Android QR Code / Bar Code Scanner

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Android QR Code / Bar Code Scanner

During the development of an android application, sometimes it is required to provide a functionality that scans a QR code or barcode. Scanning the QR code can be done programmatically by using many ways:

Using a web-based API solution, where the QR code or barcode is uploaded to the server, and the server returns the results.
Using a web-based application that accesses your camera and scans the QR code or barcode and returns the results.
By Integrating the Mobile Vision API of Google Play Service.

Android QR Code Scanner Example

In this example, we will scan the QR code of a web URL and Email address, and act on it. Here we will use the Mobile Vision API of Google Play Service to scan the QR code. The Mobile Vision API supports the following formats of the barcode.

1D barcodes: EAN-8, UPC-A, EAN-13, EAN-8, UPC-E, Code-93, Code-128, Code-39, Codabar, ITF.
2D barcodes: QR Code, Data Matrix, AZTEC, PDF-417.

Create an activity_main.xml and add the following code.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="example.TheDeveloperBlog.com.qrcodebarcodescanner.MainActivity">

    <Button
        android:id="@+id/btnScanBarcode"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="44dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="@string/scan_barcode"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.676"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

Create an activity_scanned_barcode.xml layout and add the following code. The SurfaceView widget is used for camera source.

activity_scanned_barcode.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"
    android:padding="@dimen/activity_horizontal_margin">

    <SurfaceView
        android:id="@+id/surfaceView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/btnAction"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_centerVertical="true" />

    <TextView
        android:id="@+id/txtBarcodeValue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:layout_marginStart="@dimen/activity_horizontal_margin"
        android:text="No Barcode Detected"
        android:textColor="@android:color/white"
        android:textSize="20sp" />


    <Button
        android:id="@+id/btnAction"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="ADD CONTENT IN THE MAIL" />
</RelativeLayout>

Create an activity_email.xml layout to perform email action.

activity_email.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="example.TheDeveloperBlog.com.qrcodebarcodescanner.EmailActivity">

    <Button
        android:id="@+id/btnSendEmail"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/inBody"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="64dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="@string/send_email"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />


    <TextView
        android:id="@+id/txtEmailAddress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="Email Address: "
        android:textSize="16dp"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/inSubject"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/inSubject"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtEmailAddress"
        android:layout_centerHorizontal="true"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="88dp"
        android:ems="10"
        android:hint="Subject"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/inBody"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/inSubject"
        android:layout_centerHorizontal="true"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="164dp"
        android:ems="10"
        android:hint="Body"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

Add the Google Mobile Vision API in build.gradle file.

build.gradle

implementation of 'com.google.android.gms:play-services-vision:11.8.0'

In the MainActivity.java file, add the following code. By clicking the button btnScanBarcode it call the ScannedBarcodeActivity.java class.

MainActivity.java

package example.TheDeveloperBlog.com.qrcodebarcodescanner;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    Button  btnScanBarcode;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnScanBarcode = findViewById(R.id.btnScanBarcode);

        btnScanBarcode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivity(new Intent(MainActivity.this, ScannedBarcodeActivity.class));
            }
        });
    }
}

In the ScannedBarcodeActivity.java activity class, add the following code. This class scans the QR code through the camera. In this class, we will generate two QR code, one for web URL and another is for an email address. A QR code can be generated from any of QR code generator website.

ScannedBarcodeActivity.java

package example.TheDeveloperBlog.com.qrcodebarcodescanner;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;
import java.io.IOException;

public class ScannedBarcodeActivity extends AppCompatActivity {


    SurfaceView surfaceView;
    TextView txtBarcodeValue;
    private BarcodeDetector barcodeDetector;
    private CameraSource cameraSource;
    private static final int REQUEST_CAMERA_PERMISSION = 201;
    Button btnAction;
    String intentData = "";
    boolean isEmail = false;

