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API Version Incompatibilities

API Version Incompatibilities
I have made an app using android studio, until now I have been testing it on a 'Nexus 5X (API 23) emulator'. However, today i started debugging the app on a 'Samsung Galaxy Tab 2 7.0 (API 18)' and the app will not even start. I know this is because of incompatibilities between the API's specifically something to do with the Theme i'm using. What i want to know is how i can fix this problem without changing the look of the app drastically.
Log Cat Crash Log
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.***.********/com.***.********.MenuActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.access$700(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:175)
at android.app.ActivityThread.main(ActivityThread.java:5279)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
at android.support.v7.app.AppCompatDelegateImplBase.onCreate(AppCompatDelegateImplBase.java:124)
at android.support.v7.app.AppCompatDelegateImplV7.onCreate(AppCompatDelegateImplV7.java:146)
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:59)
at com.***.*******.MenuActivity.onCreate(MenuActivity.java:47)
at android.app.Activity.performCreate(Activity.java:5283)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295) 
at android.app.ActivityThread.access$700(ActivityThread.java:150) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:175) 
at android.app.ActivityThread.main(ActivityThread.java:5279) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869) 
at dalvik.system.NativeStart.main(Native Method) 
Android Manifest
<?xml version="1.0" encoding="utf-8"?>
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity
android:name=".MenuActivity"
android:label="#string/app_name"
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".About" />
<activity android:name=".SettingsActivity" />
<activity android:name=".********Activity" />
<activity android:name=".********Activity" />
<activity
android:name=".VideoPlayerActivity"
android:screenOrientation="landscape" />
<activity android:name=".*******Activity"></activity>
</application>
Gradle Build App File
apply plugin: 'com.android.application'
android {
compileSdkVersion 21
buildToolsVersion "23.0.3"
defaultConfig {
applicationId "com.***.*******"
minSdkVersion 15
targetSdkVersion 22
versionCode 1
versionName "2.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:22.2.1'
compile 'com.android.support:design:22.2.1'
}
Note: The last two lines (the ones with compile...) are underlined in red and say 'This support library should not use a different version(22) than the compile SDK version(21).'
Edit: If I change the Theme for the main activity to '#style/Theme.AppCompat.NoActionBar' the application will start however, the look of the application changes. Also, other activities that do not use the new theme work fine.
Any Help is Appreciated.

Google Play Services 7.5.0 AnalyticsService NPE onStartCommand

Has anyone run into this crash when loading Google Play 7.5.0 in their app? I'm seeing about 30 crashes a day now, without any way to reproduce. No particular Android flavour (4.4, 5, 5.1) or device (Samsung, HTC, etc..) is sticking out at me.
java.lang.RuntimeException: Unable to start service com.google.android.gms.analytics.AnalyticsService#1153b3b0 with null: java.lang.NullPointerException
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2721)
at android.app.ActivityThread.access$1900(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1353)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5116)
at java.lang.reflect.Method.invokeNative(Method.java)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(NativeStart.java)
Caused by: java.lang.NullPointerException
at com.google.android.gms.analytics.AnalyticsService.onStartCommand()
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2704)
at android.app.ActivityThread.access$1900(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1353)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5116)
at java.lang.reflect.Method.invokeNative(Method.java)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(NativeStart.java)
This issue has also been posted on the Analytics bug tracker, but I don't expect to see any movement there for a while: https://code.google.com/p/analytics-issues/issues/detail?id=667
Here is what is in my Gradle file:
compile 'com.google.android.gms:play-services:7.5.0'
And in my AndroidManifest (which I think is verbatim from the Google docs):
<receiver
android:name="com.google.android.gms.analytics.AnalyticsReceiver"
android:enabled="true" >
<intent-filter>
<action android:name="com.google.android.gms.analytics.ANALYTICS_DISPATCH" />
</intent-filter>
</receiver>
<service
android:name="com.google.android.gms.analytics.AnalyticsService"
android:enabled="true"
android:exported="false" />

Try with the latest Google play services SDK version. It has been fixed in Google Play services 9.2.1.

