استفاده از دیتابیس sqlite

سلام .
من تجربه بالایی ندارم و تا جایی که دیدم تو سایتای مختلف، از روش SQLiteOpenHelper استفاده کردن.

این هم یه قطعه کد. فک کنم کمکتون کنه.

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Build;
import android.os.Environment;
import android.util.Log;
import android.widget.Toast;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by Masoud on 7/3/2017.
 */

public class DatabaseHandler extends SQLiteOpenHelper {

    private static String DB_NAME = "contacts.sqlite";
    private static String TBL_NAME = "tbl_books";
    private static String DB_PATH = "";
    private static String TAG = "DB";

    private Context context;
    private SQLiteDatabase database;

    public DatabaseHandler(Context context) {
        super(context, DB_NAME, null, 1);
        this.context = context;

        if ((Build.VERSION.SDK_INT) > 15) {
            DB_PATH = context.getApplicationInfo().dataDir + "/";
        } else {
            DB_PATH = Environment.getDataDirectory() + "/data/" + context.getPackageName() + "/";
        }

        DB_PATH += DB_NAME;


    }


    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        /* do nothing in this block */

    }

    private boolean dbExist() {
        File file = new File(DB_PATH);
        if (file.exists()) {
            Log.i(TAG, "Database already exist");
            return true;
        } else
            return false;

    }

    private boolean copyDB() {

        Log.i(TAG, "Path of data is : " + DB_PATH);
        try {
            String path = DB_PATH;
            Log.i(TAG, "path : " + path);

            OutputStream outputStream = new FileOutputStream(path);
            InputStream inputStream = context.getAssets().open(DB_NAME);

            byte[] buffer = new byte[1024];
            int length = 0;

            while ((length = inputStream.read(buffer)) > 0) {
                outputStream.write(buffer, 0, length);
            }

            outputStream.flush();
            outputStream.close();
            inputStream.close();
            Toast.makeText(context, "Database Copied", Toast.LENGTH_SHORT).show();
            return true;


        } catch (Exception e) {
            /* do no thing in this block */
            Log.i(TAG, "There is a problem in copy of data base from copyDB method ... Check it");
            return false;
        }
    }

    public void openDB() {
        if (dbExist()) {
            try {

                File file = new File(DB_PATH);
                Log.i(TAG, "file pah: " + file.getAbsolutePath());
                database = SQLiteDatabase.openDatabase(file.getAbsolutePath(), null, SQLiteDatabase.OPEN_READWRITE);
                Toast.makeText(context, "Data Base Already Exist", Toast.LENGTH_SHORT).show();

            } catch (Exception e) {
                /* do n thing in tis block */
            }
        } else {
            if (copyDB()) {
                openDB();
            }
        }
    }


    @Override
    public synchronized void close() {
        database.close();
        Toast.makeText(context, "DataBase Closed", Toast.LENGTH_SHORT).show();
    }
}