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

    private void initViews() {
        txtBarcodeValue = findViewById(R.id.txtBarcodeValue);
        surfaceView = findViewById(R.id.surfaceView);
        btnAction = findViewById(R.id.btnAction);
        btnAction.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (intentData.length() > 0) {
                    if (isEmail)
                        startActivity(new Intent(ScannedBarcodeActivity.this, EmailActivity.class).putExtra("email_address", intentData));
                    else {
                        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(intentData)));
                    }
                }
            }
        });
    }

    private void initialiseDetectorsAndSources() {

        Toast.makeText(getApplicationContext(), "Barcode scanner started", Toast.LENGTH_SHORT).show();
        barcodeDetector = new BarcodeDetector.Builder(this)
                .setBarcodeFormats(Barcode.ALL_FORMATS)
                .build();

        cameraSource = new CameraSource.Builder(this, barcodeDetector)
                .setRequestedPreviewSize(1920, 1080)
                .setAutoFocusEnabled(true) //you should add this feature
                .build();

        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    if (ActivityCompat.checkSelfPermission(ScannedBarcodeActivity.this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
                        cameraSource.start(surfaceView.getHolder());
                    } else {
                        ActivityCompat.requestPermissions(ScannedBarcodeActivity.this, new
                                String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
                    }

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

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });


        barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
            @Override
            public void release() {
                Toast.makeText(getApplicationContext(), "To prevent memory leaks barcode scanner has been stopped", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> barcodes = detections.getDetectedItems();
                if (barcodes.size() != 0) {
                    txtBarcodeValue.post(new Runnable() {
                        @Override
                        public void run() {

                            if (barcodes.valueAt(0).email != null) {
                                txtBarcodeValue.removeCallbacks(null);
                                intentData = barcodes.valueAt(0).email.address;
                                txtBarcodeValue.setText(intentData);
                                isEmail = true;
                                btnAction.setText("ADD CONTENT TO THE MAIL");
                            } else {
                                isEmail = false;
                                btnAction.setText("LAUNCH URL");
                                intentData = barcodes.valueAt(0).displayValue;
                                txtBarcodeValue.setText(intentData);
                            }
                        }
                    });
                }
            }
        });
    }


    @Override
    protected void onPause() {
        super.onPause();
        cameraSource.release();
    }

    @Override
    protected void onResume() {
        super.onResume();
        initialiseDetectorsAndSources();
    }
}

In the EmailActivity.java class, add the following code. This class performs the email sending task to the address mention in the QR code.

EmailActivity.java

package example.TheDeveloperBlog.com.qrcodebarcodescanner;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class EmailActivity extends AppCompatActivity implements View.OnClickListener {

    EditText inSubject, inBody;
    TextView txtEmailAddress;
    Button btnSendEmail;

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

    private void initViews() {
        inSubject = findViewById(R.id.inSubject);
        inBody = findViewById(R.id.inBody);
        txtEmailAddress = findViewById(R.id.txtEmailAddress);
        btnSendEmail = findViewById(R.id.btnSendEmail);

        if (getIntent().getStringExtra("email_address") != null) {
            txtEmailAddress.setText("Recipient : " + getIntent().getStringExtra("email_address"));
        }

        btnSendEmail.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(Intent.ACTION_SEND);
                intent.setType("text/plain");
                intent.putExtra(Intent.EXTRA_EMAIL, new String[]{txtEmailAddress.getText().toString()});
                intent.putExtra(Intent.EXTRA_SUBJECT, inSubject.getText().toString().trim());
                intent.putExtra(Intent.EXTRA_TEXT, inBody.getText().toString().trim());

                startActivity(Intent.createChooser(intent, "Send Email"));
            }
        });
    }

    @Override
    public void onClick(View v) {

        switch (v.getId()) {
            case R.id.btnScanBarcode:
                startActivity(new Intent(EmailActivity.this, ScannedBarcodeActivity.class));
                break;
        }
    }
}

Add the following code in AndroidMenifest.xml file.

AndroidMenifest.java

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

    <uses-feature
        android:name="android.hardware.camera"
        android:required="true" />

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET" />

    <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>

        <activity android:name=".ScannedBarcodeActivity" />
        <activity
            android:name=".EmailActivity"
            android:windowSoftInputMode="adjustPan" />
    </application>

</manifest>

Output:

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TheDeveloperBlog.com

Android QR Code / Bar Code Scanner

Android QR Code / Bar Code Scanner

Android QR Code Scanner Example

activity_main.xml

activity_scanned_barcode.xml

activity_email.xml

build.gradle

MainActivity.java

ScannedBarcodeActivity.java

EmailActivity.java

AndroidMenifest.java

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