Deleting items in a listView and database

Question

I am trying to delete objects in a listView and database at the same time after you have clicked the item in the listView. I'm tying to make it open an alert dialog before deleting the item. I have read many other stack overflow questions about this such as :

how can i delete an item from listview and also database

delete a specific item from listview stored in database in android application

Delete item from database - ListView - Android

And many others...none of them I find very helpful. Any suggestions?

Main_Activity:

public class New_Recipe extends AppCompatActivity {

Button add, done;
EditText Recipe_Name, Recipe_Item, Recipe_Steps;
String search;
WebView webView;
DatabaseHelper databaseHelper;
ListView ItemsList;
Context context = this;
SQLiteDatabase sqLiteDatabase;
Cursor cursor;
RecipeListAdapter listAdapter;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new__recipe);
    setTitle("New Recipe");
    add = (Button) findViewById(R.id.button2);
    done = (Button) findViewById(R.id.button);
    Recipe_Name = (EditText) findViewById(R.id.editText);
    Recipe_Item = (EditText) findViewById(R.id.editText2);
    Recipe_Steps = (EditText) findViewById(R.id.editText3);
    webView = (WebView) findViewById(R.id.webView);
    ItemsList = (ListView) findViewById(R.id.listView);
    listAdapter = new RecipeListAdapter(getApplicationContext(), R.layout.recipe_textview);
    context = this;
    AddData();



}
//When the add button is pressed
public void AddData() {
  add.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          String item = Recipe_Item.getText().toString();

          databaseHelper = new DatabaseHelper(context);
          sqLiteDatabase = databaseHelper.getWritableDatabase();

          databaseHelper.addItems(item, sqLiteDatabase);

          Toast.makeText(getBaseContext(), "Item inserted", Toast.LENGTH_LONG).show();

          databaseHelper.close();

          ItemsList.setAdapter(listAdapter);

          databaseHelper = new DatabaseHelper(getApplicationContext());
          sqLiteDatabase = databaseHelper.getReadableDatabase();

          cursor = databaseHelper.getItems(sqLiteDatabase);

          if (cursor.moveToFirst()) {
              do {

                  String items;

                  items = cursor.getString(0);

                  RecipeDataProvider dataProvider = new RecipeDataProvider(items);

                  listAdapter.add(dataProvider);

              } while (cursor.moveToNext());
          }
      }

  });

}







public void onSearch(View v) {
    search = "Recipes";
    webView.loadUrl("https://www.google.com/search?q=" + search);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_new__recipe, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

DatabaseHelper class:

public class DatabaseHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 5;
public static final String DATABASE_NAME = "Recipes.db";
public static final String CREATE_QUERRY = "create table " + RecipeContract.RecipeEntry.TABLE_NAME + "( _ID INTEGER PRIMARY KEY, NAME text, ITEMS text, STEPS text)";


public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    Log.d("Recipe Database", "Database should be made!");
}


@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(CREATE_QUERRY);
    Log.d("Recipe Database", "Table should be made!");
}

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

}

public void addItems(String items, SQLiteDatabase db)
{
    ContentValues values = new ContentValues();

    values.put(RecipeContract.RecipeEntry.COL2,items);

    db.insert(RecipeContract.RecipeEntry.TABLE_NAME,null,values);

    Log.e("Recipe Database","Item should be added to the table!");

}
public Cursor getItems(SQLiteDatabase db)
{
    Cursor cursor;
    String[] projections = {RecipeContract.RecipeEntry.COL2};

cursor = db.query(RecipeContract.RecipeEntry.TABLE_NAME,projections,null,null,null,null,null);

    return cursor;
}

ListViewAdapter:

public class RecipeListAdapter extends ArrayAdapter {

List list = new ArrayList();

public RecipeListAdapter(Context context, int resource) {
    super(context, resource);
}

static class LayoutHandler
{
    TextView ITEM;
}


@Override
public void add(Object object) {
    super.add(object);
    list.add(object);
}

