Intent scanIntent = new Intent("com.google.zxing.client.android.SCAN");
scanIntent.setPackage("com.google.zxing.client.android");

11-11 15:15:27.793: WARN/System.err(15384): android.content.ActivityNotFoundException: No
Activity found to handle Intent { act=com.google.zxing.client.android.SCAN
cat=[android.intent.category.DEFAULT] pkg=com.google.zxing.client.android (has extras) }

<activity android:name="com.google.zxing.client.android.CaptureActivity"
  android:screenOrientation="landscape"
  android:configChanges="orientation|keyboardHidden"
  android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
  android:windowSoftInputMode="stateAlwaysHidden">
  <intent-filter>
    <action android:name="com.google.zxing.client.android.SCAN"/>
    <category android:name="android.intent.category.DEFAULT"/>
  </intent-filter>
</activity>

int REQUEST_SCAN; //Request code for Intent result
String packageString = "com.yourapplication.packagename";

Intent intent = new Intent("com.google.zxing.client.android.SCAN");
intent.setPackage(packageString);
//Add any optional extras to pass
intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
//Launch
startActivityForResult(intent, REQUEST_SCAN);