使用新的 android 导航组件运行启用 proguard 的构建时，找不到我的片段类。我收到这个堆栈跟踪：
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.myapppackage.path, PID: 24334
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapppackage.path/com.myapppackage.path.MainActivity}: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #10: Error inflating class fragment
Caused by: java.lang.RuntimeException: Exception inflating com.myapppackage.path:navigation/nav_graph line 7
at androidx.navigation.h.a(Unknown Source:124)
at androidx.navigation.c.a(Unknown Source:4)
at androidx.navigation.fragment.NavHostFragment.a(Unknown Source:88)
at android.support.v4.app.g.k(Unknown Source:15)
at android.support.v4.app.m.a(Unknown Source:382)
at android.support.v4.app.m.b(Unknown Source:7)
at android.support.v4.app.m.a(Unknown Source:74)
at android.support.v4.app.m.onCreateView(Unknown Source:216)
at android.support.v4.app.j.a(Unknown Source:4)
at android.support.v4.app.h.a(Unknown Source:2)
at android.support.v4.app.e.onCreateView(Unknown Source:0)
at android.support.v4.app.h.onCreateView(Unknown Source:0)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.j.b(Unknown Source:23)
at android.support.v7.app.c.setContentView(Unknown Source:4)
at com.myapppackage.path.MainActivity.onCreate(Unknown Source:6)
at android.app.Activity.performCreate(Activity.java:6999)
at android.app.Activity.performCreate(Activity.java:6990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.myapppackage.path.ui.start.StartFragment
at androidx.navigation.fragment.a$a.a(Unknown Source:58)
at androidx.navigation.fragment.a$a.a(Unknown Source:19)
at androidx.navigation.h.a(Unknown Source:16)
at androidx.navigation.h.a(Unknown Source:133)
at androidx.navigation.h.a(Unknown Source:31)
at androidx.navigation.c.a(Unknown Source:4)
at androidx.navigation.fragment.NavHostFragment.a(Unknown Source:88)
at android.support.v4.app.g.k(Unknown Source:15)
at android.support.v4.app.m.a(Unknown Source:382)
at android.support.v4.app.m.b(Unknown Source:7)
at android.support.v4.app.m.a(Unknown Source:74)
at android.support.v4.app.m.onCreateView(Unknown Source:216)
at android.support.v4.app.j.a(Unknown Source:4)
at android.support.v4.app.h.a(Unknown Source:2)
at android.support.v4.app.e.onCreateView(Unknown Source:0)
at android.support.v4.app.h.onCreateView(Unknown Source:0)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.j.b(Unknown Source:23)
at android.support.v7.app.c.setContentView(Unknown Source:4)
at com.myapppackage.path.MainActivity.onCreate(Unknown Source:6)
at android.app.Activity.performCreate(Activity.java:6999)
at android.app.Activity.performCreate(Activity.java:6990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.ClassNotFoundException: com.myapppackage.path.ui.start.StartFragment
at java.lang.Class.classForName(Native Method)
at java.lang.Class.forName(Class.java:453)
E/AndroidRuntime: at androidx.navigation.fragment.a$a.a(Unknown Source:45)
... 38 more
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.myapppackage.path.ui.start.StartFragment" on path: DexPathList[[zip file "/data/app/com.myapppackage.path-yqk9eOoCoeyT3xg78oYcxg==/base.apk"],nativeLibraryDirectories=[/data/app/com.myapppackage.path-yqk9eOoCoeyT3xg78oYcxg==/lib/arm64, /system/lib64, /vendor/lib64]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:125)
at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
... 41 more
它说它找不到在我的nav_graph.xml文件中定义的片段类：
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.myapppackage.path.ui.start.StartFragment
我的nav_graph.xml：
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
app:startDestination="@id/start">
<fragment
android:id="@+id/start"
android:name="com.myapppackage.path.ui.start.StartFragment"
android:label="start_fragment"
tools:layout="@layout/start_fragment" />
</navigation>
如您所见，在xml中设置了片段的名称，该路径在运行proguard后似乎变得无效。
到目前为止，我唯一的解决方法是-keepnames在我的proguard-rules.pro文件中定义我的每个片段类路径。例如：
-keepnames class com.myapppackage.path.ui.start.StartFragment
在此之后，混淆编译运行良好而不会崩溃。
虽然我不确定这是否正确，但我做错了吗？我们如何在不为 proguard 规则中的每个片段定义规则的情况下将新的导航架构组件与我们的混淆构建一起使用？
我知道这个问题现在可能只是一个问题，因为导航片段组件仍处于 alpha 阶段。