android

android-gradle-plugin

build.gradle

gradle

dependency-management

I'm trying to use the new Android Studio but I can't seem to get it working correctly.

I'm using the Gson library to serialize/deserialize JSON-objects. But the library somehow isn't included in the build.

I had created a new project with just a MainActivity. Copied gson-2.2.3.jar in the /libs folder and added it as a library dependancy(right click->Add as library). This includes the jar in android studio so it can be referenced from the source files.

When I try to run the project it cannot compile so I added:

compile files('libs/gson-2.2.3.jar')

to the dependencies in de .gradle file. After that it compiles correctly but when running the application I get a ClassDefNotFoundException.

Does anyone know what I'm doing wrong?

Solution 1

I've been struggling with the same thing for many hours, trying to get the Gson jar to work no less. I finally cracked it here are the steps I took:

  1. Put the Gson jar (in my case, gson-2.2.4.jar) into the libs folder
  2. Right click it and hit 'Add as library'
  3. Ensure that compile files('libs/gson-2.2.4.jar') is in your build.gradle file (or compile fileTree(dir: 'libs', include: '*.jar') if you are using many jar files)

    Edit : Use implementation files('libs/gson-2.2.4.jar') (or implementation fileTree(dir: 'libs', include: '*.jar')) in Android Studio 3.0+

  4. Do a clean build (you can probably do this fine in Android Studio, but to make sure I navigated in a terminal to the root folder of my app and typed gradlew clean. I'm on Mac OS X, the command might be different on your system

After I did the above four, it started working fine. I think the 'Add as library' step was the one I'd previously missed, and it didn't work until I cleaned it either.

[Edit - added the build.gradle step which is also necessary as others have pointed out]

Solution 2

Here are the instructions for adding a local jar file as a library to a module:

  1. Create a 'libs' folder in the top level of the module directory (the same directory that contains the 'src' directory)

  2. In the build.gradle file add the following so that your dependencies closure has:

    dependencies {
        // ... other dependencies
        compile files('libs/<your jar's name here>')
    }
    
  3. Android Studio should have already setup a gradlew wrapper. From the command line, navigate to the top level of your project (the directory that has a gradlew file).

    Run ./gradlew assemble. This should compile the project with the library. You may need to fix errors in your build.gradle file as necessary.

  4. In order to have Android Studio recognize the local jar files as libraries for support while coding in the IDE, you need to take a few more steps:

    4.1. Right click on the module in the left hand panel and choose Open Library Settings.

    4.2. On the left panel of the dialog, choose Libraries.

    4.3. Click the + sign above the panel second from the left -> Java

    4.4. Select your local jar and add it to the project.

  5. You may need to run the above ./gradlew command one more time

Solution 3

In the project right click

-> new -> module
-> import jar/AAR package
-> import select the jar file to import
-> click ok -> done

Follow the screenshots below:

1:

2:

3:

You will see this:

Solution 4

In Android Stuido, I like use Gradle to manage Gson lib.

Add below dependency in your build.gradle file.

repositories {mavenCentral()}

dependencies {compile 'com.google.code.gson:gson:2.2.4'}

Everything is OK.

You can also see this post. The best way to integrate third party library in Android studio

Solution 5

IIRC, simply using "Add as library" isn't enough for it to compile with the project.

Check Intellij's help about adding libraries to a project

The part that should interest you the most is this:

(In File > Project Structure) Open the module settings and select the Dependencies tab.

On the Dependencies tab, click add and select Library.

In the Choose Libraries dialog, select one or more libraries and click Add Selected.

If the library doesn't show up in the dialog, add it in the Libraries settings, right below Modules.

You shouldn't need to add compile files() anymore, and the library should be properly added to your project.

Solution 6

All these solutions are outdated. It's really easy now in Android Studio:

File > New Module...

The next screen looks weird, like you are selecting some widget or something but keep it on the first picture and below scroll and find "Import JAR or .AAR Package"

Then take Project Structure from File menu.Select app from the opened window then select dependencies ,then press green plus button ,select module dependency then select module you imported then press OK

Solution 7

Easy steps to add external library in Android Studio

  1. If you are in Android View in project explorer, change it to Project view as below

  1. Right click the desired module where you would like to add the external library, then select New > Directroy and name it as 'libs'
  2. Now copy the blah_blah.jar into the 'libs' folder
  3. Right click the blah_blah.jar, Then select 'Add as Library..'. This will automatically add and entry in build.gradle as compile files('libs/blah_blah.jar') and sync the gradle. And you are done

Please Note : If you are using 3rd party libraries then it is better to use dependencies where Gradle script automatically downloads the JAR and the dependency JAR when gradle script run.

Ex : compile 'com.google.android.gms:play-services-ads:9.4.0'

Read more about Gradle Dependency Mangement

Solution 8

'compile files...' used to work for me, but not any more. after much pain, I found that using this instead works:

compile fileTree(dir: 'libs', include: '*.jar')

I have no idea why that made a difference, but, at least the damn thing is working now.

