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遷移主原文：https://blog.csdn.net/dandelionela/article/details/102976961 # 【AS-AndroidX】AndroidX的遷移 #
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問題1：使用自動遷移時報錯
那麼就需要去每一個報錯的類裏面，參照類對照表，逐一把未替換的support類及自動替換錯的類修正成AndroidX的類
需要注意的是，IDE的build日誌只輸出100個錯誤，雖然寫的是100個，其實後邊還有很多。改完這100還有下一個100，加油！
問題2：百度地圖SDK
報錯：java.lang.UnsatisfiedLinkError: No implementation found for int com.baidu.mapsdkplatform.comjni.tools.JNITools.initClass
2019-11-12 11:55:59.209 23040-23040/? E/libc: Access denied finding property "ro.vendor.df.effect.conflict"
2019-11-12 11:55:59.223 23040-23040/? E/NativeLoader: found libBaiduMapSDK_base_v5_4_4.so error
2019-11-12 11:55:59.223 23040-23040/? E/.***.****: No implementation found for int com.baidu.mapsdkplatform.comjni.tools.JNITools.initClass(java.lang.Object, int) (tried Java_com_baidu_mapsdkplatform_comjni_tools_JNITools_initClass and Java_com_baidu_mapsdkplatform_comjni_tools_JNITools_initClass__Ljava_lang_Object_2I)
2019-11-12 11:55:59.224 23040-23040/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.*****.***.******, PID: 23040
java.lang.UnsatisfiedLinkError: No implementation found for int com.baidu.mapsdkplatform.comjni.tools.JNITools.initClass(java.lang.Object, int) (tried Java_com_baidu_mapsdkplatform_comjni_tools_JNITools_initClass and Java_com_baidu_mapsdkplatform_comjni_tools_JNITools_initClass__Ljava_lang_Object_2I)
at com.baidu.mapsdkplatform.comjni.tools.JNITools.initClass(Native Method)
at com.baidu.mapsdkplatform.comjni.tools.a.b(Unknown Source:6)
at com.baidu.mapsdkplatform.comapi.a.<clinit>(Unknown Source:23)
at com.baidu.mapsdkplatform.comapi.a.a(Unknown Source:0)
at com.baidu.mapsdkplatform.comapi.c.a(Unknown Source:17)
at com.baidu.mapapi.SDKInitializer.initialize(Unknown Source:2)
at com.dandelionela.metro.elametro.MetroApplication.initializeBaiduMap(MyApplication.java:61)
at com.dandelionela.metro.elametro.MetroApplication.onCreate(MyApplication.java:53)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1183)
...
第一步嘗試去百度地圖官方API文檔找些資料，沒有找到，所以就先升級了一下百度地圖到V6.0.0仍然報錯。
於是將jniLibs文件夾下的ndk支持庫從單獨的【armeabi-v7a】改爲單獨的【arm64-v8a】發現報錯消失。
很奇怪，在升級AndroidX之前同一手機使用armeabi-v7a可以正常使用，升級完AndroidX之後，就不行了。也是奇怪。
問題3：
2019-11-12 13:43:19.118 27256-27256/com.***.*** E/libc: Access denied finding property "ro.vendor.df.effect.conflict"
2019-11-12 13:43:19.136 27256-27295/com.***.*** E/Perf: Fail to get file list lib
2019-11-12 13:43:19.136 27256-27295/com.***.*** E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2019-11-12 13:43:19.137 27256-27295/com.***.*** E/Perf: Fail to get file list ***.***.***.***
2019-11-12 13:43:19.137 27256-27295/com.***.*** E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2019-11-12 13:43:19.216 27256-27256/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.***.***, PID: 27256
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.***.***/com.***.***.activity.WelcomeActivity}: android.view.InflateException: Binary XML file line #2 in com.***.***:layout/activity_welcome: Binary XML file line #2 in com.***.***/activity_welcome: Error inflating class androidx.constraintlayout.ConstraintLayout
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3304)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3443)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2040)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7520)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: android.view.InflateException: Binary XML file line #2 in com.***.***:layout/activity_welcome: Binary XML file line #2 in com.***.***:layout/activity_welcome: Error inflating class androidx.constraintlayout.ConstraintLayout
Caused by: android.view.InflateException: Binary XML file line #2 in com.***.***:layout/activity_welcome: Error inflating class androidx.constraintlayout.ConstraintLayout
Caused by: java.lang.ClassNotFoundException: androidx.constraintlayout.ConstraintLayout
