异步删除ListView/RecyclerView项的最佳做法

Question

我有ListView一个CursorLoader.用户可以打开ListView项目(打开另一个Fragment项目)或删除项目.所有数据库操作都是异步发生的,通常只需要几分之一秒.但从技术上讲,用户可以删除一个项目,然后在删除回调和原因和错误之前打开该项目.处理这个问题的最佳方法是什么？以下是我看到的选项.

1. 假设AsyncTask总是会很快发生,以避免出现问题
2. 在UI线程上执行数据库操作
3. 使ListView之前无效AsyncTask(但这会导致UI中的闪存)
4. 在此期间以某种方式阻止用户输入 AsyncTask

编辑:我最终使用RecyclerView但adapter.notifyItemRemoved(itemPos)直到我从数据库中删除项目后才能调用.

Answer 1

您的案例中最好的选择是使用RecyclerView.因为当你点击删除时你可以打电话adapter.notifyItemRemoved(itemPos).因此,列表项将从您的动画中删除,RecyclerView您不必担心删除操作结果.

请参阅有关创建列表和卡片的Android开发人员教程:

RecyclerView当您拥有基于用户操作或网络事件在运行时更改其元素的数据集合时,请使用该窗口小部件.

这是一个例子:

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> implements View.OnClickListener, View.OnLongClickListener {

private ArrayList<String> mDataset;
private static Context sContext;

public MyAdapter(Context context, ArrayList<String> myDataset) {
    mDataset = myDataset;
    sContext = context;
}

@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.my_text_view, parent, false);

    ViewHolder holder = new ViewHolder(v);
    holder.mNameTextView.setOnClickListener(MyAdapter.this);

    holder.mNameTextView.setTag(holder);

    return holder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {

    holder.mNameTextView.setText(mDataset.get(position));

}

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


@Override
public void onClick(View view) {
    ViewHolder holder = (ViewHolder) view.getTag();
    if (view.getId() == holder.mNameTextView.getId()) {
        **//Important !!!**
        notifyItemRemoved(getPosition());
        // Make your database operation also here
    }
}



public static class ViewHolder extends RecyclerView.ViewHolder {
    public TextView mNumberRowTextView;
    public TextView mNameTextView;


    public ViewHolder(View v) {
        super(v);

        mNameTextView = (TextView) v.findViewById(R.id.nameTextView);
    }
}

Answer 2

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final View itemView = convertView != null ? convertView : /* inflate view */;
        itemView.findViewById(R.id.delete_button).setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        itemView.setEnabled(false);
                        // OR view.setClickable(false);
                    }
                });
        return itemView;
    }

或者使用带有移除动画的 RecyclerView。

构建.gradle

compile 'com.android.support:recyclerview-v7:23.2.1'

活动主文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layoutManager="android.support.v7.widget.LinearLayoutManager" />
</RelativeLayout>

my_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/value_text"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"/>

    <Button
        android:id="@+id/delete_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Delete"/>

</LinearLayout>

MainActivity.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<String> items = new ArrayList<>(
            Arrays.asList("first", "second", "third"));

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        RecyclerView myRecyclerView = (RecyclerView)
                findViewById(R.id.my_recycler_view);
        myRecyclerView.setAdapter(new MyAdapter());
    }

    private class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            return new MyViewHolder(LayoutInflater.from(MainActivity.this)
                    .inflate(R.layout.my_item, parent, false));
        }

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            holder.bind(position);
        }

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

        public class MyViewHolder extends RecyclerView.ViewHolder {

            private TextView valueTextView;
            private Button deleteButton;

            public MyViewHolder(View itemView) {
                super(itemView);
                valueTextView = (TextView) itemView.findViewById(R.id.value_text);
                deleteButton = (Button) itemView.findViewById(R.id.delete_button);
                deleteButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        int position = (int) v.getTag();
                        items.remove(position);
                        notifyItemRemoved(position);
                        notifyItemRangeChanged(position, items.size());
                    }
                });
            }

            public void bind(int position) {
                valueTextView.setText(items.get(position));
                deleteButton.setTag(position);
            }
        }
    }
}