突然发现好多安卓项目已经改为了AndroidX，那么自己的项目也该升级一下了。下面是AndroidX的官方文档的概述。
AndroidX概述
AndroidX是Android团队用于在Jetpack中开发，测试，打包，版本和发布库的开源项目 。
AndroidX是对原始Android 支持库的重大改进 。与支持库一样，AndroidX与Android操作系统分开提供，并提供跨Android版本的向后兼容性。AndroidX通过提供功能奇偶校验和新库完全取代了支持库。此外，AndroidX还包括以下功能：
AndroidX中的所有软件包都以字符串开头，位于一致的命名空间中androidx。支持库包已映射到相应的androidx.*包中。
与支持库不同，AndroidX软件包是单独维护和更新的。这些androidx包使用 从版本1.0.0开始的严格语义版本控制。您可以单独更新项目中的AndroidX库。
所有新的支持库开发都将在AndroidX库中进行。这包括维护原始支持库工件和引入新的Jetpack组件。
1、修改project目录下 gradle.properties，在里面添加两行代码：
# 表示使用 androidx
android.useAndroidX=true
# 表示将第三方库迁移到 androidx
android.enableJetifier=true2、点击菜单项中的Refactor中的Migratet to AndroidX。然后点击窗口右上角的sync Now。（adnroid studio版本必须在3.3及以上）
3、按理说这样就可以了，但是我改了之后发现项目一片报红，上网搜了下发现需要修改引用包，都需要改为AndroidX的包，下面是我遇到的几个错误：
a、AndroidManifest.xml中的application中的activity全部报红，解决方法：修改activity引用的包为：
import androidx.appcompat.app.AppCompatActivity然后再app的build.gradle中的android中添加以下代码：
lintOptions {
disable 'GoogleAppIndexingWarning'
}b、剩下的还是各种包导入错误，之前的v4、v7包全部不能用了，都需要改。
c、布局文件也一定要改，比如ViewPager由android.support.v4.view.ViewPager改为了androidx.viewpager.widget.ViewPager；CardView由android.support.v7.widget.CardView改为了androidx.cardview.widget.CardView；RecycleView由android.support.v7.widget.RecycleView改为了com.scwang.smartrefresh.layout.SmartRefreshLayout；FloatingActionButton也改为了com.google.android.material.floatingactionbutton.FloatingActionButton。
这只是一部分，下面的是官网上的介绍：
| Old build artifact | AndroidX build artifact |
|---|---|
android.arch.core:common |
androidx.arch.core:core-common:2.0.0-rc01 |
android.arch.core:core |
androidx.arch.core:core:2.0.0-rc01 |
android.arch.core:core-testing |
androidx.arch.core:core-testing:2.0.0-rc01 |
android.arch.core:runtime |
androidx.arch.core:core-runtime:2.0.0-rc01 |
android.arch.lifecycle:common |
androidx.lifecycle:lifecycle-common:2.0.0-rc01 |
android.arch.lifecycle:common-java8 |
androidx.lifecycle:lifecycle-common-java8:2.0.0-rc01 |
android.arch.lifecycle:compiler |
androidx.lifecycle:lifecycle-compiler:2.0.0-rc01 |
android.arch.lifecycle:extensions |
androidx.lifecycle:lifecycle-extensions:2.0.0-rc01 |
android.arch.lifecycle:livedata |
androidx.lifecycle:lifecycle-livedata:2.0.0-rc01 |
android.arch.lifecycle:livedata-core |
androidx.lifecycle:lifecycle-livedata-core:2.0.0-rc01 |
android.arch.lifecycle:reactivestreams |
androidx.lifecycle:lifecycle-reactivestreams:2.0.0-rc01 |
android.arch.lifecycle:runtime |
androidx.lifecycle:lifecycle-runtime:2.0.0-rc01 |
android.arch.lifecycle:viewmodel |
androidx.lifecycle:lifecycle-viewmodel:2.0.0-rc01 |
android.arch.paging:common |
androidx.paging:paging-common:2.0.0-rc01 |
android.arch.paging:runtime |
androidx.paging:paging-runtime:2.0.0-rc01 |
android.arch.paging:rxjava2 |
androidx.paging:paging-rxjava2:2.0.0-rc01 |
android.arch.persistence.room:common |
androidx.room:room-common:2.0.0-rc01 |
android.arch.persistence.room:compiler |
androidx.room:room-compiler:2.0.0-rc01 |
android.arch.persistence.room:guava |
androidx.room:room-guava:2.0.0-rc01 |
android.arch.persistence.room:migration |
androidx.room:room-migration:2.0.0-rc01 |
android.arch.persistence.room:runtime |
androidx.room:room-runtime:2.0.0-rc01 |
android.arch.persistence.room:rxjava2 |
androidx.room:room-rxjava2:2.0.0-rc01 |
android.arch.persistence.room:testing |
androidx.room:room-testing:2.0.0-rc01 |
