导航组件操作不会在显示目标片段之前隐藏原始片段

时间：2019-02-06 16:52:29

标签： android kotlin android-jetpack android-architecture-navigation

我有一个使用新的Android Jetpack导航组件的新android应用程序。这是一个单独的活动MainActivity.kt，其中包含导航主机片段。图表的起点是loginFragment，并有一个动作action_log_in导航到homeFragment。基本结构如下：

Navigation Graph Example

由以下xml支持： 

<navigation 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:id="@+id/nav_graph"
app:startDestination="@id/loginFragment">
<fragment
    android:id="@+id/loginFragment"
    android:name="io.foobar.backtobasics.ui.pages.login.LoginFragment"
    android:label="LoginFragment" >
    <action
        android:id="@+id/action_log_in"
        app:destination="@id/homeFragment"
        app:enterAnim="@anim/nav_default_enter_anim"
        app:exitAnim="@anim/nav_default_exit_anim"
        app:launchSingleTop="false"
        app:popEnterAnim="@anim/nav_default_pop_enter_anim"
        app:popExitAnim="@anim/nav_default_pop_exit_anim"
        app:popUpTo="@+id/homeFragment"
        app:popUpToInclusive="true" />
</fragment>
<fragment
    android:id="@+id/homeFragment"
    android:name="io.foobar.backtobasics.ui.pages.home.HomeFragment"
    android:label="fragment_home"
    tools:layout="@layout/fragment_home" />
</navigation>

在使用“有效”凭据单击登录按钮后，应将用户导航到主屏幕。调用findNavController().navigate(R.id.action_log_in)时，没有任何反应。登录屏幕仍然可见。我删除了一些断点，发现HomeFragment已创建，但没有显示。登录片段仍然可见。当我尝试对Navigation调用进行变体时，但似乎没有任何效果。有人以前见过这样的行为吗？

以下是主要活动的Kotlin / Layout和两个片段。

MainActivity.kt 

class MainActivity : BaseActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val navController = findNavController(R.id.nav_host_fragment)
        findViewById<BottomNavigationView>(R.id.navigation).setupWithNavController(navController)
    }
}

activity_main.xml 

<layout>
<androidx.constraintlayout.widget.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:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.pages.home.MainActivity">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="0dp"
        android:layout_marginStart="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/navigation" />

</androidx.constraintlayout.widget.ConstraintLayout>

LoginFragment.kt 

class LoginFragment: Fragment() {

    private lateinit var vm: LoginViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setupBindings(savedInstanceState)
    }

    private fun setupBindings(savedInstanceState: Bundle?) {
        val binding: ActivityLoginBinding = DataBindingUtil.setContentView(requireActivity(), R.layout.activity_login)
        vm = ViewModelProviders.of(this@LoginFragment).get(LoginViewModel::class.java)
        if (savedInstanceState == null) vm = LoginViewModel(requireActivity().application)
        binding.vm = vm
        binding.executePendingBindings()
        setUpLoginButton()
    }


    private fun setUpLoginButton() {
        vm.getLoginClick().observe(this, Observer<LoginFields>{
            fields: LoginFields ->
            this.findNavController().navigate(R.id.homeFragment)
        })
    }
}

fragment_login.xml 

<?xml version="1.0" encoding="utf-8"?>

<layout>
    <data>
        <variable
            name="vm"
            type="io.foobar.backtobasics.ui.pages.login.LoginViewModel"/>
    </data>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_horizontal"
        android:orientation="vertical">
        <TextView
            android:id="@+id/title_label"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="20dp"
            android:gravity="top|center_horizontal"
            android:text="@string/label_title"
            android:textColor="@color/colorPrimary"
            android:textSize="60sp" />
        <com.google.android.material.textfield.TextInputLayout
            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="20dp"
            android:layout_marginTop="10dp"
            android:layout_marginEnd="20dp"
            android:layout_marginBottom="5dp"
            android:hint="@string/hint_username">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/username"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="textEmailAddress"
                android:text="@={vm.login.email}"
                app:error="@{vm.login.emailError}"
                app:onfocus="@{vm.getEmailOnFocusChangeListener()}" />
        </com.google.android.material.textfield.TextInputLayout>
        <com.google.android.material.textfield.TextInputLayout
            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="20dp"
            android:layout_marginTop="5dp"
            android:layout_marginEnd="20dp"
            android:layout_marginBottom="10dp"
            android:hint="@string/hint_password">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/password"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="textPassword"
                android:text="@={vm.login.password}"
                app:error="@{vm.login.passwordError}"
                app:onfocus="@{vm.getPasswordOnFocusChangeListener()}" />
        </com.google.android.material.textfield.TextInputLayout>
        <com.google.android.material.button.MaterialButton
            android:id="@+id/button"
            style="@style/Widget.MaterialComponents.Button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:enabled="@{vm.login.valid}"
            android:onClick="@{() -> vm.onLoginClicked()}"
            android:text="@string/button_login" />
    </LinearLayout>
</layout>

HomeFragment.kt 

class HomeFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        return inflater.inflate(R.layout.fragment_home, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
    }
}

fragment_home.xml 

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.pages.home.HomeFragment">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/title_home" />
</FrameLayout>

0 个答案:

没有答案
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