Navigation component of jetpack compose uses

Import dependence

    implementation 'androidx.appcompat:appcompat:1.4.2'
    implementation 'androidx.navigation:navigation-runtime-ktx:2.5.0'
    implementation 'androidx.navigation:navigation-fragment-ktx:2.5.0'
    implementation 'androidx.navigation:navigation-ui-ktx:2.5.0'

Create several as needed Fragment And Fragment The corresponding layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:text="register" />
</LinearLayout>

package com.example.wanandroid.ui.fragment

import android.content.Context
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.fragment.app.Fragment
import com.example.wanandroid.R

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

Create a navigation diagram

1. establish Navigation Catalog

res Right click the resource directory to create a new directory

2. establish xml file , For storage fragment Routing relationship between

3. To write nav_login.xml Code for ：

<?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"
    android:id="@+id/nav_login"
    app:startDestination="@id/loginFragment">
    <fragment
        android:id="@+id/loginFragment"
        android:name="com.example.wanandroid.ui.fragment.LoginFragment"
        android:label="LoginFragment">
        <action
            android:id="@+id/action_loginFragment_to_registerFragment"
            app:destination="@id/registerFragment" />
    </fragment>
    <fragment
        android:id="@+id/registerFragment"
        android:name="com.example.wanandroid.ui.fragment.RegisterFragment"
        android:label="RegisterFragment" />
</navigation>

4. The final structure is as follows ：

Label attribute description

establish activity Containers

Method 1 xml Use the default know to load the page without transferring parameters

Layout file ：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <fragment
        android:id="@+id/nav_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true" 
        app:navGraph="@navigation/nav_login"/>
</LinearLayout>

activity in ：

package com.example.wanandroid.ui

import android.os.Bundle
import androidx.navigation.NavController
import androidx.navigation.Navigation
import com.example.wanandroid.R

class LoginActivity: BaseCompatActivity() {
    
    lateinit var navController: NavController

    override fun getLayoutId(): Int {
    
        return R.layout.activity_login
    }

    override fun initView(savedInstanceState: Bundle?) {
    
        navController=Navigation.findNavController(this, R.id.nav_fragment)
    }

    override fun onSupportNavigateUp(): Boolean {
    
        return navController.navigateUp()
    }

}

Method 2: dynamically modify the default start page

Layout file （ Not set up navGraph attribute ）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <fragment
        android:id="@+id/nav_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"/>
</LinearLayout>

activity Dynamic settings in setGraph and setStartDestination：

package com.example.wanandroid.ui

import android.os.Bundle
import androidx.navigation.NavController
import androidx.navigation.Navigation
import com.example.wanandroid.R

class LoginActivity: BaseCompatActivity() {
    
    lateinit var navController: NavController

    override fun getLayoutId(): Int {
    
        return R.layout.activity_login
    }

    override fun initView(savedInstanceState: Bundle?) {
    
        navController=Navigation.findNavController(this, R.id.nav_fragment)

        navController.apply {
    
            var mNavGraph=navInflater.inflate(R.navigation.nav_login)
            mNavGraph.setStartDestination(when (1) {
    
                1 -> R.id.loginFragment
                else -> R.id.registerFragment
            })
            setGraph(mNavGraph,null)
        }

    }

    override fun onSupportNavigateUp(): Boolean {
    
        return navController.navigateUp()
    }

}

The start page fragment Click to jump to another fragment Key code

Attribute specification

attribute	explain
app:defaultNavHost=“true”	Indicates the return button event of the interception system
app:navGraph=“@navigation/nav_login”	NavHostFragment The associated navigation map is nav_login.xml

effect ：

Pass value

activity,fragment Indirect transmission value - receive

activity In the transfer ：

fragment In the receiving ：

Be careful ：Activity The ginseng , Every Fragment All available

fragment Indirect transmission value - receive

Pass on ：

receive ：