How to write files to asset folder in android?

This example demonstrates how do I write files to asset folder in 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:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <Button
      android:id="@+id/btnReadFile"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:layout_above="@id/textView"
      android:layout_marginBottom="15dp"
      android:text="Read File"/>
   <TextView
      android:id="@+id/textView"
      android:layout_centerInParent="true"
      android:textSize="16sp"
      android:textStyle="bold|italic"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
</RelativeLayout>

Step 3 – Create a new Assets folder and write a new text file in it.

To write a text file, Right click, select New >> file (Quote.txt)

Step 4 − Add the following code to src/MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
public class MainActivity extends AppCompatActivity {
   TextView textView;
   Button button;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textView = findViewById(R.id.textView);
      button = findViewById(R.id.btnReadFile);
      button.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            String string = "";
            InputStream inputStream = null;
            try {
               inputStream = getAssets().open("Quotes.txt");
               int size = inputStream.available();
               byte[] buffer = new byte[size];
               inputStream.read(buffer);
               string = new String(buffer);
            } catch (IOException e) {
               e.printStackTrace();
            }
            textView.setText(string);
         }
      });
   }
}

Step 5 – Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.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.