context.getSystemService（UserManager.class）在装有华为手机的Android 9上返回null

Question

有人知道运行Android 9的华为手机的问题吗？尝试访问时，它总是返回null：

context.getSystemService(UserManager.class)

问题是很多API都依赖它，就像androidx.core中的UserManagerCompat一样：

public static boolean isUserUnlocked(@NonNull Context context) {
    if (Build.VERSION.SDK_INT >= 24) {
        return context.getSystemService(UserManager.class).isUserUnlocked();
    } else {
        return true;
    }
}

导致：：>>

java.lang.RuntimeException: 
  at android.app.ActivityThread.handleBindApplication (ActivityThread.java:6737)
  at android.app.ActivityThread.access$2000 (ActivityThread.java:273)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:2020)
  at android.os.Handler.dispatchMessage (Handler.java:112)
  at android.os.Looper.loop (Looper.java:216)
  at android.app.ActivityThread.main (ActivityThread.java:7625)
  at java.lang.reflect.Method.invoke (Method.java)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:524)
  at com.android.internal.os.WebViewZygoteInit.main (WebViewZygoteInit.java:171)
  at java.lang.reflect.Method.invoke (Method.java)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:524)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:987)
Caused by: java.lang.NullPointerException: 
  at androidx.core.os.UserManagerCompat.isUserUnlocked (UserManagerCompat.java:1)
  at com.google.firebase.FirebaseApp.initializeAllApis (FirebaseApp.java:1)
  at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:4)
  at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:1)
  at com.google.firebase.FirebaseApp.initializeApp (FirebaseApp.java:1)
任何解决方法？

有人知道运行Android 9的华为手机存在问题吗？尝试访问时，它始终返回null：context.getSystemService（UserManager.class）问题是大量的API ...

Answer 1

Answer 2