android.arch.persistence:db |
androidx.sqlite:sqlite:2.0.0-rc01 |
android.arch.persistence:db-framework |
androidx.sqlite:sqlite-framework:2.0.0-rc01 |
com.android.support.constraint:constraint-layout |
androidx.constraintlayout:constraintlayout:1.1.2 |
com.android.support.constraint:constraint-layout-solver |
androidx.constraintlayout:constraintlayout-solver:1.1.2 |
com.android.support.test.espresso.idling:idling-concurrent |
androidx.test.espresso.idling:idling-concurrent:3.1.0 |
com.android.support.test.espresso.idling:idling-net |
androidx.test.espresso.idling:idling-net:3.1.0 |
com.android.support.test.espresso:espresso-accessibility |
androidx.test.espresso:espresso-accessibility:3.1.0 |
com.android.support.test.espresso:espresso-contrib |
androidx.test.espresso:espresso-contrib:3.1.0 |
com.android.support.test.espresso:espresso-core |
androidx.test.espresso:espresso-core:3.1.0 |
com.android.support.test.espresso:espresso-idling-resource |
androidx.test.espresso:espresso-idling-resource:3.1.0 |
com.android.support.test.espresso:espresso-intents |
androidx.test.espresso:espresso-intents:3.1.0 |
com.android.support.test.espresso:espresso-remote |
androidx.test.espresso:espresso-remote:3.1.0 |
com.android.support.test.espresso:espresso-web |
androidx.test.espresso:espresso-web:3.1.0 |
com.android.support.test.janktesthelper:janktesthelper |
androidx.test.jank:janktesthelper:1.0.1 |
com.android.support.test.services:test-services |
androidx.test:test-services:1.1.0 |
com.android.support.test.uiautomator:uiautomator |
androidx.test.uiautomator:uiautomator:2.2.0 |
com.android.support.test:monitor |
androidx.test:monitor:1.1.0 |
com.android.support.test:orchestrator |
androidx.test:orchestrator:1.1.0 |
com.android.support.test:rules |
androidx.test:rules:1.1.0 |
com.android.support.test:runner |
androidx.test:runner:1.1.0 |
com.android.support:animated-vector-drawable |
androidx.vectordrawable:vectordrawable-animated:1.0.0 |
com.android.support:appcompat-v7 |
androidx.appcompat:appcompat:1.0.0 |
com.android.support:asynclayoutinflater |
androidx.asynclayoutinflater:asynclayoutinflater:1.0.0 |
com.android.support:car |
androidx.car:car:1.0.0-alpha5 |
com.android.support:cardview-v7 |
androidx.cardview:cardview:1.0.0 |
com.android.support:collections |
androidx.collection:collection:1.0.0 |
com.android.support:coordinatorlayout |
androidx.coordinatorlayout:coordinatorlayout:1.0.0 |
com.android.support:cursoradapter |
androidx.cursoradapter:cursoradapter:1.0.0 |
com.android.support:customtabs |
androidx.browser:browser:1.0.0 |
com.android.support:customview |
androidx.customview:customview:1.0.0 |
com.android.support:design |
com.google.android.material:material:1.0.0-rc01 |
com.android.support:documentfile |
androidx.documentfile:documentfile:1.0.0 |
com.android.support:drawerlayout |
androidx.drawerlayout:drawerlayout:1.0.0 |
com.android.support:exifinterface |
androidx.exifinterface:exifinterface:1.0.0 |
com.android.support:gridlayout-v7 |
androidx.gridlayout:gridlayout:1.0.0 |
com.android.support:heifwriter |
androidx.heifwriter:heifwriter:1.0.0 |
com.android.support:interpolator |
androidx.interpolator:interpolator:1.0.0 |
com.android.support:leanback-v17 |
androidx.leanback:leanback:1.0.0 |
com.android.support:loader |
