支持：CardView最低SDK？

Question

I'm trying to add CardView support into my app for devices lower than Android L by adding the line:

compile 'com.android.support:cardview-v7:21.+'

I've then added compileSdkVersion and targetSdkVersion to 'android-L'

Now, unless I am mistaken, I thought that this would have built on my Nexus 5 in 4.4.4, however I get the error

Failure [INSTALL_FAILED_OLDER_SDK]

Am I missing something or misunderstood this? Full build.gradle below:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 'android-L'
    buildToolsVersion "20.0.0"

    defaultConfig {
        applicationId "com.gh.app"
        minSdkVersion 15
        targetSdkVersion 'android-L'
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            runProguard false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    wearApp project(':wear')
    compile 'com.google.android.gms:play-services-wearable:+'
    compile 'com.android.support:support-v4:20.0+'
    compile files('libs/TalkClient.jar')
    compile 'com.android.support:cardview-v7:21.+'
}

Answer 1

虽然CardView和RecyclerView都是添加到支持库的新窗口小部件 （因此将在API 7+设备上可用），但在开发人员预览期间，它们仅限于Android L设备。