为什么EditText中的输入值在RecyclerView中滚动时交换其位置？

时间：2015-09-10 05:40:33

标签： android android-edittext android-recyclerview android-viewholder

在EditText中输入输入后，如果向上或向下滚动非常快，输入值会在RecyclerView中的另一个EditText中交换其位置。
在滚动之前，数据位于第一个EditText中 在向上和向下滚动之后，第一个EditText的值将其位置更改为第4个，并且交换是随机的。是否有任何工作来稳定数据。

Here is a sample screenshot

这是模型类：

public class Product {    
    public int pId;    
    public String pName;    
    public double unit_price;    
    public double discount;    
}

这是适配器类：

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductListHolder> {
Context context;
List<Product> productList;

public ProductAdapter(Context c, List<Product> lp){
    this.context = c;
    this.productList = lp;
}

public class ProductListHolder extends RecyclerView.ViewHolder{
    TextView tvName;
    TextView tvPrice;
    TextView tvDiscount;
    TextView tvTotal;
    EditText etQuantity;
    public ProductListHolder(View itemView) {
        super(itemView);
        tvName = (TextView) itemView.findViewById(R.id.tvName);
        tvPrice = (TextView) itemView.findViewById(R.id.tvPrice);
        tvDiscount = (TextView) itemView.findViewById(R.id.tvDiscount);
        tvTotal = (TextView) itemView.findViewById(R.id.tvTotal);
        etQuantity = (EditText) itemView.findViewById(R.id.etQuantity);
    }
}

@Override
public ProductListHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.single_row, viewGroup, false);
    ProductListHolder ph = new ProductListHolder(v);
    return  ph;
}

@Override
public void onBindViewHolder(final ProductListHolder productListHolder, final int i) {
    productListHolder.tvName.setText(productList.get(i).pName);
    productListHolder.tvPrice.setText(String.valueOf(productList.get(i).unit_price));
    productListHolder.tvDiscount.setText(String.valueOf(productList.get(i).discount));

    productListHolder.etQuantity.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) {
            if (!s.toString().equals("")){
                double totalPrice = (productList.get(i).unit_price-productList.get(i).discount)* (Double.valueOf(s.toString()));
                productListHolder.tvTotal.setText(String.valueOf(totalPrice));
            }
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });
}

@Override
public int getItemCount() {
    return productList.size();
}

}

以下是MainActivity：

public class MainActivity extends AppCompatActivity {

List<Product> productList;
RecyclerView recyclerView;
RecyclerView.Adapter mAdapter;

String[] names = {"A", "B", "C","D"};
double[] prices = {1000, 2000, 3000, 100};
double[] discounts = {10, 20, 30, 2};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initRecyclerView(); // Initializing Recycler View
    new MyTask().execute();
}

public void initRecyclerView(){
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this));
}

private class MyTask extends AsyncTask<Void, Void, List<Product>> {

    @Override
    protected List<Product> doInBackground(Void... params) {
        int sz = 24;
        productList = new ArrayList<Product>();
        for(int i=0; i<sz; i++){
            Product p = new Product();
            p.pId = i%4;
            p.pName = names[i%4];
            p.unit_price = prices[i%4];
            p.discount = discounts[i%4];
            productList.add(p);
        }

        return productList;
    }

    @Override
    protected void onPostExecute(List<Product> products) {
        super.onPostExecute(products);
        mAdapter = new ProductAdapter(MainActivity.this, productList);
        recyclerView.setAdapter(mAdapter);
    }
  }    
}

4 个答案:

答案 0 :(得分：13)

我认为你做得很好。但是你解决的问题可以通过一种非常简单的方式解决。您只需要实现重写方法：

  

public int getItemViewType（int position）{           return super.getItemViewType（position）;       }

取代 -

  

返回super.getItemViewType（position）;

回归 -

  

返回位置;

我认为您的所有问题都将以简单的方式解决。这是我修改过的适配器类：

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductListHolder> {

Context context;
List<Product> productList;


public ProductAdapter(Context c, List<Product> lp) {
    this.context = c;
    this.productList = lp;
}

public class ProductListHolder extends RecyclerView.ViewHolder {
    TextView tvName;
    TextView tvPrice;
    TextView tvDiscount;
    TextView tvTotal;
    EditText etQuantity;

    public ProductListHolder(View itemView) {
        super(itemView);
        tvName = (TextView) itemView.findViewById(R.id.tvName);
        tvPrice = (TextView) itemView.findViewById(R.id.tvPrice);
        tvDiscount = (TextView) itemView.findViewById(R.id.tvDiscount);
        tvTotal = (TextView) itemView.findViewById(R.id.tvTotal);
        etQuantity = (EditText) itemView.findViewById(R.id.etQuantity);
    }
}