NotificationListenerService with RemoteController.OnClientUpdateListener crashes on API18 (4.3)

The Problem
I want to implement the new RemoteController API, which has been introduced with API19 (Kitkat,4.4). The API requires me to implement a class which extends from NotificationListenerService (introduced with API18) and implements the RemoteController.OnClientUpdateListener interface. (Further information on how to implement all this can be found here and a very helpful example project can be found here)
Everything's working as it should on my API19 (Kitkat,4.4) device and every other API<18 device. However the problem is, that the app crashes right away on API18 (Jelly bean, 4.3), because the "android.service.notification.NotificationListenerService" is being sent and starts my RemoteService, which then crashes the app instantly with the following Stacktrace:
05-24 09:32:48.945 893-893/com.example E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate service com.example.RemoteService: java.lang.ClassNotFoundException: Didn't find class "com.example.RemoteService" on path: DexPathList[[zip file "/data/app/com.example-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example-1, /system/lib]]
at android.app.ActivityThread.handleCreateService(ActivityThread.java:2561)
at android.app.ActivityThread.access$1600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1338)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.RemoteService" on path: DexPathList[[zip file "/data/app/com.example-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example-1, /system/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.ActivityThread.handleCreateService(ActivityThread.java:2558)
at android.app.ActivityThread.access$1600(ActivityThread.java:141
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1338)
...
This is caused by the simple fact, that RemoteController and therefore the implemented interface RemoteController.OnClientUpdateListener is not available on API18, but NotificationListenerService is. The intent is not being sent on every device
What I've tried so far
Put another layer of abstraction on it and build a simple "if (API>=19)" check.
I tried to do this by using a second empty NotificationListenerService which would just work as a kind of callthrough Service. I would put that second Service in my AndroidManifest, so that it receives the intent instead, and then I'd just put the "if (API>=19)" check in its onCreate and start my actual RemoteService from there. The result is, that my App doesn't crash any more (yay). Unfortunately it also doesn't work in API19 Kitkat any more :(. I think that's because I have to register my RemoteService as a listener in my AndroidManifest directly, or otherwise it won't receive anything.
Code snippets
RemoteService.java:
public class RemoteService extends NotificationListenerService
implements RemoteController.OnClientUpdateListener {
...
}
AndroidManifest.xml:
<manifest ...>
<application ...>
<service android:name="com.example.RemoteService"
android:label="#string/app_name"
android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE">
<intent-filter>
<action android:name="android.service.notification.NotificationListenerService" />
</intent-filter>
</service>
</application>
</manifest>

The solution
Put a bool in an xml file in values and values-v19. Set it to false in values and to true in values-v19. Now set the NotificationListenerService's "android:enabled" tag to this bool.
./values/bool_switches.xml:
<resources>
<bool name="remotecontrollerservice_enabled">false</bool>
</resources>
./values-v19/bool_switches.xml:
<resources>
<bool name="remotecontrollerservice_enabled">true</bool>
</resources>
./AndroidManifest.xml:
...
<service android:name=".services.RemoteControllerService"
android:label="#string/scrobblingservice_string"
android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE"
android:enabled="#bool/remotecontrollerservice_enabled">
<intent-filter>
<action android:name="android.service.notification.NotificationListenerService"/>
</intent-filter>
</service>
...

Just disable the service with android:enabled="false", then in Application.onCreate enable it if the device is running KitKat or newer.

Android ClassNotFoundException: Didn't find class on path

I can't find the solution of this error. Can you please give the permanent solution? I have no idea how to solve it.
01-04 11:06:42.302: E/AndroidRuntime(1906): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{e.gochat/e.gochat.gochat.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "e.gochat.gochat.MainActivity" on path: DexPathList[[zip file "/data/app/e.gochat-1.apk"],nativeLibraryDirectories=[/data/app-lib/e.gochat-1, /vendor/lib, /system/lib]]
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread.access$700(ActivityThread.java:135)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.os.Handler.dispatchMessage(Handler.java:102)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.os.Looper.loop(Looper.java:137)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread.main(ActivityThread.java:4998)
01-04 11:06:42.302: E/AndroidRuntime(1906): at java.lang.reflect.Method.invokeNative(Native Method)
01-04 11:06:42.302: E/AndroidRuntime(1906): at java.lang.reflect.Method.invoke(Method.java:515)
01-04 11:06:42.302: E/AndroidRuntime(1906): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
01-04 11:06:42.302: E/AndroidRuntime(1906): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
01-04 11:06:42.302: E/AndroidRuntime(1906): at dalvik.system.NativeStart.main(Native Method)
01-04 11:06:42.302: E/AndroidRuntime(1906): Caused by: java.lang.ClassNotFoundException: Didn't find class "e.gochat.gochat.MainActivity" on path: DexPathList[[zip file "/data/app/e.gochat-1.apk"],nativeLibraryDirectories=[/data/app-lib/e.gochat-1, /vendor/lib, /system/lib]]
01-04 11:06:42.302: E/AndroidRuntime(1906): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
01-04 11:06:42.302: E/AndroidRuntime(1906): at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
01-04 11:06:42.302: E/AndroidRuntime(1906): at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
01-04 11:06:42.302: E/AndroidRuntime(1906): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
01-04 11:06:42.302: E/AndroidRuntime(1906): ... 11 more
01-04 11:07:06.772: I/Process(1906): Sending signal. PID: 1906 SIG: 9
This is my app Manifest XML
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="e.gochat"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="9"
android:targetSdkVersion="18" />
<permission
android:name="e.gochat.permission.C2D_MESSAGE"
android:protectionLevel="signature" />
<uses-permission android:name="e.gochat.permission.C2D_MESSAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<application
android:name="e.gochat.Common"
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="e.gochat.MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="e.gochat.ChatActivity"
/>
<activity
android:name="e.gochat.SettingsActivity"
android:label="#string/title_activity_settings" />
<receiver
android:name="e.gochat.client.GcmBroadcastReceiver"
android:permission="com.google.android.c2dm.permission.SEND" >
<intent-filter>
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
<category android:name="e.gochat" />
</intent-filter>
</receiver>
<provider
android:name="e.gochat.DataProvider"
android:authorities="e.gochat.provider"
android:exported="false">
</provider>
</application>
I'm not sure what's wrong here. I've added the .jar file in the java build path. And yet I'm getting this classnotfound exception. The app loads when I import the android.app.Application

