Cannot resolve symbol '?attr/actionBarSize'

问题:

After updating Android Studio from 2.3 to 3.0 I changed buildToolsVersion from 26.0.0 to 26.0.2 and after then I am getting this error:

Cannot resolve symbol '?attr/actionBarSize

Xml code:

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:background="@color/colorPrimary"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
    app:titleTextColor="@android:color/white"/>

Dependencies:

compile 'com.android.support:appcompat-v7:26.1.0'
compile 'com.android.support:design:26.1.0'

回答1:

Nothing helped, but changing:

?attr/actionBarSize to ?android:attr/actionBarSize did the job.

That's actually a bug in few versions. Even if you won't fix it, Android will automatically fix it at runtime.

回答2:

Update all your library versions to 26.1.0 (to the most recent version) and also add:

compile 'com.android.support:support-v4:26.1.0'

if you are using Android Studio 3.0.0 and above then use

implementation 'com.android.support:support-v4:26.1.0'

Sync your project and the error will automatically resolve because ?attr/actionBarSize is part of v4 library.

回答3:

In the project directory hierarchy switch "Android" to "Project". Then delete a folder ".idea/libraries", only "libraries". Select an option from the menu "File -> Invalidate Caches / Restart... -> Invalidate and Restart".

回答4:

Good day, I know this is a bit late.

but I have encountered this one too, when I updated to Android Studio 3.0

what i did is I changed

compile 'com.android.support:support-v4:26.1.0'

to

implementation 'com.android.support:support-v4:26.1.0'

Hope it can help somebody.

回答5:

This is what I did to fix exactly the same problem. 1. Go to SDK manager. 2. Check Android API 27 and Android 8.0 (Oreo) 3. Click "Apply" to download and install those SDKs 4. In build.gradle, change the 'buildToolsVersion "26.0.1"' to 'buildToolsVersion "26.0.2"' and do a gradle sync.

Hope this can help fix your issue.

回答6:

Your buildToolsVersion version differs from version in dependencies (e.g. buildToolsVersion is 27.0.0 but implementation 'com.android.support:support-v4:27.0.1'). Make them the same.

回答7:

Try to add this in your build.gradle(app) dependencies:

resolutionStrategy {
    force libraries.support.appCompat
    force libraries.support.design
    force 'com.android.support:support-utils:26.0.1'
    force 'com.android.support:support-compat:26.0.1'
}

回答8:

my problem solved by changing compileSdkVersion and targetSdkVersion from 26 to the last version 27, also u need to upgrade ur dependencies to 27.

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com......"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.0'
    implementation 'com.android.support:design:27.1.0'
}

hope this solve ur problem too :)

回答9:

This worked.

I have updated the compile and support lib versions from 26.x.x to 27.x.x.

回答10:

I tried all the answers here and so many others from lots of places but only the below techniques worked for me. The simple way is you just need to close the project then import the same project as a Gradle project Or you can go to Project structure -> project -> change Gradel plugin = 4.4 and Android plugin version = 3.1.4. Both of these above methods work.

Note: These versions(4.4, 3.1.4) are latest when I write this answer please use the latest version instead of these.

回答11:

Maybe you hava upgraded the version of gradle. when my gradle version is 4.4 and plugin version is 3.1.1.It is ok.

回答12:

this work:

delete all file in $HOME/.gradle/caches/transforms-1/files-1.1/appcompat-v7-27.1.1.aar

回答13:

Changed all Support Library versions to the newest 27.1.1 and the error was gone.

回答14:

please replace android support libraries.

from

27.1.1

to

28.0.0-alpha3

and replace 27 to 28 for following cases:

compileSdkVersion 28
buildToolsVersion "28.0.0"
targetSdkVersion 28

this will fix the issue.