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Navigation - are you sure you want to take a look at such an easy-to-use navigation framework?
2022-07-07 14:26:00 【InfoQ】
Preface
What is? Navigation？ Official documents are a little difficult to understand . therefore , Here I would like to sum up with my own words , We're dealing with Fragment It is necessary to write Fragment To operate Fragment Of , and Navigation The emergence of is to solve some pain points we developed before .Navigation Mainly used to realize Fragment Instead of Activity Page navigation function , Give Way Fragment It can easily jump and pass parameters , We can do that by using Navigation, Give Way Fragment Instead of android Most of the projects Activity. But it should be noted that in use Navigation Switch the changes of page life cycle , Avoid stepping on pits in the development process .
Official documents ：
https://developer.android.google.cn/jetpack/androidx/releases/navigation
navigation Project address ：
https://github.com/googlecodelabs/android-navigation
this paper Demo Address ：
https://github.com/taxze6/Jetpack_learn/tree/main/Jetpack_basic_learn/navigation
Use Navigation What's the advantage ？
- Handle Fragment Business
- By default , Can correctly handle round-trip operations
- Provide standardized resources for animation and transformation
- Implement and handle deep links
- Including navigation interface mode , For example, drawer navigation bar and bottom navigation , We only need to complete a small amount of code
- Safe Args - Provides type safe navigation and data transfer between targets Gradle plug-in unit
- ViewModel Support - You can use ViewModel The scope of is limited to the navigation map , To share data related to the interface between the targets of the icon
How to use Navigation Well ？
Navigation At present, only AndroidStudio 3.2 Above version support , If your version is insufficient 3.2, please
Download this
The latest version AndroidStudio(2202 No one should still use it after years 3.2 The following version !)
Starting to learn
Navigation Before component , We need to be right first
Navigation Have a simple understanding of the main components ,Navigation It's made up of three parts ：
- Navigation graph： One that contains all navigation related information
XMLresources
- NavHostFragment： A special kind
Fragment, Container used to hold navigation content
- NavController： Manage application navigation objects , Realization
FragmentBetween the jump and other operations
Now let's start learning Navigation La
First step ： Add dependency
//project Of Navigation Dependency settings
dependencies {
// The latest stable version when the article is released ：
def nav_version = "2.4.2"
// Use java Add the following two lines as the development language ：
implementation "androidx.navigation:navigation-fragment:$nav_version"
implementation "androidx.navigation:navigation-ui:$nav_version"
// Kotlin：
implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
}
//Compose edition ：
implementation "androidx.navigation:navigation-compose:$nav_version"
The second step ： Create a navigation map
①
Right click on the
res Catalog , Then select
New→
Android Resource Directory. The system displays
New Resource Directory Dialog box .
Directory name Enter your folder name （ It's usually
navigation）,
Resource type choice
navigation②
Right click
navigation Folder , then
new →
Navigation Resource File stay
File name Enter a name in （ Commonly used
nav_graph_main or nav_graph
）
The third step ： establish Fragment
In order to enrich the jump , Here we create three
Fragment We can create it manually ：
FirstFragment:
<?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=".FirstFragment">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="hello world" />
</FrameLayout>
class FirstFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_first, container, false)
}
}
Create two more and
FirstFragement Same ：
SecondFragment,
ThirdFragment We can also pass
Navigation graph establish
We are building a new one
nav_graph_main.xml Next , Switch to... In the upper right corner
Design Pattern , And then in
Navigation Editor in , Click on
Create new destination, Choose what you need
Fragment after , Click on
Finish, You'll find out
Fragment It has appeared in the panel we can drag .
Step four ： take Fragment Drag into the panel and configure the jump
Only need
Navigation Editor Double click the desired
Fragment It will be added to the panel .
