Simple Scanning Barcode/QR code by Android Phone

Every Android mobile device, has the ability to read QR codes as well as scanning barcodes by using it's own Camera. In this example, we are going to learn how the Android Barcode/Qr Code Scanner is implemented via the use of the ZXing library, which will help us to carry out barcode scanning within an application. We will call on the resources in this open apk library within our app, retrieving and processing the returned results.
First, design a layout for activity:

activity_scan.xml

<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=".ScanActivity">

    <Button
        android:id="@+id/btn_scan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_margin="10dp"
        android:text="@string/scan" />

    <TextView
        android:id="@+id/format"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btn_scan"
        android:gravity="center"
        android:textColor="@android:color/holo_blue_dark"
        android:textSize="20sp" />

    <TextView
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/format"
        android:gravity="center"
        android:textColor="@android:color/holo_green_dark"
        android:textSize="20sp" />

</RelativeLayout>

After click "Scan Barcode or QR code" button, our app will invoke Scan Activity of Barcode Scanner application (if you haven't install it, app will open GooglePlay to get it). Code for button event:

private View.OnClickListener onClickListener() {
        return new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    Intent intent = new Intent("com.google.zxing.client.android.SCAN");
                    startActivityForResult(intent, 0);
                } catch (ActivityNotFoundException ex) {
                    ex.printStackTrace();

                    //if you haven't install barcodeScanner app, download it from Google Play
                    downloadScanBarcode();
                }

            }
        };
    }

After complete scanning code, retrieving back data in onActivityResult() method:

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 0) {
            if (resultCode == RESULT_OK) {
                format.setText(data.getStringExtra("SCAN_RESULT_FORMAT"));
                content.setText(data.getStringExtra("SCAN_RESULT"));
            } else if (resultCode == RESULT_CANCELED) {
                format.setText("Press a button to start a scan.");
                content.setText("Scan cancelled.");
            }
        }
    }

And this is method which open GooglePlay to download Barcode Scanner app:

    /**
     * Go to GooglePlay Store and down load "ScanBarCode" app
     */
    private void downloadScanBarcode() {
        Uri uri = Uri.parse("market://search?q=pname:" + "com.google.zxing.client.android");
        Intent intent = new Intent(Intent.ACTION_VIEW, uri);
        try {
            startActivity(intent);
        } catch (ActivityNotFoundException ex) {
            ex.printStackTrace();
        }
    }

Full ScanActivity.java code:

package com.blogspot.hongthaiit.barcode;

import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class ScanActivity extends Activity {

    private View btnScan;
    private TextView content;
    private TextView format;

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

        btnScan = (View) findViewById(R.id.btn_scan);
        content = (TextView) findViewById(R.id.content);
        format = (TextView) findViewById(R.id.format);

        btnScan.setOnClickListener(onClickListener());
    }

    private View.OnClickListener onClickListener() {
        return new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    Intent intent = new Intent("com.google.zxing.client.android.SCAN");
                    startActivityForResult(intent, 0);
                } catch (ActivityNotFoundException ex) {
                    ex.printStackTrace();

                    //if you haven't install barcodeScanner app, download it from Google Play
                    downloadScanBarcode();
                }

            }
        };
    }

    /**
     * Go to GooglePlay Store and down load "ScanBarCode" app
     */
    private void downloadScanBarcode() {
        Uri uri = Uri.parse("market://search?q=pname:" + "com.google.zxing.client.android");
        Intent intent = new Intent(Intent.ACTION_VIEW, uri);
        try {
            startActivity(intent);
        } catch (ActivityNotFoundException ex) {
            ex.printStackTrace();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 0) {
            if (resultCode == RESULT_OK) {
                format.setText(data.getStringExtra("SCAN_RESULT_FORMAT"));
                content.setText(data.getStringExtra("SCAN_RESULT"));
            } else if (resultCode == RESULT_CANCELED) {
                format.setText("Press a button to start a scan.");
                content.setText("Scan cancelled.");
            }
        }
    }
}

Some screenshots after running (click for full size):