How to create text file and insert data to that file on Android?

This example demonstrates how to create text file and insert data to that file on Android.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentLeft="true"
      android:layout_alignParentRight="true"
      android:background="#008080"
      android:padding="5dp"
      android:text="Android Write Text to a File"
      android:textColor="#fff" />
   <EditText
      android:id="@+id/editText1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentLeft="true"
      android:layout_alignParentRight="true"
      android:layout_below="@+id/textView1"
      android:layout_marginTop="22dp"
      android:ems="10"
      android:layout_margin="5dp">
      <requestFocus />
   </EditText>
   <Button
      android:id="@+id/button1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentLeft="true"
      android:layout_alignParentRight="true"
      android:layout_below="@+id/editText1"
      android:text="Write Text into File"
      android:onClick="WriteBtn"
      android:layout_margin="5dp"/>
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.java
package com.example.sample;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import android.app.Activity;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
   EditText textmsg;
   static final int READ_BLOCK_SIZE=100;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textmsg=(EditText)findViewById(R.id.editText1);
   }
   // write text to file
   public void WriteBtn(View v) {
      // add-write text into file
      try {
         FileOutputStream fileout=openFileOutput("mytextfile.txt", MODE_PRIVATE);
         OutputStreamWriter outputWriter=new OutputStreamWriter(fileout);
         outputWriter.write(textmsg.getText().toString());
         outputWriter.close();
         //display file saved message
         Toast.makeText(getBaseContext(), "File saved successfully!",
         Toast.LENGTH_SHORT).show();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}
Step 4 − Add the following code to manifests/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.sample">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run   icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −
Click here to download the project code