ListView删除元素异常：删除最后一个而非目标元素

我需要实现ListView的视图添加与删除功能：点击ADD按钮添加对象（视图），长按列表项弹出窗口执行删除操作。目前其他功能正常，但删除时总是移除ArrayList的最后一个元素，而非长按选中的目标元素。我知道可以通过标记对象或索引实现，但不清楚如何结合现有程序架构适配。

现有代码 #

MainActivity.java

public class MainActivity extends AppCompatActivity {
    // Construct the data source
    ArrayList<User> arrayOfUsers = new ArrayList<User>();
    
    ListView listview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Create the adapter to convert the array to views
        UsersAdapter adapter = new UsersAdapter(this, arrayOfUsers);
        // Attach the adapter to a ListView
        ListView listView = (ListView) findViewById(R.id.book_list);
        listView.setAdapter(adapter);

        Button add = (Button)findViewById(R.id.add);
        // Activates method on yes button click
        add.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                arrayOfUsers.add(new User("test", "test"));
                adapter.notifyDataSetChanged();
            }
        });

        listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
                final int itemToDelete = i;
                // To delete the data from the App
                new AlertDialog.Builder(MainActivity.this)
                        .setIcon(android.R.drawable.ic_dialog_alert)
                        .setTitle("Are you sure?")
                        .setMessage("Do you want to delete this note?")
                        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                arrayOfUsers.remove(itemToDelete);
                                adapter.notifyDataSetChanged();
                            }
                        }).setNegativeButton("No", null).show();
                return true;
            }
        });
    }
}

UsersAdapter.java

public class UsersAdapter extends ArrayAdapter<User> {
    private ArrayList<User> users;
    public UsersAdapter(Context context, ArrayList<User> users) {
        super(context, 0, users);
        this.users = users;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        User user = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
        }
        // Lookup view for data population
        TextView tvName = (TextView) convertView.findViewById(R.id.tvName);
        TextView tvHome = (TextView) convertView.findViewById(R.id.tvHome);
        // Populate the data into the template view using the data object
        tvName.setText(user.name);
        tvHome.setText(user.hometown);

        EditText input_weight = (EditText) convertView.findViewById(R.id.weight);

        Button save = (Button) convertView.findViewById(R.id.save);
        // Activates method on yes button click
        save.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(getContext().getApplicationContext());
                SharedPreferences.Editor editor = pref.edit();
                String bw = String.valueOf(input_weight.getText());
                editor.putString("input_weight", bw);
                editor.commit(); // Saves body weight
                bw = pref.getString("body_weight", bw); // Gets body weight
                tvHome.setText(bw); // Displays body weight
            }
        });

        // Return the completed view to render on screen
        return convertView;
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/book_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:listitem="@layout/list_item"/>

    <Button
        android:id="@+id/add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ADD"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

list_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="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Name" />
    <EditText
        android:id="@+id/weight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:hint="Weight" />
    <TextView
        android:id="@+id/tvHome"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="HomeTown" />
    <Button
        android:id="@+id/save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save"
        android:focusable="false"
        />

</LinearLayout>

解决方案 #

1. 修复删除逻辑 #

直接通过Adapter的remove方法删除选中对象，避免索引关联错误：

listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
    @Override
    public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
        final User targetUser = adapter.getItem(i);
        new AlertDialog.Builder(MainActivity.this)
                .setIcon(android.R.drawable.ic_dialog_alert)
                .setTitle("确定删除？")
                .setMessage("你确定要删除这条记录吗？")
                .setPositiveButton("是", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int which) {
                        // Adapter的remove方法会自动更新数据源并刷新视图
                        adapter.remove(targetUser);
                    }
                }).setNegativeButton("否", null).show();
        return true;
    }
});

2. 优化Adapter的视图复用与数据存储 #

使用ViewHolder模式避免重复绑定点击事件，同时修复SharedPreferences的key冲突问题：

public class UsersAdapter extends ArrayAdapter<User> {
    public UsersAdapter(Context context, ArrayList<User> users) {
        super(context, 0, users);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
            holder = new ViewHolder();
            holder.tvName = convertView.findViewById(R.id.tvName);
            holder.tvHome = convertView.findViewById(R.id.tvHome);
            holder.input_weight = convertView.findViewById(R.id.weight);
            holder.save = convertView.findViewById(R.id.save);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        final User user = getItem(position);
        holder.tvName.setText(user.name);
        holder.tvHome.setText(user.hometown);

        // 绑定当前用户和位置到按钮Tag
        holder.save.setTag(user);
        holder.save.setTag(R.id.tag_position, position);

        holder.save.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                User currentUser = (User) view.getTag();
                int pos = (int) view.getTag(R.id.tag_position);
                SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(getContext());
                SharedPreferences.Editor editor = pref.edit();
                String bw = holder.input_weight.getText().toString().trim();
                // 用位置作为key后缀，避免不同item的数据互相覆盖
                editor.putString("weight_" + pos, bw);
                editor.apply();
                bw = pref.getString("weight_" + pos, bw);
                holder.tvHome.setText(bw);
                // 更新数据源对象，保持数据一致性
                currentUser.hometown = bw;
            }
        });

        return convertView;
    }

    static class ViewHolder {
        TextView tvName;
        TextView tvHome;
        EditText input_weight;
        Button save;
    }
}

3. 添加Tag ID定义 #

在res/values/ids.xml中添加位置Tag的ID（无该文件则新建）：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item name="tag_position" type="id"/>
</resources>

内容的提问来源于stack exchange，提问作者wickedesperatevirgin