Click on one of
Fragment, You'll find that , There will be a dot on his right , Drag the dot to point to the one you want to jump
Fragment, We set up
FirstFragment →
SecondFragment →
ThirdFragment →
FirstFragment
We will
nav_graph_main.xml Switch to
Code Next , Let's interpret
xml<?xml version="1.0" encoding="utf-8"?>
<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_main"
app:startDestination="@id/firstFragment">
<fragment
android:id="@+id/firstFragment"
android:name="com.taxze.jetpack.navigation.FirstFragment"
android:label="fragment_first"
tools:layout="@layout/fragment_first" >
<action
android:id="@+id/action_firstFragment_to_secondFragment2"
app:destination="@id/secondFragment" />
</fragment>
<fragment
android:id="@+id/secondFragment"
android:name="com.taxze.jetpack.navigation.SecondFragment"
android:label="fragment_second"
tools:layout="@layout/fragment_second" >
<action
android:id="@+id/action_secondFragment_to_thirdFragment2"
app:destination="@id/thirdFragment" />
</fragment>
<fragment
android:id="@+id/thirdFragment"
android:name="com.taxze.jetpack.navigation.ThirdFragment"
android:label="fragment_third"
tools:layout="@layout/fragment_third" >
<action
android:id="@+id/action_thirdFragment_to_firstFragment"
app:destination="@id/firstFragment" />
</fragment>
</navigation>
navigationIt's a label , adoptstartDestinationConfigure the first page launched by default , The configuration here isfirstFragment, We can change it manually in the codemainFragment( The first one at startup Fragment), You can also clickFragment, Click againAssign Start Destination, You can also modifymainFragment
fragmentThe label means this is a Fragment
actionTags define the behavior of page jumps , Each line in the above figure ,destinationDefine the target page for jump , You can also add animation during jump
Be careful ： stay fragment Label under android:name attribute , Whether the package name is correctly declared
Step five ： Handle MainActivity
①
edit
MainActivity Layout file for , Add in the layout file
NavHostFragment. We need to tell
Navigation and
Activity, our
Fragment Where is the show , therefore
NavHostFragment In fact, it is the container of the navigation interface
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<fragment
android:id="@+id/nav_host_fragment"
android:layout_width="0dp"
android:layout_height="0dp"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph_main" />
</androidx.constraintlayout.widget.ConstraintLayout>
fragmentLabel underandroid:nameIs used to designateNavHostFragment
app:navGraphIs used to specify the Navigation view
app:defaultNavHost=trueEvery timeFragmentWhen switching , Save the click record in the stack , When you need to exit , After pressing the back key , You'll get it from the stack last timeFragmentDisplay . But in some cases , Such operation is not very friendly , But fortunately, we just need toapp:defaultNavHost=trueChange it toapp:defaultNavHost=falseOr delete this line . When it isfalseUnder the circumstances , No matter how you switchFragment, Click the back button again and exit directlyapp. Of course, we can also listen to its stack , So as to achieve , Click the back button once to return to the home page , Click the back button again to exitapp.
②
modify
MainActivity We rewrote
onSupportNavigateUp, That we will
Activity Of
back Click event delegation
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
override fun onSupportNavigateUp(): Boolean {
return findNavController(R.id.nav_host_fragment).navigateUp()
}
}
Step six ： Handle Fragment Corresponding jump event of
①
Fragment Layout ： Give a button to jump , One
TextView Used to identify , Three
Fragment The layout is the same
<?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=".FirstFragment">
<Button
android:id="@+id/firstButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text=" Click to jump to the second fragment" />
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="@string/hello_first_fragment" />
</FrameLayout>
//secondFragment Add :
<Button
android:id="@+id/firstButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text=" Click to jump to the third fragment" />
//thirdFragment Add ：
<Button
android:id="@+id/firstButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text=" Return to the first fragment" />
② To configure Fragment Corresponding jump event
class FirstFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_first, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
view.findViewById<Button>(R.id.firstButton).apply {
setOnClickListener {
it.findNavController().navigate(R.id.action_firstFragment_to_secondFragment2)
}
}
}
}
//secondFragment Add ：
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
view.findViewById<Button>(R.id.firstButton).apply {
setOnClickListener {
it.findNavController().navigate(R.id.action_secondFragment_to_thirdFragment2)
}
}
}
//thirdFragment Add ：
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
view.findViewById<Button>(R.id.firstButton).apply {
setOnClickListener {
it.findNavController().navigate(R.id.action_thirdFragment_to_firstFragment)
}
}
}
Among them
R.id.action_firstFragment_to_secondFragment2 Such a sign , Is in
nav_graph_main.xml Of
action Configured under the label .
<action
android:id="@+id/action_firstFragment_to_secondFragment2"
app:destination="@id/secondFragment" />
③ The final rendering ：
Jump animation & Custom animation
We will find that , In the example just now , When we jump to the interface , There is no animation of sliding left and right into the interface , Looks very stiff , So we need to add animation to the jump process .
