Android Studio and android.support.v4.app.Fragment

问题:

I am tryng out Android Studio instead of Eclipse. I install it and then start a completely new project and follow the wizard. I add no code of my own.

Then, I right-click to create a new component, a new Fragment:

and choose a new fragment:

and as soon as I do, I see compile errors:

... so I start googling and find out that I need to install and reference support library 4, and that I do. When I check the build.gradle (whatver that is, new to me coming from Eclipse), I see:

but I change that to

because they said so here. After recompiling and all that, the error is still there. I then reference the .jar-file directly, like this:

and again do recompile yada yada, but that doesnt help either.

This behaviour seems very strange to me. What am I missing here? This is the SDK Manager view:

So, what am I missing? Thanks =)

回答1:

The symptom of this problem is usually that the build works fine from the command line (which means your build.gradle file is set up right) but you get syntax highlighting errors in the IDE. Follow This Steps To Solve The Problem: Click on Tools from the toolbar usually at the top part of your IDE, and then navigate to Android then navigate to Sync Project with Gradle Files button. We realize it's less than ideal that the IDE can't just take care of itself instead of forcing you to manually sync at the right time; we're tracking progress on this in https://code.google.com/p/android/issues/detail?id=63151

回答2:

I have already had the following dependency in my build.gradle

implementation 'com.android.support:support-v13:26.0.2'

I have tried all of the following,

• Invalidate Caches/Restart
• Sync project with gradle files
• Clean project
• Rebuild project
• gradlew clean

But, none of them worked for me.

Finally, I solved it by deleting "/.idea/libraries", and then synced with gradle and built again.

回答3:

Try this may will help you.Go to "File" -> "Invalidate Caches...", and select "Invalidate and Restart" option to fix this.

回答4:

I got the same problem since I updated to latest version of Android Studio 0.3.7. So you can try with my stuffs.

Ensure you have updated to latest version Android Support Repository - 3 Android Support Library - 19

As your attachment picture above, you did it already. Then adding the following setting to your build.gradle

dependencies {
    compile 'com.android.support:support-v4:19.0.0'
}

One more thing: Please make sure your Android SDK is targeting to right SDK folder

回答5:

I found a shortcut: File - Project Structure - Tab:Dependencies Click on the green + sign, select support-v4 (or any other you need), click OK.

now go to your gradle file and see that is been added

回答6:

"File" -> "Invalidate Caches..."

worked for me.

回答7:

1> File -> invalidate caches 2> Build-> Rebuild

its work for me

回答8:

I'm running the most current version of AndroidStudio to date (11/10/2015) -- v1.4 (build AI-141.2288178, built on September 28, 2015) and I built my project and everything worked fine. Then after a few hours of my computer being inactive I came back, edited some code that had nothing to do with the support libraries and started seeing :

cannot resolve symbol 'fragmentactivity' and I was seeing red highlighted items related to fragmentactivity in the AndroidStudio editor.

The solution was to simply do a

Build...Rebuild Project...

I only mention this so others might see it and know it is happening out there.

回答9:

I'm using buck and it seems like by removing the /.idea/libraries in your project folder and sync gradle again works for me.

回答10:

For me : Build->Clean Project solved this question

回答11:

Hrrm... I dont know how many times this has happend so far: I test, try, google, test again and mess around for hours, and when I finally give up, I go to my trusted Stackoverflow and write a detailed and clear question.

When I post the question, switch over to the IDE and boom - error gone.

I can't say why its gone, because I change absolutely nothing in the code except for that I already tried as stated above. But all of a sudden, the compile error is gone!

In the build.gradle, it now says:

dependencies {
    compile "com.android.support:appcompat-v7:18.0.+"
}

which initially did not work, the compile errors did not go away. it took like 30 min before the IDE got it, it seems... hmm...

=== EDIT === When I view the build.gradle again, it has now changed and looks like this:

dependencies {
    compile 'com.android.support:support-v4:18.0.0'
    compile "com.android.support:appcompat-v7:18.0.+"
}

Im not really sure what the appcompat is right now.

回答12:

I found that if you have comments in your build.gradle it may break when you try to add a new support library. So make sure you check your build.gradle and see if it looks alright manually.

回答13:

Complementing the @daylight answer...

goto layout, if your layout don't show, will show a message with

"Tip: build your project"

. So build your project and everything will be fine.

回答14:

To downplay the "magic" of this issue a little bit. You need an Internet connection after you make those changes. If for some reason required libraries cannot by downloaded, instead of giving an appropriate message (like "Failed to fetch libraries") you will simply get the same build error. Was struggling with this for an hour before realizing that my company's VPN blocked the repo.

回答15:

For everyone who comes to this thread and builds with maven: add support-v4 dependency and build to download the repo.

Then add the library manuelly to your project:

Project Structure -> Libraries -> Add

And move to you're repo for the correct jar file: C:\Users\XXXXXXX\.m2\repository\com\google\android\support-v4\r7\support-v4-r7.jar

回答16:

Do sth. modification (just to gradle sync) over app level build.gradle and sync. Again, redo what you changed in build.gradle and sync. It should fix your problem.

回答17:

I was facing the same issue. As it turns out in my build.gradle file there was this :

configurations {
    all*.exclude group: 'com.android.support'
}

Removing that fixed my issue. So guys, if doing all that and still your issue is not fixed, look for any exclude keywords in your gradle file.

回答18:

Android studio has option to manage dependencies. Follow path.

1. Click on File, then select Project Structure
2. Choose Modules "app"
3. Click "Dependencies" tab
4. Click on the + sign, choose Library Dependencies
5. Select support-v4 or other libraries as needed and click OK

FYI check link stackoverflow.com/a/33414287/1280397

回答19:

I encountered this issue and tried everything including File > Invalidate Caches but nothing worked. The reason this issue was happening for me was because I had external projects that were using a different AppCompat version to my main gradle file.

After I updated all gradle files to be the same version the compile error went away.