// AndroidManifest.xml:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

// activity_external_storage_example.xml:
                                        <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ExternalStorageExample"
    android:padding="16dp"
    android:gravity="center"
    android:orientation="vertical">

    <EditText
        android:id="@+id/input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter your message" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="16dp"
        android:gravity="center">

        <Button
            android:id="@+id/b1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Save Data"
            android:textColor="@color/colorWhite"
            android:textAllCaps="false"
            android:background="@color/colorOrange"
            android:padding="16dp"
            android:layout_margin="16dp" />

        <Button
            android:id="@+id/b2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Display Data"
            android:textColor="@color/colorWhite"
            android:textAllCaps="false"
            android:background="@color/colorOrange"
            android:padding="16dp"
            android:layout_margin="16dp" />

    </LinearLayout>

    <TextView
        android:id="@+id/textDisplay"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="@color/colorAccent"
        android:textSize="20dp"
        android:padding="16dp"
        android:gravity="center" />

</LinearLayout>

                                    
                                  

                                    
                                        package com.example.widgets;

import android.content.ContextWrapper;
import android.os.Environment;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;

public class ExternalStorageExample extends AppCompatActivity {

    EditText editText;
    Button save, display;
    TextView textView;
    String mfiles = "Files";
    String filename = "m.txt";
    File file;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_external_storage_example);

        editText = findViewById(R.id.input);
        save = findViewById(R.id.b1);
        display = findViewById(R.id.b2);
        textView = findViewById(R.id.textDisplay);

        if (isExternalStorageWritable()) {
            save.setEnabled(false);
        } else {
            ContextWrapper contextWrapper = new ContextWrapper(getApplicationContext());
            file = new File(contextWrapper.getExternalFilesDir(mfiles), filename);
        }

        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                String msg = editText.getText().toString().trim();

                if (!msg.equals("")) {
                    try {

                        FileOutputStream fileOutputStream = new FileOutputStream(file);
                        fileOutputStream.write(msg.getBytes());
                        fileOutputStream.flush();
                        fileOutputStream.close();
                        editText.setText("");

                        Toast.makeText(getApplicationContext(), "Data saved successfully", Toast.LENGTH_SHORT).show();

                    } catch (Exception e) {
                        e.printStackTrace();
                    }

                } else {

                    Toast.makeText(getApplicationContext(), "Data is empty", Toast.LENGTH_SHORT).show();
                }
            }
        });

        display.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                try {

                    StringBuffer stringBuffer = new StringBuffer();
                    String message;

                    FileInputStream fileInputStream = new FileInputStream(file);
                    InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
                    BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

                    while ((message = bufferedReader.readLine()) != null) {

                        stringBuffer.append(message);
                    }

                    textView.setText("Message: " + stringBuffer.toString());

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

    }

    private boolean isExternalStorageWritable() {
        String s = Environment.getExternalStorageState();
        return !Environment.MEDIA_MOUNTED.equals(s);
    }

}
                                    
                                  

                                    
                                        package com.example.widgets

import android.content.ContextWrapper
import android.os.Environment
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import java.io.BufferedReader
import java.io.File
import java.io.FileInputStream
import java.io.FileOutputStream
import java.io.InputStreamReader

class ExternalStorageExample : AppCompatActivity() {

    private lateinit var editText: EditText
    private lateinit var save: Button
    private lateinit var display: Button
    private lateinit var textView: TextView
    private var mfiles = "Files"
    private var filename = "m.txt"
    private lateinit var file: File

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_external_storage_example)

        editText = findViewById(R.id.input)
        save = findViewById(R.id.b1)
        display = findViewById(R.id.b2)
        textView = findViewById(R.id.textDisplay)

        if (isExternalStorageWritable()) {
            save.isEnabled = false
        } else {
            val contextWrapper = ContextWrapper(applicationContext)
            file = File(contextWrapper.getExternalFilesDir(mfiles), filename)
        }

        save.setOnClickListener {
            val msg = editText.text.toString().trim()

            if (msg.isNotEmpty()) {
                try {
                    val fileOutputStream = FileOutputStream(file)
                    fileOutputStream.write(msg.toByteArray())
                    fileOutputStream.flush()
                    fileOutputStream.close()
                    editText.setText("")

                    Toast.makeText(applicationContext, "Data saved successfully", Toast.LENGTH_SHORT).show()

                } catch (e: Exception) {
                    e.printStackTrace()
                }
            } else {
                Toast.makeText(applicationContext, "Data is empty", Toast.LENGTH_SHORT).show()
            }
        }

        display.setOnClickListener {
            try {
                val stringBuffer = StringBuffer()
                var message: String?

                val fileInputStream = FileInputStream(file)
                val inputStreamReader = InputStreamReader(fileInputStream)
                val bufferedReader = BufferedReader(inputStreamReader)

                while (bufferedReader.readLine().also { message = it } != null) {
                    stringBuffer.append(message)
                }

                textView.text = "Message: ${stringBuffer.toString()}"

            } catch (e: Exception) {
                e.printStackTrace()
            }
        }
    }

    private fun isExternalStorageWritable(): Boolean {
        val s = Environment.getExternalStorageState()
        return s != Environment.MEDIA_MOUNTED
    }
}