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

Question

在EditText中输入输入后,如果向上或向下滚动非常快,则输入值会在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.

这是一个示例截图

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();
}

}

这是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);
    }
  }    
}

Answer 1

我觉得你做得很好.但是你解决的问题可以通过一种非常简单的方式解决.您只需要实现一个重写方法:

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

取代─

return super.getItemViewType(position);

刚回来 -

返回位置;

我认为你的所有问题都将以一种简单的方式解决.这是你修改了一下的适配器类:

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;
}    
}

Answer 2

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,导致焦点移动时另一个addTextChangedListener被注册.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.并使用一个字符串数组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我只是存储在数组中的EDITTEXT的值,并且更新在的EditText的值onBindViewHolder.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) {

    }

}
}

Answer 3

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,它将添加另一个文本更改的监听器(因此它将改变两个不同的文本)听众注册).

最简单的修复可能是只调用addTextChangedListener一次onCreateViewHolder并使用getAdapterPosition而不是i获取位置.