androidx.loader:loader:1.0.0 |
com.android.support:localbroadcastmanager |
androidx.localbroadcastmanager:localbroadcastmanager:1.0.0 |
com.android.support:media2 |
androidx.media2:media2:1.0.0-alpha03 |
com.android.support:media2-exoplayer |
androidx.media2:media2-exoplayer:1.0.0-alpha01 |
com.android.support:mediarouter-v7 |
androidx.mediarouter:mediarouter:1.0.0 |
com.android.support:multidex |
androidx.multidex:multidex:2.0.0 |
com.android.support:multidex-instrumentation |
androidx.multidex:multidex-instrumentation:2.0.0 |
com.android.support:palette-v7 |
androidx.palette:palette:1.0.0 |
com.android.support:percent |
androidx.percentlayout:percentlayout:1.0.0 |
com.android.support:preference-leanback-v17 |
androidx.leanback:leanback-preference:1.0.0 |
com.android.support:preference-v14 |
androidx.legacy:legacy-preference-v14:1.0.0 |
com.android.support:preference-v7 |
androidx.preference:preference:1.0.0 |
com.android.support:print |
androidx.print:print:1.0.0 |
com.android.support:recommendation |
androidx.recommendation:recommendation:1.0.0 |
com.android.support:recyclerview-selection |
androidx.recyclerview:recyclerview-selection:1.0.0 |
com.android.support:recyclerview-v7 |
androidx.recyclerview:recyclerview:1.0.0 |
com.android.support:slices-builders |
androidx.slice:slice-builders:1.0.0 |
com.android.support:slices-core |
androidx.slice:slice-core:1.0.0 |
com.android.support:slices-view |
androidx.slice:slice-view:1.0.0 |
com.android.support:slidingpanelayout |
androidx.slidingpanelayout:slidingpanelayout:1.0.0 |
com.android.support:support-annotations |
androidx.annotation:annotation:1.0.0 |
com.android.support:support-compat |
androidx.core:core:1.0.0 |
com.android.support:support-content |
androidx.contentpager:contentpager:1.0.0 |
com.android.support:support-core-ui |
androidx.legacy:legacy-support-core-ui:1.0.0 |
com.android.support:support-core-utils |
androidx.legacy:legacy-support-core-utils:1.0.0 |
com.android.support:support-dynamic-animation |
androidx.dynamicanimation:dynamicanimation:1.0.0 |
com.android.support:support-emoji |
androidx.emoji:emoji:1.0.0 |
com.android.support:support-emoji-appcompat |
androidx.emoji:emoji-appcompat:1.0.0 |
com.android.support:support-emoji-bundled |
androidx.emoji:emoji-bundled:1.0.0 |
com.android.support:support-fragment |
androidx.fragment:fragment:1.0.0 |
com.android.support:support-media-compat |
androidx.media:media:1.0.0 |
com.android.support:support-tv-provider |
androidx.tvprovider:tvprovider:1.0.0 |
com.android.support:support-v13 |
androidx.legacy:legacy-support-v13:1.0.0 |
com.android.support:support-v4 |
androidx.legacy:legacy-support-v4:1.0.0 |
com.android.support:support-vector-drawable |
androidx.vectordrawable:vectordrawable:1.0.0 |
com.android.support:swiperefreshlayout |
androidx.swiperefreshlayout:swiperefreshlayout:1.0.0 |
com.android.support:textclassifier |
androidx.textclassifier:textclassifier:1.0.0 |
com.android.support:transition |
androidx.transition:transition:1.0.0 |
com.android.support:versionedparcelable |
androidx.versionedparcelable:versionedparcelable:1.0.0 |
com.android.support:viewpager |
androidx.viewpager:viewpager:1.0.0 |
com.android.support:wear |
androidx.wear:wear:1.0.0 |
com.android.support:webkit |
androidx.webkit:webkit:1.0.0 |
