How to go from one fragment to another fragment in kotlin?

Question

I have a button in fragment A and when I click on fragment A, I want it to be redirected to fragment B. How to achieve this in kotlin? Right now I am using this code but app crash.

btntest.setOnClickListener {
            var intent = Intent(view.context, FragmentB::class.java)
            startActivity(intent)
        }

Answer 1

I'd suggest you take a look on the navigation component. First, you create a Navigation resource file (usually referred to as Nav Graph), where you add the fragments you wish to connect. Make sure to give an ID to each fragment (that's what you'll use to navigate between them later). Additionally, you can use app:startDestination in order to set the first fragment to be shown.

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    app:startDestination="@id/blankFragment">
    <fragment
        android:id="@+id/blankFragment"
        android:name="com.example.cashdog.cashdog.BlankFragment"
        android:label="@string/label_blank"
        tools:layout="@layout/fragment_blank" />
</navigation>

Then, in the activity/fragment that will be hosting the fragments, add a FragmentContainerView and set the graph to the one you created.

<?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">

    <androidx.fragment.app.FragmentContainerView
        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" />

</androidx.constraintlayout.widget.ConstraintLayout>

Finally, in order to navigate between fragments, use this in the Activity that is hosting the navigation (use getActivity() if a Fragment is hosting the navigation).

// as per defined in your FragmentContainerView
val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
val navController = navHostFragment.navController

// Navigate using the IDs you defined in your Nav Graph
navController.navigate(R.id.blankFragment)

Source: https://developer.android.com/guide/navigation/navigation-getting-started

Edit: if you want to access the controller within your Fragment, use activity?.supportFragmentManager to get the fragment manager.