I have solved this problem by disabling the instant run option of android studio.
To disable Instant Run Goto
File -> Settings
-> Build,Execution, Deployment -> Instant Run -> Uncheck the checkbox for instant run

I don't know for sure what is your package name, but if it is e.gochat do this.
Add package="e.gochat" to manifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="e.gochat"
.....
.....
>
On each activity declaration for android:name put a dot before activity name:
<activity
android:name=".MainActivity">
............
</activity>
<activity
android:name=".ChatActivity">
EDIT
After your edited I can see e.gochat is your package name.
Now you only need to remove e.gochat from each activity/provider/receiver name as I said in second part of my answer.
Android will add that for you.

Using Android Studio
After upgrading to Android Stuido 0.8.2, I had this problem. I tried a lot of things, including
Clean project
Clean project (gradle clean)
Invalidate Caches and Restart
De-qualify the Activity Name in AndroidManifest.xml (.MyActivity)
Nothing worked until I re-imported the entire project.
File -> Close Project -> Import Project... -> Choose the same project -> OK
This fixed it for me

Uninstalling the app in the device and running the project again fixed it for me.

The reason why this was affecting me was due to an incorrect path name in a layout file
<android.support.v4.app.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.app.view.ViewPager>
The correct absolute path of ViewPager is
android.support.v4.view.ViewPager
After correcting the path it worked. I did not have to prefix the activity name with a '.'.

For me, this was occurring on devices running < Android 5.0 because I didn't have multidex support enabled (this is, over 65k total methods incl. libs). Multidex is automatic and native on Android 5.0+ (specifically, devices using ART).

The problem was solved by removing MultiDexSupport from build.gradle file :
defaultConfig {
multiDexEnabled true // This line was causing above problem
}
Removing the MultiDexSupport solved the problem

This issue has multiple answers based on the different scenario.
I was getting the same error when using a library(.aar) in my Android Studio project.
The root cause in my case was that I missed to add a third party lib dependency in app's build.gradle file which was being used by the .aar file.
e.g:- The library(.aar) was using 'com.squareup.okhttp3:okhttp:3.4.1'. So I had to add
compile 'com.squareup.okhttp3:okhttp:3.4.1'
in the app's build.gradle. Hope it helps someone.

ANDROID STUDIO
In addittion to Kishor's answer:
The error occured on my small project when I enabled multiDexEnabled = true in the gradle defaultconfig.
Using the generated .apk file crashes on start of the app with the known error message.
For me it was solved when I built the .apk file via gradle (right side of android studio) -> "yourapp" -> Tasks- > install -> installDebug
Hope this helps someone with this strange error

I implemented a listener that was not available in the android version I was running yet and this led to the same error.
Example MainActivity:
// RecyclerView.OnScrollChangeListener is only available on API >= 23
public class MainActivity implements RecyclerView.OnScrollChangeListener
{
}
Running this activity on a device with API < 23 will result in this error as well...

