How to convert an image file to bytes array in your Android App?

This video shows the code to convert an image file content to byte array in your Android App’s Java code.

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Complete source code and other details:

package com.programmerworld.imagetobytesarray;

import static android.Manifest.permission.READ_MEDIA_IMAGES;

import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.storage.StorageManager;
import android.os.storage.StorageVolume;
import android.view.View;
import android.widget.TextView;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;

public class MainActivity extends AppCompatActivity {

    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_main);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);

            ActivityCompat.requestPermissions(this, new String[]{READ_MEDIA_IMAGES}, PackageManager.PERMISSION_GRANTED);
            textView = findViewById(R.id.textView);
            return insets;
        });
    }

    public void buttonImageToBytes(View view){
        StorageManager storageManager = (StorageManager) getSystemService(STORAGE_SERVICE);
        StorageVolume storageVolume = storageManager.getStorageVolumes().get(0); // 0 internal storage
        File fileImage = new File(storageVolume.getDirectory().getPath() + "/Download/images.jpg");

        try {
            byte[] bytes = Files.readAllBytes(fileImage.toPath());
            textView.setText(String.valueOf(bytes.length));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

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

    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES"/>
    <uses-permission android:name="android.permission.READ_MEDIA_VISUAL_USER_SELECTED"/>


    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.ImageToBytesArray"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.19" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="110dp"
        android:layout_marginTop="42dp"
        android:onClick="buttonImageToBytes"
        android:text="Images to Bytes Array"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Screenshots: