Fetch data from a particular column and display them in a Spinner

Question

I’m searching for the Sqlite database records and displaying on a Spinner, but Spinner is displaying all the table records, and I need to display only the records of a particular column .

I tried to change the query :

Of :

 String selectQuery = "SELECT * FROM " + TABLE_LABELS;

for :

 String selectQuery = "SELECT modelo FROM " + TABLE_LABELS;

However an error occurred on the cursor.

Erro : Failed to read row 0, column 1 from a CursorWindow which has 12 rows, 1 columns.
java.lang.IllegalStateException: Couldn't read row 0, col 1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.

Follows below code :

package com.example.d2;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

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

public class DatabaseHandler extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 2;
    private static final String DATABASE_NAME = "Medidores";

    private static final String TABLE_LABELS = "labels";

    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_MODELO = "modelo";    

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CATEGORIES_TABLE = "CREATE TABLE " + TABLE_LABELS + "("+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT," + KEY_MODELO + " TEXT)"; // removi o modelo e seu tipo
        db.execSQL(CREATE_CATEGORIES_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LABELS);

        onCreate(db);
    }

    public void insertLabel(String nome,String modelo) { // alterei de void para long
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME , nome);
        values.put(KEY_MODELO, modelo);

        db.insert(TABLE_LABELS, null, values);
        db.close(); // Closing database connection
    }

    public List<String> getAllLabels() {
        List<String> labels = new ArrayList<String>();

        // Select All Query
        String selectQuery = "SELECT * FROM " + TABLE_LABELS;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        if (cursor.moveToFirst()) {
            do {
                labels.add(cursor.getString(1));

            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning lables
        return labels;
    }

    public List<String> BuscaModelos() {
        List<String> modelos = new ArrayList<String>();

        String selectQuery = "SELECT  * FROM " + TABLE_LABELS;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        if (cursor.moveToFirst()) {
            do {
                modelos.add(cursor.getString(1));

            } while (cursor.moveToNext());
        }

        cursor.close();
        db.close();

        return modelos;
    }
}

Answer 1

The Cursor Android starts with index 0.

Exchange the modelos.add(cursor.getString(1)); for modelos.add(cursor.getString(0));.

You can refer to the index of a column based on its name, using the getColumnIndex(String name) to make no mistake.

if (cursor.moveToFirst()) {
    int indiceDaColuna = cursor.getColumnIndex("NOME_DA_COLUNA");

    do {
        modelos.add(cursor.getString(indiceDaColuna));
    } while (cursor.moveToNext());
}

Beware, because the getColumnIndex to return -1 if there is no column.