①
Add default animation ：
stay
nav_graph_main.xml In the document
Design In mode , Click to connect two
Fragment Line . Then you will find a
Animations The panel , And then we click
enterAnim The rightmost ellipse of these options , Then it pops up
Pick a Resoure The panel , We can choose the animation we need here , Here we set
nav_default_enter_anim. Empathy
exitAnim We also set an animation ,
nav_default_exit_anim. Then run the code and you will find a gradual jump animation . Then after configuring the animation, you will find
action More animation related attributes
<fragment
android:id="@+id/firstFragment"
android:name="com.taxze.jetpack.navigation.FirstFragment"
android:label="fragment_first"
tools:layout="@layout/fragment_first" >
<action
android:id="@+id/action_firstFragment_to_secondFragment2"
app:destination="@id/secondFragment"
app:enterAnim="@anim/nav_default_enter_anim"
app:exitAnim="@anim/nav_default_exit_anim"
/>
</fragment>
enterAnim: Animation of the target page when jumping
exitAnim: The original page animation when jumping
popEnterAnim: Animation of the target page when backing back
popExitAnim: Back to the original page animation
②
Custom animation
There are many different jump animations in the real business requirements , The official default animation is not enough , So we should learn to customize animation .
⑴ establish Animation Resource file
Right click on the
res Catalog , Then select
New→
Android Resource File. The system displays
New Resource File Dialog box .
File name Enter your folder name （ I'm going to set it to
slide_from_left）,
Resource type choice
Animation, Then we can send it to
res There is one more... In the catalog
anim Catalog , There are our customized animations .
⑵ Write our animation code
Here are some common examples ：
// Left slide effect
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:duration="300"
android:fromXDelta="-100%"
android:toXDelta="0%">
</translate>
</set>
// Right slide effect
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:duration="300"
android:fromXDelta="0%"
android:toXDelta="100%">
</translate>
</set>
// Rotation effect
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<scale
android:duration="1000"
android:fromXScale="0.0"
android:fromYScale="0.0"
android:pivotX="50%"
android:pivotY="50%"
android:toXScale="1.0"
android:toYScale="1.0" />
<rotate
android:duration="1000"
android:fromDegrees="0"
android:pivotX="50%"
android:pivotY="50%"
android:toDegrees="360" />
</set>
Common properties ：
Common settings ：
⑶ Use custom animation files
Using custom animation is the same as using default animation .
Rotation effect ：
How to pass data ？
Navigation Enables you to attach data to navigation operations by defining destination parameters . In general , It is recommended to pass a small amount of data . For example, passing userId, Rather than specific user information . If you need to transfer a lot of data , Still recommended ViewModel.
stay
nav_graph_main.xml In the document
Design In mode . Click to select
Fragment. On the right side of the
Attributes The palette , Click on
Arguments The plus sign to the right of the option . Add the required parameters . After adding parameters , In the arrow
Action Click on , It will be on the right
Argument Default Values Show this in
userId Variable , stay xml You can also see that
// Pseudo code , Do not directly cv
<fragment
...
>
...
<argument
android:name="userId"
android:defaultValue="1"
app:argType="integer" />
</fragment>
Code processing ：
// By default arrow Action Pass the parameters set in
it.findNavController().navigate(R.id.action_firstFragment_to_secondFragment2)
Transfer data dynamically
① We can use Bundle Pass parameters between destinations
// Pseudo code , Do not directly cv
view.findViewById<Button>(R.id.firstButton).setOnClickListener {
val bundle = Bundle()
bundle.putString("userId", "1")
val navController = it.findNavController()
navController.navigate(R.id.action_firstFragment_to_secondFragment2, bundle)
}
② Then we can accept the parameters
In the corresponding Fragment:
val tv = view.findViewById<TextView>(R.id.textView)
tv.text = arguments?.getString("userId")
stay Activity Use setGraph Switch between different Navigation
Usually , We are more than one
navigation The file of , We need to decide which one to use according to the business situation , Here we can use our
setGraph To switch between different
Navigation 了 .
① hold
activity_main in
fragment Label under
app:navGraph This attribute is removed
<fragment
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:defaultNavHost="true"/>
② In the code through
setGraph Set up
app:navGraphclass MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initNav(1)
}
private fun initNav(id: Int) {
var controller = Navigation.findNavController([email protected], R.id.nav_host_fragment)
if (id == 1) {
// Set the corresponding app:navGraph
controller.setGraph(R.navigation.first)
}
if (id == 2) {
controller.setGraph(R.navigation.second)
}
[email protected]()
}
}
Here we are , We're done
Navigation Most usage , Here are some important points , And learn and summarize this article through a case .