@Override
public ProductListHolder onCreateViewHolder(ViewGroup viewGroup, final int i) {
    View v = LayoutInflater.from(context).inflate(R.layout.single_row, viewGroup, false);
    ProductListHolder ph = new ProductListHolder(v);
    return ph;
}

@Override
public void onBindViewHolder(final ProductListHolder productListHolder, final int i) {

    productListHolder.tvName.setText(productList.get(i).pName);
    productListHolder.tvPrice.setText(String.valueOf(productList.get(i).unit_price));
    productListHolder.tvDiscount.setText(String.valueOf(productList.get(i).discount));

    productListHolder.etQuantity.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) {
            productListHolder.tvTotal.setText(s.toString());
        }

        @Override
        public void afterTextChanged(Editable s) {
        }
    });

}

@Override
public int getItemCount() {
    return productList.size();
}

@Override
public int getItemViewType(int position) {
    return position;
}    
}

答案 1 :(得分：5)

你正在调用etQuantity.addTextChangedListener，但你永远不会删除监听器，所以当视图持有者被回收（也就是用于显示另一个项目）时，它会添加另一个文本更改的监听器（所以它将有两个不同的文本更改的侦听器注册。）

最简单的解决方法可能只需在addTextChangedListener中拨打onCreateViewHolder一次，然后使用getAdapterPosition代替i来获取该位置。

答案 2 :(得分：5)

我已经解决了这个问题。

问题是我在 onBindViewHolder 中添加了 addTextChangedListener 。所以EditText中的值总是混乱，因为当焦点移动另一个 addTextChangedListener 被注册时。所以我做的是，我实现了另一个名为 CustomEtListener 的自定义类，并实现了 TextWatcher 。所以现在我在 onCreateViewHolder 中为每个EditText注册了自定义监听器。并使用数组字符串来存储编辑文本的值。并且数组的大小是RecyclerView中的项目数。并且方法 updatePosition 用于获取焦点项的位置。然后 onTextChanged 我只是将editText的值存储在数组中，并在 onBindViewHolder 中更新了EditText的值。之后我每次滚动时，EditText的值都不会改变。

这是我的适配器类。

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductListHolder> {
Context context;
List<Product> productList;
String[] etValArr;
double[] totalValue;

public ProductAdapter(Context c, List<Product> lp) {
    this.context = c;
    this.productList = lp;
    // Create a new array which size matches the number of Edit Texts
    etValArr = new String[productList.size()];
    // and an array for holding all the values of each edit text
    totalValue = new double[productList.size()];
}

public class ProductListHolder extends RecyclerView.ViewHolder {
    TextView tvName;
    TextView tvPrice;
    TextView tvDiscount;
    TextView tvTotal;
    EditText etQuantity;

    // Instance of a Custom edit text listener
    public CustomEtListener myCustomEditTextListener;

    public ProductListHolder(View itemView, CustomEtListener myLis) {
        super(itemView);
        tvName = (TextView) itemView.findViewById(R.id.tvName);
        tvPrice = (TextView) itemView.findViewById(R.id.tvPrice);
        tvDiscount = (TextView) itemView.findViewById(R.id.tvDiscount);
        tvTotal = (TextView) itemView.findViewById(R.id.tvTotal);
        etQuantity = (EditText) itemView.findViewById(R.id.etQuantity);
        // assign a new instance of addTextChangedListener for each item
        myCustomEditTextListener = myLis;
        etQuantity.addTextChangedListener(myCustomEditTextListener);
    }
}

@Override
public ProductListHolder onCreateViewHolder(ViewGroup viewGroup, final int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.single_row, viewGroup, false);
    ProductListHolder ph = new ProductListHolder(v, new CustomEtListener());
    return ph;
}

@Override
public void onBindViewHolder(final ProductListHolder productListHolder, int i) {
    productListHolder.tvName.setText(productList.get(i).pName);
    productListHolder.tvPrice.setText(String.valueOf(productList.get(i).unit_price));
    productListHolder.tvDiscount.setText(String.valueOf(productList.get(i).discount));

    // Update the position when focus changes
    productListHolder.myCustomEditTextListener.updatePosition(i);
    // Setting the values accordingly
    productListHolder.etQuantity.setText(etValArr[i]);
    productListHolder.tvTotal.setText(String.valueOf(totalValue[i]));

}

@Override
public int getItemCount() {
    return productList.size();
}

/**
 * Custom class which implements Text Watcher
 */
private class CustomEtListener implements TextWatcher {
    private int position;

    /**
     * Updates the position according to onBindViewHolder
     *
     * @param position - position of the focused item
     */
    public void updatePosition(int position) {
        this.position = position;
    }

