Fragment

• A fragment represents a modular portion of the user interface within an activity. A fragment has its own lifecycle, receives its own input events, and you can add or remove fragments while the containing activity is running.

• Fragment are part of an activity.

• It is Similar to an activity but not an Activity .

• A Activity may contains multiple fragments .

• Fragment has its own lifecycle like activity

Fragment LifeCycle Compare to Activity LifeCycle

Create An Fragment

• Right click on layout folder or project named folder in android studio.

• select Fragment.

• Select Blank Fragment OR Fragment According to your need.

Use Fragment

• Fragment need to Instantiate OR Initialized Inside an Activity And Need to place in side some Container View Like ( FrameLayout , etc…)

Method To create/Invoke Fragment

1. Using Fragment Manager

• Old Style

val homeFragment = HomeFragment()

val ft : FragmentTransaction = supportFragmentManager.beginTransaction()

// add new fragment to layout container 
//  add to back Stack 
ft.add(R.id.framelayout , homeFragment)
//     OR 

// replace prev fragment with new fragment 
// does not add to back stack 
ft.replace(R.id.framelayout , homeFragment)

// commit the chnages 
ft.commit()

• We Need FragmentManager for Fragment it can be get by supportFragmentManager

• than we need FragmentTransaction object to perform transaction it can get by beginTransaction() method of supportFragmentManager

• FragmentTransaction object contains multiple methods to perform transactions of fragments and last we need to perform commit() method of it to complete the transaction .

2. Using Nav Controller And Navigation Graph

• New Approach

• Easy , Simple And Removes Boiler Code.

• Articles about it

Navigation Component- The Complete Guide

Android Jetpack is a set of components, tools, libraries and guidance to help developers to create a brilliant quality-oriented…

https://medium.com/@muhamed.riyas/navigation-component-the-complete-guide-c51c9911684

Android Navigation Component

The Compass To Your Navigation Needs

https://proandroiddev.com/android-navigation-component-fc783c03bb8d

Steps:

1. Add Dependencies in Gradle fire of Module and Sync Project

implementation "androidx.navigation:navigation-fragment-ktx:2.7.7"
implementation "androidx.navigation:navigation-ui-ktx:2.7.7"

2. right click on res folder that select new then Android resource directory
• select or create navigation directory
• right click on navigation folder and click on new
• then select Navigation Resource File and name it nav_graph.xml file.

3. Click on Add Fragment Button and add all Fragment in This nav_graph.xml file

2. Connect Fragments with each Other Like You Want Navigate and draw map of navigation.

5. Inside Activity from where you want to hold / create fragment it need some container to Host the fragments so Inside Layout file of activity add this
• acitivity_main.xml

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph" />

6. Inside Activity from where you want to change fragment Create NavController object
• The navigation controller is one of the key concepts in navigation. It holds the navigation graph and exposes methods that allow your app to move between the destinations in the graph.

private lateinit var navController: NavController


// To Initialize inside activity 
// ... Inside onCreate Method 
navController = Navigation.findNavController(this@MainActivity,R.id.nav_host_fragment)

// OR 

// To Initialize inside fragment 
 override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        navControtter = Navigation.findNavControtter(view)
    }

2. Now to We can Navigation between fragment for that perform this code on some button or condition

navController.navigate(R.id.action_blankFragment1_to_blankFragment2)