NavController
We have already talked about
Navigation Use , Processing
Fragment When the corresponding jump event of , We used
findNavController This method , Actually , This is
Navigation Of the three parts of
NavController One of them
api. So what is
NavController Well ？ It is responsible for operation
Navigation Under the framework of
Fragment Jump and exit 、 Animation 、 Monitor the current
Fragment Information , Of course, these are basic operations . Because except in
Fragment Call in , In practice, it can also be used in Activity Call in . If you can use it flexibly , It can help you realize any form of page Jump , You can also use
TabLayout coordination
Navigation Page design on the homepage .
How to get
NavController
What's the example? ？
In the previous basic use, we also used .
// Pseudo code , Do not directly cv
//activity:
//Activity.findNavController(viewId: Int)
findNavController(R.id.nav_host_fragment).navigateUp()
//Fragment:
//Fragment.findNavController()
//View.findNavController()
findNavController().navigate(R.id.action_thirdFragment_to_firstFragment)
Navigation Common operations ：
①popBackStack eject Fragment
Now let's start with
oneFragment Jump to
secondFragment On the way to
thirdFragment, Then we want to start from
thirdFragment go back to
secondFragment You can use it there
popBackStackoverride fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
.....
btn.setOnClickListener{
// eject Fragment
controller.popBackStack()
}
}
② Pop up to the specified Fragment
Is also used
popBackStack, This method can
Realize the need to empty the intermediate navigation stack
.
//xxxFragment Pop up to the specified Fragment.
// If the Boolean value of the second parameter is true It means that our parameter one Fragment Pop up together , It means that if it is false Just popBackStack To
//xxxFragment, If it is true, It's just xxxFragment stay popBackStack() once
controller.popBackStack(xxxFragment,true)
③navigateUp() Up Navigation
findNavController(R.id.nav_host_fragment).navigateUp()
navigateUp It is also the execution return to the upper level
Fragment The function of . and
popBackStack Function as . Then since it exists, it must have its special place .
navigateUp The function of upward return is actually a call
popBackStack Of . however ,
navigateUp There is a layer of judgment in the source code of , Judge this
Navigation Is it the last
Fragment. Use
popBackStack() If the current return stack is empty, an error will be reported , Because the stack is empty ,
navigateUp() Will not be , Or stay in the current interface .
④ Add navigation monitoring
val listener: NavController.OnDestinationChangedListener =
object : OnDestinationChangedListener() {
fun onDestinationChanged(
controller: NavController,
destination: NavDestination,
@Nullable arguments: Bundle?
) {
Log.d(TAG, "onDestinationChanged: id = ${destination.getId()}")
}
}
// Add listening
controller.addOnDestinationChangedListener(listener)
// Remove monitor
controller.removeOnDestinationChangedListener(listener)
⑤ Get the current navigation destination
Use
getCurrentDestination You can get the current navigation destination
// obtain
val destination = controller.getCurrentDestination()
Log.d(TAG, "onCreate: NavigatorName = ${destination.getNavigatorName()}")
Log.d(TAG, "onCreate: id = ${destination.getId()}")
Log.d(TAG, "onCreate: Parent = ${destination.getParent()}")
⑥ Judge what is displayed on the current page Fragment Is it a goal Fragment
// Directly cv
fun <F : Fragment> isActiveFragment(fragmentClass: Class<F>): Boolean {
val navHostFragment = this.supportFragmentManager.fragments.first() as NavHostFragment
navHostFragment.childFragmentManager.fragments.forEach {
if (fragmentClass.isAssignableFrom(it.javaClass)) {
return true
}
}
return false
}
Use Safe Args Make sure the type is safe
Through the top NavController We can do it fragment Jump between , however Google It is recommended to use Safe Args Gradle Plug-in implementation . This plug-in can generate simple objects and builder classes , These classes can safely navigate and pass parameters between destinations .
that , How to use
Safe Args Well .
