gistfile1.java

public class DatabaseHelper extends SQLiteOpenHelper { 
 
  private static DatabaseHelper instance = null;
 
  private static final String DATABASE_NAME = "dbname.db";
  private static final int DATABASE_VERSION = 1;
 
  public synchronized static DatabaseHelper getInstance(Context ctx) {
      
    // Use the application context, which will ensure that you 
    // don't accidentally leak an Activity's context.    
    if (instance == null) {
        instance = new DatabaseHelper(ctx.getApplicationContext());
    }
    return instance;
  }
     
  private DatabaseHelper(Context ctx) {
      super(ctx, DATABASE_NAME, null, DATABASE_VERSION);
  }

  ...
}