Как удалить сообщение из списка и базы данных

Question

ниже - мой код Я хочу добавить сообщение для удаления списка, когда пользователь нажимает на длинное нажатие выбранного сообщения, удалит из списка, а также базу данных поможет мне, как это сделать im imign протектора в моем коде, так что как удалить выбранную форму представления списка сообщений и базу данных?

public class MsgActivity extends BackBaseActivity{ 
    ImageView back; 
    Button writemsg; 
    ListView msglist; 
    List<MessageModel> msgarray; 
    MessageAdapter msgadapter; 
    ImageView scroll_down; 
ImageView scroll_up; 
int x = 1; 
public static Activity msgactivity;; 
Handler handle = new Handler() { 
    public void handleMessage(android.os.Message msg) { 
     super.handleMessage(msg); 
     CommonObjects.hideProgress(); 

      msgadapter = new MessageAdapter(MsgActivity.this, 
      msgarray); 


     msglist.setAdapter(msgadapter); 
      }catch (Exception e) { 
       // TODO: handle exception 
      } 
     } 
     if(msg.what == 1){ 
      Toast.makeText(MsgActivity.this, "No Messages", 
        Toast.LENGTH_SHORT).show(); 
     } 

    } 

}; 
@Override 
protected void onRestart() { 
    if(CommonObjects.getLogoutreject().equals("1") && CommonObjects.logout){ 

     finish(); 

    } 
    super.onRestart(); 
} 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    // TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.msgactivity); 
    back = (ImageView)findViewById(R.id.magback); 
    msglist = (ListView)findViewById(R.id.msglist);   
    msgactivity = this; 
    CommonObjects.showProgress(MsgActivity.this, "Loading messages");   
    new Thread() { 
     public void run() { 
      Looper.prepare(); 
      try{  
       DatabaseHandler db = new 
         DatabaseHandler(MsgActivity.this); 
      msgarray = db.getAllmesages(); 

      android.os.Message alertMessage = new android.os.Message(); 
      alertMessage.what = 2; 
      handle.sendMessage(alertMessage); 
      }catch (Exception e) { 
       e.getStackTrace(); 
       android.os.Message alertMessage = new 
         android.os.Message(); 
       alertMessage.what = 1; 
       handle.sendMessage(alertMessage); 
      } 
     } 
    }.start(); 
    } 

Answer 1

Попробуйте вот так.

lv.setOnItemLongClickListener(new OnItemLongClickListener() { 
     // setting onItemLongClickListener and passing the position to the function 
        @Override 
     public boolean onItemLongClick(AdapterView<?> arg0, View arg1, 
       int position, long arg3) { 

       String[] delete = names2.get(i); 
       String idString = delete[0]; 
       long idLong = Long.valueOf(idString); 
       Log.d("Deleting...", idLong + ""); 
       dataManipulator.delete(idLong); 
       names2.remove(i); 
     } 
    }); 

Где names2 - ваш массив List.

и в классе Datamanipulator добавить следующие

public boolean delete(long rowId) { 
     /** this method deletes by id, the first column in your database */ 
     return db.delete(TABLE_NAME, KEY_ROWID + "=" + rowId, null) > 0; 
    } 

Answer 2

, если вы хотите удалить все данные из ListView и Databse просто выполнить эту opreation

в классе mainactivity

delete.setOnClickListener(new OnClickListener() { 

    @Override 
    public void onClick(final View v) { 
     // TODO Auto-generated method stub 


       DatabaseHandler dBHandler = new DatabaseHandler(
        activity.getApplicationContext()); 
       dBHandler.Delete_Contact(user_id); 
       Main_Screen.this.onResume(); 

      } 
      }); 

и используйте полевой код вашей базы данных

// Deleting single contact 
public void Delete_Contact(int id) { 
    SQLiteDatabase db = this.getWritableDatabase(); 
    db.delete(TABLE_CONTACTS, KEY_ID + " = ?", 
      new String[] { String.valueOf(id) }); 
    db.close(); 
} 

Answer 3

DataBaseManager data = new DataBaseManager(context.getApplicationContext()); 

       String QUERY = "SELECT * FROM Cart Where id= "your id"; 

        Cursor cursor = data.selectQuery(QUERY); 
    int count = cursor.getCount(); 
        if (count <= 0) { 

       } 
      else { 
       data.Delete("YOUR DATABASE NAME", "YOUR ID"); 
       list.remove(position); 
       notifyDataSetChanged(); 
       } 

DatabaseMangerClass

 public class DataBaseManager extends SQLiteOpenHelper { 

      // The Android's default system path of your application database. 