at java.lang.Class.classForName(Native Method)
at java.lang.Class.forName(Class.java:454)
at android.view.LayoutInflater.createView(LayoutInflater.java:819)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:1010)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:965)
at android.view.LayoutInflater.inflate(LayoutInflater.java:663)
at android.view.LayoutInflater.inflate(LayoutInflater.java:538)
at android.view.LayoutInflater.inflate(LayoutInflater.java:481)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
at com.***.***.activity.WelcomeActivity.onCreate(WelcomeActivity.java:31)
at android.app.Activity.performCreate(Activity.java:7894)
at android.app.Activity.performCreate(Activity.java:7881)
突然找到了問題的關鍵所在：
androidx.constraintlayout.ConstraintLayout
這個類路徑有誤！這是由IDE自動轉化爲AndroidX的時候自動生成的。顯然是錯誤的。我們只改了Java文件中的導包錯誤，卻忽略了XML文件中的類的錯誤。
打開看一下源碼：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
... />
</androidx.constraintlayout.ConstraintLayout>
果然是ConstraintLayout標籤的包名不對。按照對照表，把錯誤的【androidx.constraintlayout.ConstraintLayout】修改爲【androidx.constraintlayout.widget.ConstraintLayout】
然後全局檢索一下錯誤的AndroidX替換，改爲正確的AndroidX替換。幾十處，擦。。。。。
同樣的問題還發生在其他IDE導包錯誤的地方：
Caused by: java.lang.ClassNotFoundException: android.support.design.widget.TabLayout
Caused by: java.lang.ClassNotFoundException: androidx.core.view.ViewPager
Caused by: java.lang.ClassNotFoundException: android.support.v7.widget.RecyclerView
Caused by: java.lang.ClassNotFoundException: android.support.design.widget.FloatingActionButton
Caused by: java.lang.ClassNotFoundException: android.support.v4.widget.SwipeRefreshLayout
Caused by: java.lang.ClassNotFoundException: androidx.core.widget.SwipeRefreshLayout
Caused by: java.lang.ClassNotFoundException: androidx.core.widget.DrawerLayout
Caused by: java.lang.ClassNotFoundException: android.support.design.widget.CoordinatorLayout
Caused by: java.lang.ClassNotFoundException: android.support.design.widget.AppBarLayout
Caused by: java.lang.ClassNotFoundException: android.support.design.widget.NavigationView
Caused by: java.lang.ClassNotFoundException: android.support.constraint.Guideline
XML佈局文件中需要修改的常用控件：
| Support Library Class | AndroidX Class |
| android.support.constraint.ConstraintLayout | androidx.constraintlayout.widget.ConstraintLayout |
| android.support.design.widget.FloatingActionButton | com.google.android.material.floatingactionbutton.FloatingActionButton |
| android.support.design.widget.AppBarLayout | com.google.android.material.appbar.AppBarLayout |
| android.support.v7.widget.RecyclerView | androidx.recyclerview.widget.RecyclerView |
| android.support.design.widget.CoordinatorLayout | androidx.coordinatorlayout.widget.CoordinatorLayout |
| android.support.v7.widget.Toolbar | androidx.appcompat.widget.Toolbar |
| android.support.v4.widget.SwipeRefreshLayout | androidx.swiperefreshlayout.widget.SwipeRefreshLayout |
| android.support.design.widget.TabLayout | com.google.android.material.tabs.TabLayout |
| android.support.v4.view.ViewPager | androidx.viewpager.widget.ViewPager |
| android.support.v4.widget.DrawerLayout | androidx.drawerlayout.widget.DrawerLayout |
| android.support.design.widget.NavigationView | com.google.android.material.navigation.NavigationView |
| android.support.v7.widget.SwitchCompat | androidx.appcompat.widget.SwitchCompat |
| android.support.design.widget.CollapsingToolbarLayout | com.google.android.material.appbar.CollapsingToolbarLayout |
| android.support.v7.widget.CardView | androidx.cardview.widget.CardView |
容易被Android Studio 識別錯誤的控件：
| Wrong AndroidX Class by IDE | Correct AndroidX Class |
| androidx.constraintlayout.ConstraintLayout | androidx.constraintlayout.widget.ConstraintLayout |
| androidx.core.widget.SwipeRefreshLayout | androidx.swiperefreshlayout.widget.SwipeRefreshLayout |
| androidx.core.view.ViewPager | androidx.viewpager.widget.ViewPager |
| androidx.core.widget.DrawerLayout | androidx.drawerlayout.widget.DrawerLayout |