    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {
    }

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
        // Change the value of array according to the position
        etValArr[position] = charSequence.toString();
        // Doing the calculation
        if (!etValArr[position].equals("")) {
            totalValue[position] = (productList.get(position).unit_price - productList.get(position).discount) * (Double.valueOf(etValArr[position]));

        } else {
            totalValue[position] = 0.00;
        }
    }

    @Override
    public void afterTextChanged(Editable editable) {
    }
}
}

我还有问题。我无法更新Total列的值。我向上和向下滚动后，值改变了。所以我必须实现一个调用backListener来立即获取Total列的值。我现在有一个接口 TextCallBackListener ，并在Adapters ProductListHoldersClass上实现它。因此，每当调用 onTextChanged 时，它都会触发我的 updateText 方法来更改行Total的值。如果您不理解该视图，则问题中会有截图。

这是接口TextCallBackListener。

public interface TextCallBackListener {
      public void updateText(String val);
}

这是我更改的适配器类。

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductListHolder> {
Context context;
List<Product> productList;
String[] etValArr;
double[] totalValue;

public ProductAdapter(Context c, List<Product> lp) {
    this.context = c;
    this.productList = lp;
    // Create a new array which size matches the number of Edit Texts
    etValArr = new String[productList.size()];
    // and an array for holding all the values of each edit text
    totalValue = new double[productList.size()];
}


public class ProductListHolder extends RecyclerView.ViewHolder implements TextCallBackListener {
    TextView tvName;
    TextView tvPrice;
    TextView tvDiscount;
    TextView tvTotal;
    EditText etQuantity;

    // Instance of a Custom edit text listener
    public CustomEtListener myCustomEditTextListener;

    public ProductListHolder(View itemView, CustomEtListener myLis) {
        super(itemView);
        tvName = (TextView) itemView.findViewById(R.id.tvName);
        tvPrice = (TextView) itemView.findViewById(R.id.tvPrice);
        tvDiscount = (TextView) itemView.findViewById(R.id.tvDiscount);
        tvTotal = (TextView) itemView.findViewById(R.id.tvTotal);
        etQuantity = (EditText) itemView.findViewById(R.id.etQuantity);
        // assign a new instance of addTextChangedListener for each item
        myCustomEditTextListener = myLis;
        etQuantity.addTextChangedListener(myCustomEditTextListener);
    }

    @Override
    public void updateText(String val) {
        tvTotal.setText(val);
    }
}


@Override
public ProductListHolder onCreateViewHolder(ViewGroup viewGroup, final int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.single_row, viewGroup, false);
    ProductListHolder ph = new ProductListHolder(v, new CustomEtListener());
    return ph;
}

@Override
public void onBindViewHolder(final ProductListHolder productListHolder, int i) {
    productListHolder.tvName.setText(productList.get(i).pName);
    productListHolder.tvPrice.setText(String.valueOf(productList.get(i).unit_price));
    productListHolder.tvDiscount.setText(String.valueOf(productList.get(i).discount));

    // Update the position when focus changes
    productListHolder.myCustomEditTextListener.updatePosition(i, productListHolder);
    // Setting the values accordingly
    productListHolder.etQuantity.setText(etValArr[i]);
    //productListHolder.tvTotal.setText(String.valueOf(totalValue[i]));

}


@Override
public int getItemCount() {
    return productList.size();
}

/**
 * Custom class which implements Text Watcher
 */
private class CustomEtListener implements TextWatcher {
    private int position;
    TextCallBackListener textCallBackListener;

    /**
     * Updates the position according to onBindViewHolder
     *
     * @param position - position of the focused item
     * @param pa       - object of ProductListHolder Class
     */
    public void updatePosition(int position, ProductListHolder pa) {
        this.position = position;
        // assigning it to the instance of the CallBackListener
        textCallBackListener = (TextCallBackListener) pa;
    }

    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {
    }

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
        // Change the value of array according to the position
        etValArr[position] = charSequence.toString();
        // Doing the calculation
        if (!etValArr[position].equals("")) {
            totalValue[position] = (productList.get(position).unit_price - productList.get(position).discount) * (Double.valueOf(etValArr[position]));
            // triggering the callback function to update the total
            textCallBackListener.updateText(String.valueOf(totalValue[position]));
        } else {
            totalValue[position] = 0.00;
            textCallBackListener.updateText("0.00");
        }
    }

    @Override
    public void afterTextChanged(Editable editable) {

    }

}
}

答案 3 :(得分：0)

简单修复：

将 mFieldAdapter.notifyDataSetChanged();替换为：

for (int i = 0; i < mFieldAdapter.getItemCount(); i++) {
    // update each item itself
    mFieldAdapter.notifyItemChanged(i, fields.get(i));
}

演示：https://youtu.be/4JpzuLggBV0

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