File Permission

File Permission.kt

MainActivity.kt:

package com.example.filepermission

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import java.io.BufferedReader
import java.io.FileOutputStream
import java.io.InputStreamReader
import java.lang.Exception

class MainActivity : AppCompatActivity() {
    private lateinit var fileName:EditText
    private lateinit var fileContent:EditText
    private lateinit var btnSave:Button
    private lateinit var btnLoad:Button
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        init()
    }
    fun init(){
        bindViews()
        btnSave.setOnClickListener {
            try {
                val name = fileName.text.toString()
                val content = fileContent.text.toString()
                val fileOutputStream = openFileOutput(name, MODE_PRIVATE)
                fileOutputStream.write(content.toByteArray())
                Toast.makeText(this,"File Saved",Toast.LENGTH_SHORT)
            }catch (e:Exception){
                println(e)
            }
        }
        btnLoad.setOnClickListener {
            try {
                val name = fileName.text.toString()
                val fileInputStream = openFileInput(name)
                val inputStreamReader = InputStreamReader(fileInputStream)
                val bufferedReader = BufferedReader(inputStreamReader)
                val txt = bufferedReader.readText()
                fileContent.setText(txt)
                Toast.makeText(this,"File Loaded",Toast.LENGTH_SHORT)
            }catch (e:Exception){
                Toast.makeText(this,e.message,Toast.LENGTH_SHORT)
            }
        }
    }

    fun bindViews(){
        fileName = findViewById(R.id.file_name)
        fileContent = findViewById(R.id.file_content)
        btnSave = findViewById(R.id.btn_save)
        btnLoad = findViewById(R.id.btn_load)
    }
}
_____________________________________________________________________

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="15dp"
    android:layout_marginTop="20dp"
    tools:context=".MainActivity">

    <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="filename"
            android:textSize="21sp"
            android:layout_marginRight="10dp"/>
        <EditText
            android:id="@+id/file_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:ems="10"
            android:inputType="text"
            android:text="file.txt" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="content"
            android:textSize="21sp"
            android:layout_marginRight="10dp"/>

        <EditText
            android:id="@+id/file_content"
            android:layout_width="wrap_content"
            android:layout_height="193dp"
            android:layout_weight="1"
            android:ems="10"
            android:inputType="text" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:weightSum="2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_save"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:text="save"
            android:layout_margin="5dp"/>

        <Button
            android:id="@+id/btn_load"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:text="load"
            android:layout_margin="5dp"/>
    </LinearLayout>

</LinearLayout>