SingletonDatabase.java

/**
 * create custom DatabaseHelper class that extends SQLiteOpenHelper
 */
public class DatabaseHelper extends SQLiteOpenHelper { 

    private static DatabaseHelper mInstance = null;

    private static final String DATABASE_NAME = "databaseName";
    private static final String DATABASE_TABLE = "tableName";
    private static final int DATABASE_VERSION = 1;

    private Context mCxt;
 
    public static DatabaseHelper getInstance(Context ctx) {
        /** 
         * use the application context, which will ensure that you 
         * don't accidentally leak an Activity's context. 
         * (see this article for more information: 
         * http://developer.android.com/resources/articles/avoiding-memory-leaks.html)
         */
        if (mInstance == null) {
            mInstance = new DatabaseHelper(ctx.getApplicationContext());
        }
        return mInstance;
    }
    
    /**
     * constructor should be private to prevent direct instantiation.
     * make call to static factory method "getInstance()" instead.
     */
    private DatabaseHelper(Context ctx) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.mCtx = ctx;
    }
}