Solution 9

  1. Download Library file from website
  2. Copy from windows explore
  3. Paste to lib folder from Project Explorer
  4. Ctrl+Alt+Shift+S open Project Structure
  5. Select Dependencies Tab, add the file by using +
  6. Tool bar Sync project with gradle file by using button

That solved my problem. Try, if anyone want more details let me know.

Solution 10

I made it work by just adding one line to build.gradle:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar']) ----> AS creates this
    implementation 'com.google.code.gson:gson:2.3.1'   ----------> I added this one
}

Do not forget to click Sync now in the top right corner.

I'm using Android Studio 1.0.1.

Solution 11

I found Dependency Manager of Android Studio quite handy and powerful for managing 3rd party dependencies (like gson mentioned here). Providing step by step guide which worked for me (NOTE: These steps are tested for Android Studio 1.6 and onward versions on Windows platform).

Step-1: Goto "Build > Edit Libraries and Dependencies..." it would open up the dialog "Project Structure"

Step-2: Select "app" and then select "Dependencies" tab. Then select "Add > 1 Library dependency"

Step-3: "Choose Library Dependency" dialog would be shown, specify "gson" in search and press the "search button"

Step-4: The desired dependency would be shown in search list, select com.google.code.gson:gson:2.7 (this is the latest version at the time when I wrote the answer), press OK

Press OK on "Project Structure" dialog. Gradle would update your build scripts accordingly.

Hope this would help :)

Solution 12

1. Put the jar (in my case, gson-2.2.4.jar) into the libs folder.

2. Ensure that compile files (libs/gson-2.2.4.jar) is in your build.gradle file.

3. Now Click on the "Sync Project with Gradle files"(Left to AVD manager Button on the topbar).

After I did the above three, it started working fine.

Solution 13

Download & Copy Your .jar file in libs folder then adding these line to build.gradle:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.google.code.gson:gson:2.3.1'
}

Do not forget to click "Sync now"

Solution 14

You can do this with two options.

first simple way.

Copy the .jar file to clipboard then add it to libs folder. To see libs folder in the project, choose the project from combobox above the folders.

then right click on the .jar file and click add as a library then choose a module then ok. You can see the .jar file in build.gradle file within dependencies block.

 dependencies {
        implementation fileTree(dir: 'libs', include: ['*.jar'])
        implementation 'com.android.support:appcompat-v7:21.0.3'
        implementation project(':okhttp-2.0.0')
        implementation 'com.google.code.gson:gson:2.3.1'
    }

Second way is that: We can add a .jar file to a module by importing this .jar file as a .jar module then add this module to any module we want.

import module ---> choose your .jar file --> than import as a .jar --

Then CTRL+ALT+SHIFT+S --> project sturure -->choose the module you want ato add a jar -->Dependencendies --> Module Dependency. build.gradle of the module will updated automatically.

Solution 15

Ive done above 3 steps and its work charm for me.

(I am using Android Studio 2.1.2)

Step 1

  • Add your jar package name (as an example compile 'com.squareup.okhttp3:okhttp:3.3.1') into gradle build script under build.gradle(Module:app).

Step 2: Right click on app folder -> New -> Module

Step 3: Click Import JAR/.AAR Package Then browse your package. as an example: OkHttp.jar

Solution 16

With Android Studio 3+:

You should just be able to simply copy the jar file to the libs folder right under the app folder.

... myproject\app\libs\myfile.jar

Then select Project Files from the drop-down on the Projects window, right click on the project, select Synchronize to see the file in Project Files. It will automatically add the dependencies in the gradle file (Module:app).

dependencies {
...
    implementation files('libs/myfile.jar')

Here is another solution:

Go to the Project Files view (select Project Files from the dropdown).

Select New... Directory, create a folder named libs right under app.

Open up File Explorer, copy and paste your jar file into the libs folder.

In Android Studio, right click on the jar file, and select Add as a Library... from the popup menu.

You should see the file listed in the dependencies list in the gradle file:

dependencies {
...
    implementation files('libs/myfile.jar')
}

Open up your java file, and add the import statement there:

import com.xxx.xxx;

Solution 17

Put the .jar files in libs folder of the Android project.

Then add this line of code in the app's gradle file:

    compile fileTree(dir: 'libs', include: ['*.jar'])

For Android gradle plugin 3.0 and later, it is better to use this instead:

    implementation fileTree(dir: 'libs', include: ['*.jar'])

Solution 18

Unlike Eclipse we don't need to download jar and put it in /libs folder. Gradle handles these things we only need to add Gradle dependencies, Gradle downloads it and puts in gradle cache.

