In this tutorial we learn how to implement QR Code Scanner & Generator using ZXing Scanner & Generator library in Android Application.

A.Add ZXING LiabaryFor Scanning an Generating QR Code.

compile 'com.google.zxing:core:3.2.1'
compile 'com.journeyapps:zxing-android-embedded:3.2.0@aar'

B. Generate QR Code in Android

Step 1 : Select File -> New -> Project -> Android Application Project  create a new project .

 

Step 2 : Open res -> layout -> activity_generate.xml (or) activity_generate.xml and add following code :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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/activity_generate"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimary"
    tools:context="com.example.spider.qrcode.GenerateActivity">

    <LinearLayout
    android:layout_width="match_parent"
    android:background="#ddd"
    android:layout_margin="35dp"
    android:orientation="vertical"
    android:layout_height="match_parent">
    
        <TextView
            android:text="QR Code Generator"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="25dp"
            android:textSize="22dp"
            android:layout_gravity="center"
            android:id="@+id/textView"
            android:layout_alignParentTop="true"
            android:layout_centerHorizontal="true" />

    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_gravity="center"
        android:layout_marginTop="35dp"
        android:padding="10dp"
        android:layout_height="wrap_content">

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:hint="Enter The String"
            android:ems="10"
            android:id="@+id/generate_editText" />

        <Button
        android:text="Generate"
        android:layout_width="wrap_content"
        android:layout_height="40dp"
        android:textColor="#fff"
        android:background="@color/colorPrimary"
        android:id="@+id/button"
     />
    </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:orientation="vertical"
            android:gravity="center"
            android:layout_height="match_parent">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:srcCompat="@mipmap/ic_launcher"
        android:id="@+id/imageView" />
        </LinearLayout>
</LinearLayout>
</LinearLayout>

Step 3 : Open src -> package -> Generate_Activity.java and add following code :

public class GenerateActivity extends AppCompatActivity {

    ImageView qrcodeImageview;
    String QRcode;
    public final static  int WIDTH=300;
    EditText generate_edittxt;
    ImageButton backbutton;
    Button generate_btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_generate);
        generate_edittxt = (EditText) findViewById(R.id.generate_editText);
        generate_btn = (Button) findViewById(R.id.button);
        backbutton=(ImageButton)findViewById(R.id.backbutton);

        backbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(GenerateActivity.this, ReaderActivity.class);
                startActivity(intent);
            }
        });
        qrcodeImageview = (ImageView) findViewById(R.id.imageView);
        generate_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(generate_edittxt.getText().toString().length()==0)
                {
                    Toast.makeText(GenerateActivity.this, "Please Enter The String", Toast.LENGTH_SHORT).show();
                }
                    else
                {
                    Thread t = new Thread(new Runnable() {
                        public void run() {
                            // this is the msg which will be encode in QRcode
                            QRcode=generate_edittxt.getText().toString();



                            try {
                                synchronized (this) {
                                    wait(1000);
                                    // runOnUiThread method used to do UI task in main thread.
                                    runOnUiThread(new Runnable() {
                                        @Override
                                        public void run() {
                                            try {
                                                Bitmap bitmap = null;

                                                bitmap = encodeAsBitmap(QRcode);
                                                qrcodeImageview.setImageBitmap(bitmap);

                                            } catch (WriterException e) {
                                                e.printStackTrace();
                                            } // end of catch block

                                        } // end of run method
                                    });

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



                        }
                    });
                    t.start();

                }

            }
        });

    }

    /*private void getID() {
        qrCodeImageview=(ImageView) findViewById(R.id.img_qr_code_image);
    }
*/
    Bitmap encodeAsBitmap(String str) throws WriterException {
        BitMatrix result;
        try {
            result = new MultiFormatWriter().encode(str,
                    BarcodeFormat.QR_CODE, WIDTH, WIDTH, null);
        }
        catch (IllegalArgumentException iae)
        {
            // Unsupported format
            return null;
        }
        int w = result.getWidth();
        int h = result.getHeight();
        int[] pixels = new int[w * h];
        for (int y = 0; y < h; y++) {
            int offset = y * w;
            for (int x = 0; x < w; x++)
            {
                pixels[offset + x] = result.get(x, y) ? getResources().getColor(R.color.colorAccent):getResources().getColor(R.color.colorPrimary);
            }
        }
        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        bitmap.setPixels(pixels, 0, 300, 0, 0, w, h);
        return bitmap;
    }

}

Step 4 : Open AndroidManifest.xml and add following code :

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

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".ReaderActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

Step 4: Our output will be like this :

C. Scan or Read QR Code in Android

Step 1 : Open res -> layout -> activity_reader.xml add following code :

<?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:id="@+id/activity_reader"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@color/colorPrimary"
    tools:context="com.example.spider.qrcode.ReaderActivity">
<LinearLayout
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_margin="35dp"
    android:background="#ddd"
    android:layout_height="match_parent">
    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="match_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="QR Code Generator An Scanner"
        android:textSize="20dp"
        android:layout_marginTop="50dp"
        android:textStyle="bold"
        android:layout_gravity="center"/>
    <Button
        android:layout_width="175dp"
        android:layout_height="40dp"
        android:text="Generate"
        android:layout_gravity="center"
        android:id="@+id/generate_btnn"
        android:gravity="center"
        android:textColor="#fff"

        android:textSize="18dp"
        android:textStyle="bold"
        android:background="@color/colorPrimary"

        android:layout_marginTop="85dp"
        />
    <Button
        android:layout_width="175dp"
        android:layout_height="40dp"
        android:text="SCAN"
        android:textSize="18dp"
        android:layout_gravity="center"
        android:id="@+id/scan_btn"
        android:gravity="center"
        android:textColor="#fff"
        android:textStyle="bold"
        android:background="@color/colorPrimary"
        android:layout_marginTop="45dp"
        />
    </LinearLayout>
</LinearLayout>
</LinearLayout>

Step 2 : Open src -> package -> ReaderActivity.java and add following code :

public class ReaderActivity extends AppCompatActivity {

    private Button scan_btn;
    private Button generate_btnn;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_reader);
        scan_btn = (Button) findViewById(R.id.scan_btn);
        generate_btnn=(Button)findViewById(R.id.generate_btnn);

        final Activity activity = this;

        generate_btnn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(ReaderActivity.this,GenerateActivity.class);
                startActivity(intent);
            }
        });
        scan_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                IntentIntegrator intentIntegrator = new IntentIntegrator(activity);
                intentIntegrator.setDesiredBarcodeFormats(IntentIntegrator.QR_CODE_TYPES);
                intentIntegrator.setPrompt("SCAN");
                intentIntegrator.setCameraId(0);
                intentIntegrator.setBeepEnabled(false);
                intentIntegrator.setBarcodeImageEnabled(false);
                intentIntegrator.initiateScan();
            }
        });
    }


    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if (result != null) {
            if (result.getContents() == null) {
                Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();
            } else {

                Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();
                System.out.println("SCANNED"+result.getContents());
            }

        }
        else {
            // This is important, otherwise the result will not be passed to the fragment
            super.onActivityResult(requestCode, resultCode, data);
        }
    }
}