Android JetPack导航:如何从与其不相关的活动中打开片段? [英] Android JetPack Navigation : How to open a fragment from an activity not associated with it?

问题描述

场景:

MainActivity.kt :activity_main.xml包含my_nav_host_fragment

first_frag_dest 是startDestination，并且还有 second_frag_dest ，分别具有类FirstFragment.kt和SecondFragment.kt.

in mobile_navigation.xml first_frag_dest is the startDestination and there is second_frag_dest also, with respective classes FirstFragment.kt and SecondFragment.kt.

我已经设置了底部导航，可以使用Android Jetpack导航组件在两个片段之间进行切换.

I have setup bottom navigation for switch between two fragments using the Android Jetpack Navigation components.

如果FirbaseUser为null，则第一次打开第二个片段时，将启动一个为GoogleSignInusing Firebase配置的欢迎活动".

When the Second Fragment is opened for the first time if FirbaseUser is null, A Welcome Activity is launched which is configured for GoogleSignInusing Firebase.

在WelcomeActivity.java中，我有一个函数updateUI(user: FirebaseUser)来更新UI.

In WelcomeActivity.java I have a function updateUI(user: FirebaseUser) to update the UI.

现在，我应该在updateUI函数中编写什么代码，以便将我重定向回第二个片段.

Now, what code should I write in updateUI function such that I am redirected back to the Second Fragment.

请说明如何使用JetPack导航组件进行操作.

Please tell how to do it using JetPack Navigation components.

注意:导航原理说只有一个活动必须存在，但是由于Firebase的限制，在这里我不得不将一个活动用于GoogleSignIn.

推荐答案

如果要关闭WelcomeActivity并返回到其下方的活动，请使用updateUI方法调用

If you want to close your WelcomeActivity and return to the activity below it, have your updateUI method call finish():

活动结束后应调用此按钮

Call this when your activity is done and should be closed

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