通过单击RecyclerView和SQLite数据库中的图像来删除项目

Question

我正在使用SQLite和RecyclerView创建一个待办事项应用程序，但是在单击图像即我的ivDelete时无法删除任务。我要删除已完成的任务。任何想法如何删除？任何帮助将不胜感激。

这是我的MainActivity：

public class MainActivity extends AppCompatActivity
{
    Button btn_tasks,btn_reminders,btn_about;
    ImageView img_addtask;
    RecyclerView contactView;
    DBHelper dbHelper;
    CustomAdapter mAdapter;
    private ArrayList<TaskClass> allContacts;
    @Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btn_tasks = findViewById(R.id.btn_task);
    btn_reminders = findViewById(R.id.btn_reminder);
    btn_about = findViewById(R.id.btn_about);
    img_addtask = findViewById(R.id.imageView);
    dbHelper = new DBHelper(this);
    contactView = findViewById(R.id.list);
    LinearLayoutManager layoutManager = new LinearLayoutManager(this);
    contactView.setLayoutManager(layoutManager);
    contactView.setHasFixedSize(true);
    allContacts = new ArrayList<>();
    allContacts = dbHelper.getTaskList();

    loadTaskList();

img_addtask.setOnClickListener(new View.OnClickListener() 
{
    @Override
    public void onClick(View view) 
    {
        addTask();
    }
 });
 btn_reminders.setOnClickListener(new View.OnClickListener() 
 {
     @Override
     public void onClick(View view) 
     {
         addReminder();
     }
   });

}

private void loadTaskList()
{
    ArrayList<TaskClass> taskList = dbHelper.getTaskList();
    if(mAdapter == null)
    {
        contactView.setVisibility(View.VISIBLE);
        mAdapter = new CustomAdapter(this,allContacts);
        contactView.setAdapter(mAdapter);
    }
    else
    {
        contactView.setVisibility(View.GONE);
        Toast.makeText(this, "There is no task in the database. Start 
adding now", Toast.LENGTH_LONG).show();
    }
}

private void addTask()
{
    Intent intent = new Intent(this,AddTask.class);
    startActivity(intent);
}
private void addReminder()
{
    Intent intent = new Intent(this,AddReminder.class);
    startActivity(intent);
}
}

这是我的DBHelper类：

public class DBHelper extends SQLiteOpenHelper 
{

private static final String DB_NAME = "Demo.db";
private static final int DB_VER = 1;
private static final String DB_TABLE = "Task";

DBHelper(Context context) 
{
    super(context, DB_NAME, null, DB_VER);
}

@Override
public void onCreate(SQLiteDatabase db) 
{
    db.execSQL(" CREATE TABLE " +DB_TABLE+" (ID INTEGER PRIMARY KEY AUTOINCREMENT, TaskName TEXT, dateStr TEXT)");
}

@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) 
{
    db.execSQL("DROP TABLE IF EXISTS "+DB_TABLE);
    onCreate(db);
}

void insertNewTask(TaskClass taskClass)
{
    ContentValues values = new ContentValues();
    SQLiteDatabase db= this.getWritableDatabase();
    values.put("TaskName",taskClass.getTaskName());
    values.put("dateStr", taskClass.getTaskDate());
    db.insert(DB_TABLE,null,values);
    db.close();
}



public ArrayList<TaskClass> getTaskList()
{
    String selectQuery = "SELECT  * FROM " + DB_TABLE;
    SQLiteDatabase db = this.getReadableDatabase();
    ArrayList<TaskClass> taskList = new ArrayList<>();
    Cursor cursor = db.rawQuery(selectQuery, null);
   if(cursor.moveToFirst())
   {
       do {
           String name =  cursor.getString(cursor.getColumnIndex("TaskName"));
           String date = cursor.getString(cursor.getColumnIndex("dateStr"));
           taskList.add(new TaskClass(name,date));
       }while (cursor.moveToNext());
   }
    cursor.close();
    return taskList;
}

}

这是CustomAdapter类：

    public CustomViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout, parent, false);
        return new CustomViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull CustomViewHolder viewHolder, final int position)
    {
        viewHolder.txtTask.setText(taskClass.get(position).getTaskName());
        viewHolder.txtDate.setText(taskClass.get(position).getTaskDate());
    }

    @Override
    public int getItemCount() {
        return taskClass.size();
    }
    public class CustomViewHolder extends RecyclerView.ViewHolder
    {
        TextView txtTask,txtDate;
        ImageView ivDelete;

        public CustomViewHolder(View itemView)
        {
            super(itemView);
            txtTask = itemView.findViewById(R.id.task_title);
            txtDate = itemView.findViewById(R.id.task_date);
            ivDelete = itemView.findViewById(R.id.ivDelete);
        }
    }

Answer 1

您可以在适配器的onBindViewHolder上的ivDelete上放置一个侦听器，然后从数据库中删除具有ID的任务。您将必须在DBHelper类上创建一个方法。

viewHolder.ivDelete.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        // TODO Call method to delete task

    }
});