Error in delete button

Question

Good Afternoon, I made a delete method in my database and called it in my Activity, only my problem is that when I click on the button it doesn’t happen anything, and doesn’t present me any error in Logcat, someone would know to help me?

Dbhelper:

package Base;

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 DbHelper extends SQLiteOpenHelper {

    private static final String NAME_BASE = "Resultados";
    private static final int VERSION_BASE = 1;

    public DbHelper(Context context) {

        super(context, NAME_BASE, null, VERSION_BASE);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String sqlCreateTableResultado = "CREATE TABLE resultado("
                + "id INTEGER PRIMARY KEY AUTOINCREMENT,"
                + "TimeCasa TEXT,"
                + "TimeFora TEXT,"
                + "GolsCasa INTEGER,"
                + "GolsFora INTEGER"+")";

        db.execSQL(sqlCreateTableResultado);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        String sqlDropTableResultado = "DROP TABLE resultado";

        db.execSQL(sqlDropTableResultado);

        onCreate(db);

    }

    public void insertResultado(Esporte resultado){
        SQLiteDatabase db = getWritableDatabase();

        ContentValues valores = new ContentValues();
        valores.put("TimeCasa", resultado.getNomeTimeUm());
        valores.put("TimeFora", resultado.getNomeTimeDois());
        valores.put("GolsCasa", resultado.getValorUm());
        valores.put("GolsFora", resultado.getValorDois());

        db.insert("resultado", null, valores);

        db.close();
    }

    public List<Esporte> selectTodosResult(){
        List<Esporte> listResult = new ArrayList<Esporte>();
        SQLiteDatabase db = getReadableDatabase();

        String sqlSelectTodosResult = "SELECT * FROM resultado";

        Cursor c = db.rawQuery(sqlSelectTodosResult, null);

        if (c.moveToFirst()){
            do {
                Esporte onde = new Esporte();
                onde.setId(c.getInt(0));
                onde.setNomeTimeUm(c.getString(1));
                onde.setNomeTimeDois(c.getString(2));
                onde.setValorUm(c.getInt(3));
                onde.setValorDois(c.getInt(4));

                listResult.add(onde);
            }
            while (c.moveToNext());
        }

        db.close();
        return listResult;
     }

    public void delete(){
        SQLiteDatabase db = getReadableDatabase();
        String sqlSelectTodosResult = "DELETE * FROM resultado";
        Cursor c = db.rawQuery(sqlSelectTodosResult, null);
    }

}

My Activity:

package com.allsport.miyonic.allsport;

import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.ArrayAdapter;
        import android.widget.Button;
        import android.widget.ListView;
        import java.util.List;

        import Base.DbHelper;
        import Base.Esporte;

        import static android.os.FileObserver.DELETE;

public class ResultSimples extends AppCompatActivity {

    private ListView lista;
    private Button apagar;

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

        lista = (ListView) findViewById(R.id.ListaTimes);
        apagar = (Button) findViewById(R.id.btndeletar);

        apagar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                DbHelper dd = new DbHelper(ResultSimples.this);
                dd.delete(); // É necessário passar o parâmetro
            }
        });
    }

    @Override
    public void onResume(){
        super.onResume();

        DbHelper dbhe = new DbHelper(this);
        List<Esporte> listaResultPartida = dbhe.selectTodosResult();

        ArrayAdapter<Esporte> adp = new ArrayAdapter<Esporte>(this, android.R.layout.simple_list_item_1, listaResultPartida);

        lista.setAdapter(adp);
    }


}

Thank you...

Answer 1

First of all, d.delete("resultado", "id = " + id, null); is a security breach. You are allowing an attack by calling SQL Injection. This third parameter exists precisely for this, avoid SQL Injection. Even if in this specific case it is impossible to practice an injection, it is better to be careful and not accustomed to writing SQL sentences in this way.

So this code should be

public void delete(long id){
    SQLiteDatabase d = getWritableDatabase();
    if (id > -1) {
        String[] whereArgs = new String[] { String.valueOf(id) };
        d.delete("resultado", "id=?", whereArgs);        
    }
    d.close();
}

The problem pointed out in the question is that the method delete inside DbHelper, asks as parameter a long and nothing is being passed

apagar.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        DbHelper dd = new DbHelper(ResultSimples.this);
        dd.delete(PARAMETRO_AQUI); // É necessário passar o parâmetro
    }
});

Answer 2

The error is in the parameter that the method delete are receiving

public void delete(long id){
    SQLiteDatabase d = getWritableDatabase();
    if (id > -1) {
        d.delete("resultado", "id = " + id, null);
    }
    d.close();
}

He’s expecting a long and you’re not passing anything, it generates the error.

When it’s time to call

dd.delete();

You must pass this id together or remove this parameter there from the method.

---

Update ():

Leave your method this way

public void delete(){
   SQLiteDatabase d = getWritableDatabase();
   d.delete("resultado", null, null);
   d.close();
}

And then you can call

dd.delete();