      @SuppressLint("SdCardPath") 
      private static String DB_PATH = "data/data/com.Salsoft.pharmapacks/"; 
      private static String DB_NAME = "Cart.sqlite"; 
      private SQLiteDatabase myDataBase; 
      private SQLiteDatabase myData; 
      private Context myContext; 

      // /data/data/com.salsoft.savingdata/db/SavingData.sqlite 

      /** 
      * Constructor Takes and keeps a reference of the passed context in order to 
      * access to the application assets and resources. 
      * 
      * @param context 
      */ 
      public DataBaseManager(Context context) { 
       super(context, DB_NAME, null, 1); 
       this.myContext = context; 
       Boolean isSDPresent = android.os.Environment.getExternalStorageState() 
         .equals(android.os.Environment.MEDIA_MOUNTED); 

       if (isSDPresent) { 
        // yes SD-card is present 
       } else { 
        // Sorry 
       } 
      } 

      /** 
      * Creates a empty database on the system and rewrites it with your own 
      * database. 
      * */ 
      public void createDataBase() throws IOException { 

       boolean dbExist = checkDataBase(); 
       if (dbExist) { 
        // do nothing - database already exist 
       } else { 
        File directory = new File(DB_PATH); 
        directory.mkdirs(); 
        CopyFiles(); 
       } 
      } 

      private void CopyFiles() { 
       try { 
        InputStream is = myContext.getAssets().open(DB_NAME); 
        File outfile = new File(DB_PATH, DB_NAME); 
        outfile.getParentFile().mkdirs(); 
        outfile.createNewFile(); 

        if (is == null) { 
         throw new RuntimeException("stream is null"); 
        } else { 
         FileOutputStream out = new FileOutputStream(outfile); 
         byte buf[] = new byte[128]; 
         do { 
          int numread = is.read(buf); 
          if (numread <= 0) 
           break; 
          out.write(buf, 0, numread); 
         } while (true); 

         is.close(); 
         out.close(); 
        } 

       } catch (IOException e) { 
        throw new RuntimeException(e); 
       } 

      } 

      /** 
      * Check if the database already exist to avoid re-copying the file each 
      * time you open the application. 
      * 
      * @return true if it exists, false if it doesn't 
      */ 
      private boolean checkDataBase() { 

       SQLiteDatabase checkDB = null; 

       try { 
        String myPath = DB_PATH + DB_NAME; 
        checkDB = SQLiteDatabase.openDatabase(myPath, null, 
          SQLiteDatabase.OPEN_READWRITE); 

       } catch (SQLiteException e) { 

       } 

       if (checkDB != null) { 
        checkDB.close(); 
       } 

       return checkDB != null ? true : false; 
      } 

      public void openDataBase() throws SQLException { 

       // Open the database 
       String myPath = DB_PATH + DB_NAME; 
       myDataBase = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READWRITE); 
      } 

      @Override 
      public synchronized void close() { 
       if (myDataBase != null) 
        myDataBase.close(); 
       super.close(); 
      } 

      public void insert(String table, String num, ContentValues content) { 
       String myPath = DB_PATH + DB_NAME; 

       myData = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READWRITE); 
       myData.insert(table, num, content); 

      } 

      public void update(String tablename, ContentValues content, String productid) { 
       String myPath = DB_PATH + DB_NAME; 
       myData = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READWRITE); 
       myData.update(tablename, content, "productid = ?", 
         new String[] { productid }); 

      } 

      public void Delete(String tablename, String productid) { 
       String myPath = DB_PATH + DB_NAME; 
       myData = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READWRITE); 

       myData.delete(tablename, "productid = ?", new String[] { productid }); 

      } 

      @Override 
      public void onCreate(SQLiteDatabase db) { 
      } 

      @Override 
      public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
      } 

      // ---retrieve records--- 
      public Cursor selectQuery(String query) throws SQLException { 
       String myPath = DB_PATH + DB_NAME; 
       myData = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READONLY); 
       Cursor mCursor = myData.rawQuery(query, null); 
       mCursor.moveToFirst(); 
       myData.close(); 
       return mCursor; 
      } 

      // //////// For Insert And Update Data //////// 
      public void insert_update(String query) throws SQLException { 
       String myPath = DB_PATH + DB_NAME; 
       myData = SQLiteDatabase.openDatabase(myPath, null, 
         SQLiteDatabase.OPEN_READWRITE); 
       myData.execSQL(query); 
       myData.close(); 
      } 

     }