мне задали проект "Библиотека" что бы программа принимала pdf файлы и показывала его. Работаю на android studio. оставил шаблон которым пользовался

package com.example.dbsqlite

import android.annotation.SuppressLint
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast

class MainActivity : AppCompatActivity() {
    @SuppressLint("Range")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val entN = findViewById<EditText>(R.id.enterName)
        val entA = findViewById<EditText>(R.id.enterAge)
        val btnAdd = findViewById<Button>(R.id.addData)
        val btnShow = findViewById<Button>(R.id.showData)
        val btnDrop = findViewById<Button>(R.id.dropData)
        val btnUpd = findViewById<Button>(R.id.updData)
        val shN = findViewById<TextView>(R.id.showName)
        val shA = findViewById<TextView>(R.id.showAge)

        btnAdd.setOnClickListener {
            val db = DBHelper(this)
            if (entN.text.trim().isEmpty() || entA.text.trim().isEmpty()){
                Toast.makeText(this, "Ma'lumot kiritilmadi",Toast.LENGTH_SHORT).show()
            }
            else{
                db.addData(entN.text.trim().toString(), entA.text.trim().toString().toInt())
                Toast.makeText(this, "Ma'lumot bazaga qo'shildi",Toast.LENGTH_SHORT).show()
                entN.text.clear()
                entA.text.clear()
            }
        }

        btnShow.setOnClickListener {
            val db = DBHelper(this)
            val cursor = db.showData()
            shN.text=""
            shA.text=""
            cursor.moveToFirst()
            shN.append(cursor.getString(cursor.getColumnIndex(DBHelper.COL_NAME))+"\n")
            shA.append(cursor.getString(cursor.getColumnIndex(DBHelper.COL_AGE))+"\n")

            while (cursor.moveToNext()){
                shN.append(cursor.getString(cursor.getColumnIndex(DBHelper.COL_NAME))+"\n")
                shA.append(cursor.getString(cursor.getColumnIndex(DBHelper.COL_AGE))+"\n")
            }
        }

        btnDrop.setOnClickListener {
            val db = DBHelper(this)

            if (!entN.text.isEmpty()){
                val result = db.dropData(entN.text.toString())
                if (result == -1){
                    Toast.makeText(this, "Ma'lumotlar mavjud emas",Toast.LENGTH_SHORT).show()
                }
                else{
                    if(!shN.text.equals(entN.text))
                    Toast.makeText(this, "Bunday yozuv yo'q",Toast.LENGTH_SHORT).show()
                    else
                    Toast.makeText(this, "Ma'lumot o'chirildi",Toast.LENGTH_SHORT).show()
                }
            }
        }

        btnUpd.setOnClickListener {
            val db = DBHelper(this)
            if (entN.text.trim().isEmpty() || entA.text.trim().isEmpty()){
                Toast.makeText(this, "Ma'lumot kiritilmadi",Toast.LENGTH_SHORT).show()
            }
            else{
                db.updateData(entN.text.trim().toString(), entA.text.trim().toString().toInt())
                Toast.makeText(this, "Ma'lumot yangilandi",Toast.LENGTH_SHORT).show()
                entN.text.clear()
                entA.text.clear()
            }
        }
    }
}

package com.example.dbsqlite

import android.content.ContentValues
import android.content.Context
import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper

class DBHelper(context: Context) : SQLiteOpenHelper(context, DB_NAME, null, DB_VERSION){
    override fun onCreate(p0: SQLiteDatabase) {
        val query = "CREATE TABLE "+TABLE_NAME+"("+
                COL_ID+" INTEGER PRIMARY KEY," +
                COL_NAME+" TEXT," +
                COL_AGE+" INTEGER)"
        p0.execSQL(query)
    }

    override fun onUpgrade(p0: SQLiteDatabase, p1: Int, p2: Int) {
        p0.execSQL("DROP TABLE IF EXISTS data")
        onCreate(p0)
    }

    fun addData(name:String, age:Int){
        val values = ContentValues()
        values.put(COL_NAME, name)
        values.put(COL_AGE, age)
        val db = this.writableDatabase
        db.insert(TABLE_NAME,null,values)
        db.close()
    }

    fun showData() : Cursor{
        val db = this.readableDatabase
        return db.rawQuery("SELECT * FROM " + TABLE_NAME, null)
    }

    fun dropData(name: String): Int {
        val db = this.writableDatabase
        return db.delete(TABLE_NAME, COL_NAME + "=?", arrayOf(name))
    }

    fun updateData(name: String, age: Int){
        val values = ContentValues()
        values.put(COL_NAME, name)
        values.put(COL_AGE, age)
        val db = this.writableDatabase
        db.update(TABLE_NAME,values, COL_NAME + "=?", arrayOf(name))
        db.close()
    }

    companion object{
        var DB_NAME = "myDB"
        var DB_VERSION = 1
        var TABLE_NAME = "data"
        var COL_ID = "id"
        var COL_NAME = "name"
        var COL_AGE = "age"
    }
}