If you tried other solitions and none of them work. Sometimes this error happen because some library use Java 8 features. To solve the problem, configure Android Gradle Plugin to support Java 8 by adding the following code to your build.gradle file
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}

For me the issue occurred as I wasn't including the kotlin-android and kotlin-android-extensions plugins in my :app modules build.gradle.
E.g.
plugins {
id 'com.android.application'
id 'kotlin-android'
id 'kotlin-android-extensions'
}
Or if you're using the Kotlin DSL
plugins {
id("com.android.application")
kotlin("android")
kotlin("android.extensions")
}

dependencies {
implementation 'androidx.appcompat:appcompat:+'
implementation 'androidx.constraintlayout:constraintlayout:+'
}
Remove this line from Gradle

Integrate ZXing in Android Studio

I'll start explaining all the steps I have done and in the end what is the problem.
Download ZXing-2.2 https://code.google.com/p/zxing/downloads/list
Extrac all in zxing-2.2.
Download and install Apache Ant http://www.youtube.com/watch?v=XJmndRfb1TU
With the use of Windows Commandline (Run->CMD) navigate to the extracted directory
In the commandline window - Type 'ant -f core/build.xml' press enter and let Apache work it's magic
At this moment is like Integrating the ZXing library directly into my Android application
But Wooops, "Buildfile: core\build.xml does not exists! Build failed. ok.
6. Importing ZXing - missing core/build.xml
Now yes, i have my core.jar.
Open Android Studio, File -> Import Project -> Select /android/ in /zxing-2.2/ -> Create project from existing sources -> Project name: andoid -> Source files for... all checked Next -> Libraries (cant do nothing) Next -> Modules (android checked) Next -> SDK 1.7 Next -> Finish
With Project Open -> Build -> Rebuild project
100 errors
19 warnings
File -> project Structure -> Libraries -> Add -> Java -> Select core.jar that i create before and OK -> Library 'core' will be added to the selected modules. (android) OK -> And OK in the Project Structure Dialog.
Build -> Rebuild Project
15 errors
20 warnings
All errors are error: constant expression required and
I see Error in Switch cases of ZXing project in android
I change all switchs for if elses.
0 errors
20 warnings
Ok, now continue:
File -> New project -> zxing_demo Next -> Next -> Blank Activity Next -> Finish
In new project -> File -> Import module -> Search and select /android/ OK -> Create module from existing sources Next -> Next -> Next -> Next -> Finish
Now I can see in the explorer /android/ /zging_demoProject/ and External Libraries
Now i change my code tu scan QR
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.zxing_demo"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="16" />
<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera" />
<uses-feature
android:name="android.hardware.camera.autofocus"
android:required="false" />
<uses-feature
android:name="android.hardware.touchscreen"
android:required="false" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.zxing_demo.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:clearTaskOnLaunch="true"
android:stateNotNeeded="true"
android:configChanges="orientation|keyboardHidden"
android:name="com.google.zxing.client.android.CaptureActivity"
android:screenOrientation="landscape"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"
android:windowSoftInputMode="stateAlwaysHidden" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
<intent-filter >
<action android:name="com.google.zxing.client.android.SCAN" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
MainActivity.java
package com.example.zxing_demo;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = new Intent("com.google.zxing.client.android.SCAN");
intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
startActivityForResult(intent, 0);
}
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
if (requestCode == 0) {
if (resultCode == RESULT_OK) {
String contents = intent.getStringExtra("SCAN_RESULT");
String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
// Handle successful scan
} else if (resultCode == RESULT_CANCELED) {
// Handle cancel
}
}
}
}
Now test, Run -> Debug
And CRASH.
Logcat
08-31 02:58:28.085 20665-20665/com.example.zxing_demo E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.zxing_demo/com.google.zxing.client.android.CaptureActivity}: java.lang.ClassNotFoundException: com.google.zxing.client.android.CaptureActivity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1891)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
at android.app.ActivityThread.access$600(ActivityThread.java:127)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4448)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: com.google.zxing.client.android.CaptureActivity
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1882)
... 11 more
I can see in AndroidManifest.xml in this line
android:name="com.google.zxing.client.android.CaptureActivity"
"CaptureActivity" in red and the error say: Cannot resolve symbol 'CaptureActivity'
File -> Project Structure -> Modules -> zxing_demo -> Dependencies -> Add -> Module dependency -> android OK -> Apply and OK
Now CaptureActivity looks good
Debug again
08-31 03:06:58.513 21740-21740/com.example.zxing_demo E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.zxing_demo/com.google.zxing.client.android.CaptureActivity}: java.lang.ClassNotFoundException: com.google.zxing.client.android.CaptureActivity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1891)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
at android.app.ActivityThread.access$600(ActivityThread.java:127)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4448)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: com.google.zxing.client.android.CaptureActivity
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1882)
... 11 more
I think I will use the application and intents, but now I want do this work, if someone now whats happen tell me please.