@Override
public int getCount() {
    return super.getCount();
}

@Override
public Object getItem(int position) {
    return super.getItem(position);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View row = convertView;

    LayoutHandler layoutHandler;


    if (row == null)
    {

        LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = layoutInflater.inflate(R.layout.recipe_textview,parent,false);

        layoutHandler = new LayoutHandler();

        layoutHandler.ITEM = (TextView) row.findViewById(R.id.tx_items);

        row.setTag(layoutHandler);

    } else {

        layoutHandler = (LayoutHandler) row.getTag();
    }

    RecipeDataProvider dataProvider = (RecipeDataProvider) this.getItem(position);
    layoutHandler.ITEM.setText(dataProvider.getItems().toString());

    return row;
}

EDIT: my updated Main_Activity class

public class New_Recipe extends AppCompatActivity {

Button add, done;
EditText Recipe_Name, Recipe_Item, Recipe_Steps;
String search;
WebView webView;
DatabaseHelper databaseHelper;
ListView ItemsList;
Context context = this;
SQLiteDatabase sqLiteDatabase;
Cursor cursor;
RecipeListAdapter listAdapter;
List<New_Recipe> list = new ArrayList<>();
private int id;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new__recipe);
    setTitle("New Recipe");
    add = (Button) findViewById(R.id.button2);
    done = (Button) findViewById(R.id.button);
    Recipe_Name = (EditText) findViewById(R.id.editText);
    Recipe_Item = (EditText) findViewById(R.id.editText2);
    Recipe_Steps = (EditText) findViewById(R.id.editText3);
    webView = (WebView) findViewById(R.id.webView);
    ItemsList = (ListView) findViewById(R.id.listView);
    listAdapter = new RecipeListAdapter(getApplicationContext(), R.layout.recipe_textview);
    context = this;

    AddData();


    ItemsList.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
            Object getSelectedItem = list.get(position);

            databaseHelper.deleteItem(getSelectedItem);
            listAdapter.deleteitem(getSelectedItem);

            return true;
        }
    });



}

public New_Recipe(){

}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

Answer 1

You can use this method for deleting a row from DatabaseHelper class :

public void deleteItem(Object item) {
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_NAME, KEY_ID + " = ?",
            new String[]{String.valueOf(item.getId())});
    db.close();
}

And then you need also one method for deleting object from adapter :

public void deleteItem(Object item) {
    listArray.remove(item);
    notifyDataSetChanged();
}

Now you can call all this method in activity like this :

Let's say that you want to delete all this by clicking long on list item :

listView.setOnItemLongClickListener(new OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                int pos, long id) {
            Object getSelectedItem = arrayList.get(pos);

            dataBaseHelper.deleteItem(getSelectedItem);
            adapter.deleteItem(getSelectedItem);

            return true;
        }
    }); 

UPDATED:

You need before you try to call method getId() to create that method in your class. So you need to create get and setter methods in your class, something like this:

STEP BY STEP:

1. Change your class New_Recipe to MainActivity. If you are getting an error, just highlight that error and there you will see "rename file".

   2. Create a new class outside your main class and call it NewRecipe:

      public class NewRecipe {

      private int id;

      private String title;

      public NewRecipe() { // empty constructor }

      public int getId() { return id; }

      public void setId(int id) { this.id = id; } }

And now you can do everything i have explained earlier.

Answer 2

You need a function deletein DatabaseHelper class

public boolean delete(long rowId) {
      return db.delete(TABLE_NAME, KEY_ROWID + "=" + rowId, null) > 0;
    }

You need a function in the Activity deleteItem() similar to addItems()

public void deleteItem(){

//Based on some logic,find the rowID of the table which needs to be deleted and call delete function of DatabaseHelper class.
}

Similarily in your ListViewAdapter, you need to define a method delete

public void delete(Object object) {
    list.remove(object);
    //To update the ListView in Android
    this.notifyDataSetChanged();
}