① In the outermost part of the project
build.gradle Add
// Put it on plugins{} Before
buildscript {
repositories {
google()
}
dependencies {
def nav_version = "2.4.2"
classpath "androidx.navigation:navigation-safe-args-gradle-plugin:$nav_version"
}
}
② stay
app、
module Under the
build.gradle Join in
If you need to generate a for
Java Module or
Java and
Kotlin Of hybrid modules
Java The language code
apply plugin: "androidx.navigation.safeargs"
If you need to generate a for
Kotlin Unique module
Kotlin Code , Please add the following line ：
apply plugin: "androidx.navigation.safeargs.kotlin"
To use Safe Args, Must be in gradle.properties Add to this file
android.useAndroidX=true
android.enableJetifier=true
In order to avoid the generated class name and method name being too complex , The navigation map needs to be adjusted , Revised action Of id, Because of the auto generated id Is too long. , The class name and method name generated by the plug-in are also very long .
// Pseudo code , Do not directly cv
<fragment
android:id="@+id/blankFragment"
android:name="com.taxze.jetpack.navigation.BlankFragment"
android:label="fragment_blank"
tools:layout="@layout/fragment_blank" >
<action
android:id="@+id/toSecond"
Modify here id
app:destination="@id/blankFragment2" />
</fragment>
Then it will generate
BlankFragment and
BlankFragment2 Class of , Then it can be used as above , Pass parameters .
var action = BlankFragment.actionJump("111")
You can also use
set Method
Assign values to the corresponding parameters
action.setParam("222")
adopt Navigation imitation WeChat Bottom jump
adopt Navigation Realize the super common bottom jump function in development
Don't talk much , First on the renderings ：
① Right click on the
res Catalog , Then select
New→
Android Resource File. The system displays
New Resource File Dialog box .
File name Enter your folder name （ I'm going to set it to
menu）,
Resource type choice
Menu, Then we can send it to
res There is one more... In the catalog
menu Catalog , Inside is our bottom jump
item.
② Get into
menu.xml Of
Design Next
Fill in four
Item, And set it separately
id,
title,
icon
③ Create four
Fragment, And in
Navigation Build links in
Fragment The layout of the is very simple , Here is a code .
<?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=".HomeFragment">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="Home" />
</FrameLayout>
class HomeFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_home, container, false)
}
}
stay
nav_graph_main.xml Establishing a connection , Pay attention to each of these
Fragment Of
id Want to be with
menu.xml Medium
id One-to-one correspondence
④ stay
activity_main Use in
BottomNavigationView Create a bottom jump
Here it is
drawable Next create a
selector_menu_text_color.xml Used to distinguish the current
Item<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:color="#818181" android:state_checked="false"/>
<item android:color="#45C01A" android:state_checked="true"/>
</selector>
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<fragment
android:id="@+id/nav_host_fragment"
android:layout_width="0dp"
android:layout_height="0dp"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph_main" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:itemIconTint="@drawable/selector_menu_text_color"
app:labelVisibilityMode="labeled"
app:itemTextColor="@drawable/selector_menu_text_color"
app:menu="@menu/menu" />
</androidx.constraintlayout.widget.ConstraintLayout>
⑤ stay MainActivty Set the switching logic
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// Remove the title bar
supportRequestWindowFeature(Window.FEATURE_NO_TITLE)
setContentView(R.layout.activity_main)
val navController: NavController = Navigation.findNavController(this, R.id.nav_host_fragment)
val navigationView = findViewById<BottomNavigationView>(R.id.nav_view)
NavigationUI.setupWithNavController(navigationView, navController)
}
}
In this way, we can achieve the effect in the rendering , Specific code can be viewed
Git Warehouse
Epilogue
This article has been described in great detail Jetpack Navigation Most uses of , But after reading the article , You still need to practice more , I believe you will soon master Navigation La Because my ability is limited , If there is something wrong with the article, you are welcome to point out , If you have any questions, please leave a message in the comment area to discuss ~
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Foundation Series ：
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — Lifecycle
Learn how to use LiveData and ViewModel, I believe it will make you relaxed when writing business
When you really learn DataBinding after , You'll find that “ This thing smells good ”!
Navigation — Are you sure you don't want to take a look at such a useful jump management framework ？( this paper )
The following parts are still codewords , Hurry to order a collection
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — Room
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — Paging3
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — WorkManager
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — ViewPager2
2022 · Let me show you Jetpack Architecture components go from beginner to proficient — Login to the registration page （MVVM）
Advanced Series :
coroutines + Retrofit Network request status encapsulation
Room Cache encapsulation
.....
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