如何在按钮单击上更改列表项中的textView

我想更改我的数量textview以反映特定项目的数量。 但是在单击add和sub按钮时，setText（）函数似乎不起作用。 这是我的适配器类

public class ItemAdapter extends ArrayAdapter{ Context context; int[] images,rate,quant; String[] names; ImageButton add, sub; ViewHolder holder; // Since will be accessed inside onclick Integer count1=0; HashMap positiveNumbers = new HashMap(); Integer count=0; static class ViewHolder { public TextView textView; public ImageView imageView; public TextView number; public TextView rates; public String uniqueKey; } public ItemAdapter(Context c, String[] items, int quantity[], int[] rate, int[] img) { // TODO Auto-generated constructor stub super(c, R.layout.item_fooditems, R.id.tvitemname, items); this.context = c; this.images = img; this.names = items; this.rate=rate; this.quant=quantity; } @Override public View getView(final int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub View row = convertView; // reuse views if (row == null) { LayoutInflater inflater = (LayoutInflater) context .getSystemService(Context.LAYOUT_INFLATER_SERVICE); row = inflater.inflate(R.layout.item_fooditems, parent, false); ViewHolder viewHolder = new ViewHolder(); viewHolder.imageView = (ImageView) row.findViewById(R.id.ivimage); viewHolder.textView = (TextView) row.findViewById(R.id.tvitemname); viewHolder.number = (TextView)row.findViewById(R.id.tvquantity); viewHolder.rates = (TextView)row.findViewById(R.id.tvprice); viewHolder.uniqueKey = String.valueOf(position); add = (ImageButton) row.findViewById(R.id.bincrement); add.setTag(position); sub = (ImageButton) row.findViewById(R.id.bdecrement); sub.setTag(position); row.setTag(viewHolder); } holder = (ViewHolder) row.getTag(); //keeping one global memory holder.imageView.setImageResource(images[position]); holder.textView.setText(names[position]); holder.rates.setText(Integer.toString(rate[position])); holder.number.setText(Integer.toString(quant[position])); holder.number.setText("x"); add.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub quant[position]=quant[position]+1; count1 +=1; //holder.number.setText(Integer.toString(quant[position])); holder.number.setText(count1.toString()); Toast.makeText(context, Integer.toString(quant[position]), Toast.LENGTH_SHORT).show(); Log.d("Quantity",Integer.toString(quant[position])); positiveNumbers.put(holder.uniqueKey,count); //Key -> String.valueOf(position) and Value -> int count } }); sub.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub quant[position]--; Toast.makeText(context, Integer.toString(quant[position]), Toast.LENGTH_SHORT).show(); holder.number.setText(Integer.toString(quant[position])); positiveNumbers.put(holder.uniqueKey,count); //Key -> String.valueOf(position) and Value -> int count } }); return row; } public HashMap getPositiveNumbers() { return positiveNumbers; } } 

需要进行哪些修改？

Answer 1

首先，您应该使用所需的所有值创建一个自定义模态类，而不是采用这些单独的数组。 例如，在您的情况下，它将是这样的。

  public class Item { private String itemName = ""; private int quantity; private int rate; private int image; public String getItemName() { return itemName; } public void setItemName(String itemName) { this.itemName = itemName; } public int getQuantity() { return quantity; } public void setQuantity(int quantity) { this.quantity = quantity; } public int getRate() { return rate; } public void setRate(int rate) { this.rate = rate; } public int getImage() { return image; } public void setImage(int image) { this.image = image; } } 

现在将这个模态类传递给你的适配器构造函数。这就是你在getView（）中设置值的方法

  Item item=itemList.get(position); //here itemList is the list you are passing to your adapter. holder.imageView.setImageResource(item.getImage()); holder.textView.setText(item.getItemName()); holder.rates.setText(String.valueOf(item.getRate())); holder.number.setText(String.valueOf(item.getQuantity())); 

现在进入您的添加/子单击侦听器，无需在添加/子单击侦听器中设置数量TextView的文本。 您可以在更新itemList的相应索引处的数量值后通知您的适配器。 例如。 为了增加数量，你可以做这样的事情。

 add.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Item item=itemList.get(position);// getting the item at particular position item.setQuantity(item.getQuantity()+1);// incrementing item quantity by 1 itemList.set(position,item);// updating the itemList to that new item with incremented quantity notifyDataSetChanged();//notifying the adapter } }); 

您可以为减去数量onClickListener（）做同样的事情。

 sub.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Item item=itemList.get(position);//getting the item at particular position item.setQuantity(item.getQuantity()-1);//decrementing item quantity by 1 itemList.set(position,item);// updating the itemList to that new item with decremented quantity notifyDataSetChanged();//notifying the adapter } }); 

这肯定会奏效。 在处理ListView / RecyclerView的自定义适配器时，最好还是维护单个列表而不是多个数组。

Answer 2

你必须只调用notifyDataSetChanged（）; 添加和子按钮单击代码后。

添加

 add.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub quant[position]=quant[position]+1; count1 +=1; //holder.number.setText(Integer.toString(quant[position])); holder.number.setText(count1.toString()); Toast.makeText(context, Integer.toString(quant[position]), Toast.LENGTH_SHORT).show(); Log.d("Quantity",Integer.toString(quant[position])); positiveNumbers.put(holder.uniqueKey,count); //Key -> String.valueOf(position) and Value -> int count notifyDataSetChanged(); } }); 

对于Sub

 sub.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub quant[position]--; Toast.makeText(context, Integer.toString(quant[position]), Toast.LENGTH_SHORT).show(); holder.number.setText(Integer.toString(quant[position])); positiveNumbers.put(holder.uniqueKey,count); //Key -> String.valueOf(position) and Value -> int count notifyDataSetChanged(); } }); 

希望它的帮助!!