小编Ham*_*r83的帖子

我正在测试这个新库,并且如果用户没有登录则想要导航到登录片段.这个检查是在一个基本片段中完成的,例如:

abstract class SignedInFragment : Fragment() {

override fun onResume() {
    super.onResume()
    if (FirebaseAuth.getInstance().currentUser == null) {
        NavHostFragment.findNavController(this /* Fragment */)
                .navigate(R.id.action_login)
    }
}

}

但这只是在RuntimeException中结束,说FragmentManager已经在执行事务:

    java.lang.RuntimeException: Unable to resume activity {me.hammarstrom.loco/me.hammarstrom.loco.MainActivity}: java.lang.IllegalStateException: FragmentManager is already executing transactions
    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3645)
    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3685)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2898)
    at android.app.ActivityThread.-wrap11(Unknown Source:0)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

导航图如下所示:

<?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/mainFragment">

<fragment
    android:id="@+id/loginFragment"
    android:name="me.hammarstrom.loco.ui.login.LoginFragment"
    android:label="LoginFragment" >
    <action
        android:id="@+id/action_loginFragment_to_signedInFragment"
        app:destination="@id/signedInFragment"  /> …