(selectedPosition).getQuantity()); 
           } 



          //Log.v("Item:",orderList.get(selectedPosition).getItem()); 
          //Log.v("Quantity:",String.valueOf(orderList.get(selectedPosition).getQuantity())); 

         }    
        }); 

       quantityAlert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() 
       { 
         public void onClick(DialogInterface dialog, int whichButton) 
         { 
          SelectFood.setChecked(false);     
         } 
        }); 

       quantityAlert.show(); 
      }           
     } 

    } 

} 

當用戶點擊按鈕addToOrder它只是搜索選中的複選框和剛開檢查listItems中的相關textViews值..

public void addToOrder(View v) 
{ 
    for(int i=0;i<fl.foodList.size();i++) 
    {   
     if(checks.get(i)==true) 
      { 
      System.out.println("Order is:"+orderList.get(i).getItem()+orderList.get(i).getQuantity()); 
      }     
    } 
} 

這是我的適配器，它是僅用於定製查看目的

public class WaiterFoodAdapter extends ArrayAdapter<Food> 
{ 
    Context context; 
    TakeOrder holder; 
    int layoutResourceId; 
    List<Food> foodList; 

    public WaiterFoodAdapter(Context context, int layoutResourceId,List<Food> foodList) 
    { 
     super(context, layoutResourceId, foodList);   
     this.context=context; 
     this.layoutResourceId=layoutResourceId; 
     this.foodList=foodList; 
    } 

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

     if(row==null) 
     { 
      LayoutInflater inflater=((Activity)context).getLayoutInflater(); 
      row=inflater.inflate(layoutResourceId, parent,false); 
      holder=new TakeOrder(); 
      holder.foodIcon=(ImageView)row.findViewById(R.id.foodIcon); 
      holder.tvFoodName=(TextView)row.findViewById(R.id.foodName); 
      holder.cbSelectFood=(CheckBox)row.findViewById(R.id.selectFood); 
      holder.cbSelectFood.setClickable(false);    
      holder.tvFoodDescription=(TextView)row.findViewById(R.id.foodDescription); 
      holder.tvFoodQuantity=(TextView)row.findViewById(R.id.foodQuantity); 
      holder.tvQuantity=(TextView)row.findViewById(R.id.quantity); 
      row.setTag(holder); 

     }  
     else 
     {    
      holder=(TakeOrder)row.getTag();    
     } 
     if(fl.bundleCategory.equals("Appetisers")) 
     { 
     holder.foodIcon.setImageResource(R.drawable.appetiser); 
     } 
     else 
      if(fl.bundleCategory.equals("Main Courses")) 
      { 
       holder.foodIcon.setImageResource(R.drawable.main_course); 
      } 
      else 
       if(fl.bundleCategory.equals("Sides")) 
       { 
        holder.foodIcon.setImageResource(R.drawable.sides); 
       } 
       else 
        if(fl.bundleCategory.equals("Desserts")) 
        { 
         holder.foodIcon.setImageResource(R.drawable.desserts); 
        } 
        else 
         if(fl.bundleCategory.equals("Drinks")) 
         { 
          holder.foodIcon.setImageResource(R.drawable.drinks); 
         } 
     holder.tvFoodName.setText(foodList.get(position).getMenuItem()); 
     holder.tvFoodDescription.setText(foodList.get(position).getDescription()); 
     holder.cbSelectFood.setChecked(checks.get(position)); 
     holder.tvQuantity.setText(String.valueOf(quantity.get(position)));  
     return row;  
    } 

} 

假設我選擇（檢查）兩個列出項目，然後按addToOrder按鈕，它只打印最後一次選擇的項目兩次。我不知道爲什麼它只是重寫我的名單中的第一個對象 我認爲我的邏輯是正確的，但不知道爲什麼它不工作？ 任何人都可以請幫助

Answer 1

你應該在你的適配器中創建一個方法，它可以讓你更新當前的數組列表或添加/刪除你傳遞的項目。但我看不出你如何實現你的適配器，這可能是最重要的代碼...

你需要這樣的事情，你的轉接器內（這是更新的完整列表）：

public void updateListArray(ArrayList<Item> list) { 
    this.clear(); 
    for(Item item : list) { 
     this.add(item); 
    } 
    notifyDataSetChanged(); 
}