We need to add dependencies as:

dependencies {implementation 'com.google.code.gson:gson:2.2.4'}

thats it However we can also download jar & add that as library but the best practice is to add Gradle dependencies.

Solution 19

menu File -> project struct -> module select "app" -> dependencies tab -> + button 
-> File dependency -> PATH/myfile.jar

Solution 20

Step 1 : Now under your app folder you should see libs, if you don't see it, then create it .

Step 2 : Drag & Drop the .jar file here, you may be get a prompt "This file does not belong to the project", just click OK Button .

Step 3 : Now you should see the jar file under libs folder, right click on the jar file and select "Add as library", Click OK for prompt "Create Library"

Step 4 : Now this jar has been added.

Solution 21

1) create an 'your_libs' folder inside the Project/app/src folder.

2) Copy your jar file into this 'your_libs' folder

3) In Android Studio, go to File -> Project Structure -> Dependencies -> Add -> File Dependency and navigate to your jar file, which should be under 'src/your_libs'

3) Select your jar file and click 'Ok'

and then you can see on your build.gradle like this : compile files('src/your_libs/your.jar')

Solution 22

In android Studio 1.1.0 . I solved this question by following steps:

1: Put jar file into libs directory. (in Finder)

2: Open module settings , go to Dependencies ,at left-bottom corner there is a plus button. Click plus button then choose "File Dependency" .Here you can see you jar file. Select it and it's resolved.

Solution 23

I have read all the answers here and they all seem to cover old versions of Android Studio!

With a project created with Android Studio 2.2.3 I just needed to create a libs directory under app and place my jar there. I did that with my file manager, no need to click or edit anything in Android Studio.

Why it works? Open Build / Edit Libraries and Dependencies and you will see:

{include=[*.jar], dir=libs}

Solution 24

In your project-name/app folder, find the libs folder. If there is no libs folder, create one. Add your .jar file. Right-click on it and you will find add .jar as a dependency. You can find the dependencies added to your build.gradle file.

Solution 25

On Mac OS X:

  1. Add jar as library (drag jar to libs, right click add as lib)

  2. Add compile statement to build.grade

  3. Install gradle v1.6 (use homebrew)

    • brew install gradle
    • gradle -v
    • if not v1.6, upgrade homebrew
  4. gradle clean (rebuild android did not work)

This sorted me out.

Solution 26

My answer is basically gathering some of the right but incomplete answers provided above.

  1. Open build.gradle
  2. Add the following:

    dependencies {
    compile 'com.android.support:appcompat-v7:19.+'
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.google.code.gson:gson:2.3'
    }
    

    This will allow support for two different ways of adding dependencies. The compile fileTree(dir: 'libs', include: ['*.jar']) (as @Binod mentioned) tells the compiler to look under the folder libs for ANY jar. It is a good practice to create such a folder 'libs' which will contain the jar packages that our application needs to use.

But this will also allow support for Maven dependency. The compile 'com.google.code.gson:gson:2.3' (as mentioned by @saneryee) it is another recommended way to add dependencies that are in a central remote repository and not in our /libs "local repository". It is basically telling gradle to look for that version of that package and it's telling the compiler to consider it when compiling the project (having it in the classpath)

PS: I use both

Solution 27

Like many before pointed out you shall add

compile files('libs/gson-2.2.3.jar') 

to your build.gradle file.

However I have a project in Android Studio that was migrated from Eclipse and in this case the "libs" folder is named "lib" so for me removing the "s" solved the problem.

Solution 28

  1. Added the libs folder at the level of app.
  2. Added all the jars in this project.
  3. Next, selected all the jars, in the libs folder,
  4. right click on the selected items, and say add library
  5. then you will find the jars expansion option, within the project explorer itself.

I observed CTRL + ALT + SHIFT + S --> project structure --> app-module -->Dependencies" already had an entry as (dir: 'libs', include: '*.jar') under compile-option, initially. And after adding the jar's as per the steps stated above, the build.gradle got the entries for the new added jar's, itself.

Solution 29

In Android Studio 2.1 I follow the this way,

Goto app -> src-> main -> assets folder (If not available create it) -> put your JAR files

In your build.gradle add dependency like this,

implementation files('src/main/assets/jsoup.jar')
implementation files('src/main/assets/org-apache-xmlrpc.jar')
implementation files('src/main/assets/org.apache.commons.httpclient.jar')
implementation files('src/main/assets/ws-commons-util-1.0.2.jar')

Sync now. Now your JAR files ready to use.

Solution 30

For newer Android 1.0.2 the following is already there in your build.gradle file

implementation fileTree(include: ['*.jar'], dir: 'libs')

Add the library jar to your libs folder -> right click the library -> click add as a library -> it asks you for the project to add it for -> select your project-> click ok The following line is automatically added to build.gradle

implementation files('libs/android-query.jar')

That did it for me. nothing more was required. i have shown this for android aquery another third party library for android.