Working with SQLite in two simple classes

AndroidSQLIteDatabaseExample.java

package com.github.pedrovgs.example.storage;

import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabaseLockedException;
import android.database.sqlite.SQLiteOpenHelper;
import android.support.annotation.NonNull;
import com.github.pedrovgs.example.logger.Logger;

public class SQLDelightStorage {

  private static final Object DB_LOCK = new Object();

  private final SQLiteOpenHelper openHelper;

  public SQLDelightStorage(SQLiteOpenHelper openHelper) {
    this.openHelper = openHelper;
  }

  protected void executeTransaction(Transaction transaction) {
    executeTransaction(transaction, new EmptyErrorListener());
  }

  protected void executeTransaction(Transaction transaction, @NonNull ErrorListener errorListener) {
    synchronized (DB_LOCK) {
      Logger.d("Start writing a DB transaction");
      SQLiteDatabase database = null;
      try {
        database = openHelper.getWritableDatabase();
        database.beginTransaction();
        transaction.execute(database);
        database.setTransactionSuccessful();
      } catch (SQLiteDatabaseLockedException e) {
        Logger.e(e.getMessage());
        errorListener.onUnrecoverableError();
      } finally {
        if (database != null) {
          database.endTransaction();
          database.close();
        }
        Logger.d("Write DB transaction finished");
      }
    }
  }

  protected <T> T read(Read<T> read) {
    return read(read, new EmptyErrorListener());
  }

  protected <T> T read(Read<T> read, @NonNull ErrorListener errorListener) {
    synchronized (DB_LOCK) {
      Logger.d("Start reading from DB");
      T result = null;
      SQLiteDatabase database = null;
      try {
        database = openHelper.getWritableDatabase();
        result = read.read(database);
      } catch (SQLiteDatabaseLockedException e) {
        Logger.e(e.getMessage());
        errorListener.onUnrecoverableError();
      } finally {
        Logger.d("End reading from DB");
        if (database != null) {
          database.close();
        }
      }
      return result;
    }
  }

  public interface Read<T> {
    T read(SQLiteDatabase database);
  }

  public interface Transaction {
    void execute(SQLiteDatabase database);
  }

  public interface ErrorListener {
    void onUnrecoverableError();
  }

  private static class EmptyErrorListener implements ErrorListener {
    @Override public void onUnrecoverableError() {
    }
  }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package com.github.pedrovgs.example.storage;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Build;
import com.github.pedrovgs.example.BuildConfig;
import com.github.pedrovgs.example.storage.ConfigModel;
import com.github.pedrovgs.example.logger.Logger;
import com.github.pedrovgs.example.storage.MetricModel;
import com.github.pedrovgs.example.ReportModel;

public class SQLDelightfulOpenHelper extends SQLiteOpenHelper {

  private static SQLDelightfulOpenHelper INSTANCE;

  private static final String DB_NAME = "dbname";
  private static final int DB_VERSION = BuildConfig.VERSION_CODE;
  private static final String REPORT_TIMESTAMP_INDEX =
      "CREATE INDEX search_report_timestamp ON report (report_timestamp DESC)";
  private static final String REPORT_ID_INDEX = "CREATE INDEX report_id ON metric (report_id)";

  public static synchronized SQLDelightfulOpenHelper getInstance(Context context) {
    if (INSTANCE == null) {
      INSTANCE = new SQLDelightfulOpenHelper(context);
    }
    return INSTANCE;
  }

  private SQLDelightfulOpenHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
  }

  @Override public void onConfigure(SQLiteDatabase db) {
    super.onConfigure(db);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
      db.setForeignKeyConstraintsEnabled(true);
    }
  }

  @Override public void onCreate(SQLiteDatabase db) {
    Logger.d("Database onCreate method invoked");
    createTables(db);
  }

  @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if (oldVersion != newVersion) {
      dropTables(db);
      createTables(db);
    }
  }

  private void createTables(SQLiteDatabase db) {
    db.execSQL(ConfigModel.CREATE_TABLE);
    db.execSQL(ReportModel.CREATE_TABLE);
    db.execSQL(MetricModel.CREATE_TABLE);
    db.execSQL(REPORT_TIMESTAMP_INDEX);
    db.execSQL(REPORT_ID_INDEX);
  }

  private void dropTables(SQLiteDatabase db) {
    dropTable(db, ConfigModel.TABLE_NAME);
    dropTable(db, ReportModel.TABLE_NAME);
    dropTable(db, MetricModel.TABLE_NAME);
  }

  private void dropTable(SQLiteDatabase db, String tableName) {
    db.execSQL("DROP TABLE " + tableName);
  }
}