I was integrating ZXING into an Android application and there were no good sources for the input all over, I will give you a hint on what worked for me - because it turned out to be very easy.
There is a real handy git repository that provides the zxing android library project as an AAR archive.
https://github.com/journeyapps/zxing-android-embedded
All you have to do is add this to your build.gradle
repositories {
jcenter()
}
dependencies {
implementation 'com.journeyapps:zxing-android-embedded:3.0.2#aar'
implementation 'com.google.zxing:core:3.2.0'
}
and Gradle does all the magic to compile the code and makes it accessible in your app.
To start the Scanner afterwards, use this class/method:
From the Activity:
new IntentIntegrator(this).initiateScan(); // `this` is the current Activity
From a Fragment:
IntentIntegrator.forFragment(this).initiateScan(); // `this` is the current Fragment
// If you're using the support library, use IntentIntegrator.forSupportFragment(this) instead.
There are several customizing options:
IntentIntegrator integrator = new IntentIntegrator(this);
integrator.setDesiredBarcodeFormats(IntentIntegrator.ONE_D_CODE_TYPES);
integrator.setPrompt("Scan a barcode");
integrator.setCameraId(0); // Use a specific camera of the device
integrator.setBeepEnabled(false);
integrator.setBarcodeImageEnabled(true);
integrator.initiateScan();
They have a sample-project and are providing several integration examples:
AnyOrientationCaptureActivity
ContinuousCaptureActivity
CustomScannerActivity
ToolbarCaptureActivity
If you already visited the link you going to see that I just copy&pasted the code from the git README. If not, go there to get some more insight and code examples.

Anybody facing the same issues, follow the simple steps:
Import the project android from downloaded zxing-master zip file using option Import project (Eclipse ADT, Gradle, etc.) and add the dollowing 2 lines of codes in your app level build.gradle file and and you are ready to run.
So simple, yahh...
dependencies {
// https://mvnrepository.com/artifact/com.google.zxing/core
compile group: 'com.google.zxing', name: 'core', version: '3.2.1'
// https://mvnrepository.com/artifact/com.google.zxing/android-core
compile group: 'com.google.zxing', name: 'android-core', version: '3.2.0'
}
You can always find latest version core and android core from below links:
https://mvnrepository.com/artifact/com.google.zxing/core/3.2.1
https://mvnrepository.com/artifact/com.google.zxing/android-core/3.2.0
UPDATE (29.05.2019)
Add these dependencies instead:
dependencies {
implementation 'com.google.zxing:core:3.4.0'
implementation 'com.google.zxing:android-core:3.3.0'
}

buttion.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new com.google.zxing.integration.android.IntentIntegrator(Fragment.this).initiateScan();
}
});
public void onActivityResult(int requestCode, int resultCode, Intent data) {
IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
if(result != null) {
if(result.getContents() == null) {
Log.d("MainActivity", "Cancelled scan");
Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();
} else {
Log.d("MainActivity", "Scanned");
Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();
}
} else {
// This is important, otherwise the result will not be passed to the fragment
super.onActivityResult(requestCode, resultCode, data);
}
}
dependencies {
compile 'com.journeyapps:zxing-android-embedded:3.2.0#aar'
compile 'com.google.zxing:core:3.2.1'
compile 'com.android.support:appcompat-v7:23.1.0'
}

From version 4.x, only Android SDK 24+ is supported by default, and androidx is required.
Add the following to your build.gradle file:
repositories {
jcenter()
}
dependencies {
implementation 'com.journeyapps:zxing-android-embedded:4.1.0'
implementation 'androidx.appcompat:appcompat:1.0.2'
}
android {
buildToolsVersion '28.0.3' // Older versions may give compile errors
}
Older SDK versions
For Android SDK versions < 24, you can downgrade zxing:core to 3.3.0 or earlier for Android 14+ support:
repositories {
jcenter()
}
dependencies {
implementation('com.journeyapps:zxing-android-embedded:4.1.0') { transitive = false }
implementation 'androidx.appcompat:appcompat:1.0.2'
implementation 'com.google.zxing:core:3.3.0'
}
android {
buildToolsVersion '28.0.3'
}
You'll also need this in your Android manifest:
<uses-sdk tools:overrideLibrary="com.google.zxing.client.android" />
Source : https://github.com/journeyapps/zxing-android-embedded

this tutorial help me to integrate to android studio:
http://wahidgazzah.olympe.in/integrating-zxing-in-your-android-app-as-standalone-scanner/
if down try THIS
just add to AndroidManifest.xml
<activity
android:name="com.google.zxing.client.android.CaptureActivity"
android:configChanges="orientation|keyboardHidden"
android:screenOrientation="landscape"
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>
Hope this help!.