（转）Activity中多fragment使用NavHostFragment导航用法

会自动添加fragment依赖

implementation 'androidx.navigation:navigation-fragment-ktx:2.3.0'
implementation 'androidx.navigation:navigation-ui-ktx:2.3.0'

容器nav_container，用来放fragment

<?xml version="1.0" encoding="utf-8"?>
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/nav_container"
app:startDestination="@id/nav1Fragment">

android:id="@+id/nav1Fragment"
android:name="com.bliss.myapp.Nav1Fragment"
android:label="fragment_nav1"
tools:layout="@layout/fragment_nav1" >
android:id="@+id/action_nav1Fragment_to_nav2Fragment2"
app:destination="@id/nav2Fragment"
app:popEnterAnim="@anim/slide_in_left"
app:popExitAnim="@anim/slide_out_right"
app:enterAnim="@anim/slide_in_right"
app:exitAnim="@anim/slide_out_left"/>

android:id="@+id/nav2Fragment"
android:name="com.bliss.myapp.Nav2Fragment"
android:label="fragment_nav2"
tools:layout="@layout/fragment_nav2" />


activity中引用fragment容器
引用容器nav_container

android:id="@+id/nav_host_fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_container"
android:name="androidx.navigation.fragment.NavHostFragment"/>

app:defaultNavHost=“true” 该Fragment会自动处理系统返回键，即，当用户按下手机的返回按钮时，系统能自动将当前的Fragment推出。
app:navGraph 设置该Fragment对应的导航图 。
容器中在design视图下创建fragment

fragment间跳转
view.findViewById(R.id.btnToSecondFragment).setOnClickListener(Navigation.createNavigateOnClickListener(R.id.action_nav1Fragment_to_nav2Fragment2))

fragment跳转动画
android:id="@+id/nav1Fragment"
android:name="com.bliss.myapp.Nav1Fragment"
android:label="fragment_nav1"
tools:layout="@layout/fragment_nav1" >
android:id="@+id/action_nav1Fragment_to_nav2Fragment2"
app:destination="@id/nav2Fragment"
app:popEnterAnim="@anim/slide_in_left"
app:popExitAnim="@anim/slide_out_right"
app:enterAnim="@anim/slide_in_right"
app:exitAnim="@anim/slide_out_left"/>


转场动画
app:popEnterAnim 点击返回键action所在元素入场的动画，是Fargment1入场的动画
app:popExitAnim 点击返回 ，Fragment2离场的动画
app:enterAnim action目的地进入的动画,是Fragment2入场的动画
app:exitAnim 这个action所在元素离开的动画，是Fargment1离场的动画
Bundle传参
class Nav1Fragment : Fragment(),View.OnClickListener {
var parms = Bundle()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
var view = inflater.inflate(R.layout.fragment_nav1, container, false)
parms.putString("name","秦时明月")
// view.findViewById

(R.id.btnToSecondFragment).setOnClickListener(Navigation.createNavigateOnClickListener(R.id.action_nav1Fragment_to_nav2Fragment2,parms))
view.findViewById(R.id.btnToSecondFragment).setOnClickListener(this)
return view
}

override fun onClick(view: View?) {
when(view?.id){
R.id.btnToSecondFragment -> Navigation.findNavController(view).navigate(R.id.action_nav1Fragment_to_nav2Fragment2,parms)
}
}
}

class Nav2Fragment : Fragment() {

override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
var param1 = arguments
var view = inflater.inflate(R.layout.fragment_nav2, container, false)
Log.e("TAG", "onCreateView: param == $param1" )
if (param1!=null){
var name = param1?.get("name")
Log.e("TAG", "onCreateView: name == $name" )
}
return view
}

}


safe args传参
APP根目录下的build.gradle添加依赖

def nav_version = "2.3.0-alpha01"
classpath "androidx.navigation:navigation-safe-args-gradle-plugin:$nav_version"

在app的build.gradle文件中添加

apply plugin: 'androidx.navigation.safeargs'

在导航图中添加标签。我们可以直接在Text中编写XML代码，也可以通过Design面板添加
android:id="@+id/nav1Fragment"
android:name="com.bliss.myapp.Nav1Fragment"
android:label="fragment_nav1"
tools:layout="@layout/fragment_nav1" >
android:id="@+id/action_nav1Fragment_to_nav2Fragment2"
app:destination="@id/nav2Fragment"
app:popEnterAnim="@anim/slide_in_left"
app:popExitAnim="@anim/slide_out_right"
app:enterAnim="@anim/slide_in_right"
app:exitAnim="@anim/slide_out_left"/>
android:name="age"
app:argType="integer"
android:defaultValue="0">

rebuild 项目，会生成对应的参数相关的代码

利用生成的代码传递参数
var safeArgs = Nav1FragmentArgs.Builder().setAge(100).build().toBundle() //safeargs传参
when(view?.id){
R.id.btnToSecondFragment -> Navigation.findNavController(view).navigate(R.id.action_nav1Fragment_to_nav2Fragment2,safeArgs)
// R.id.btnToSecondFragment -> Navigation.findNavController(view).navigate(R.id.action_nav1Fragment_to_nav2Fragment2,parms)
}

其他fragment接受参数
if (arguments != null){
var safeArgs = Nav1FragmentArgs.fromBundle(requireArguments()).age
Log.e("TAG", "onCreateView: safeArgs = =$safeArgs" )
}
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原文链接：https://blog.csdn.net/ytfunnysite/article/details/108667383