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How to create a custom fragment animation in Kotlin Android

How to create a custom fragment animation in Kotlin Android.

Here is a detailed step-by-step tutorial on how to create a custom fragment animation in Kotlin for Android:

Step 1: Create a new Android project​

To begin, open Android Studio and create a new Android project. Choose an appropriate project name, package name, and other project settings.

Step 2: Define the animation XML files​

In this step, we will define the animation XML files that will be used for the fragment transitions. Create a new directory called "res" in the project's "app/src/main" directory if it doesn't already exist. Then, create a new directory called "anim" inside the "res" directory.

Inside the "anim" directory, create the following XML files:

  • slide_in_left.xml: This file defines the animation for sliding in a fragment from the left side of the screen.
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate
        android:fromXDelta="-100%"
        android:toXDelta="0%"
        android:duration="300"/>
</set>
  • slide_out_right.xml: This file defines the animation for sliding out a fragment to the right side of the screen.
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate
        android:fromXDelta="0%"
        android:toXDelta="100%"
        android:duration="300"/>
</set>

Step 3: Create the fragment classes​

In this step, we will create the fragment classes that will be used in the animation. Create a new Kotlin class called "FirstFragment" and another Kotlin class called "SecondFragment". These classes should extend the Fragment class.

Step 4: Implement the fragment transaction​

In this step, we will implement the fragment transaction with custom animations. Open the activity layout XML file (e.g., "activity_main.xml") and add a FrameLayout or any other container view to hold the fragments. Give it an appropriate ID (e.g., "@+id/fragment_container").

Next, open the MainActivity class and inside the onCreate() method, add the following code to perform the fragment transaction:

val fragmentManager = supportFragmentManager
val fragmentTransaction = fragmentManager.beginTransaction()

val firstFragment = FirstFragment()
val secondFragment = SecondFragment()

fragmentTransaction.add(R.id.fragment_container, firstFragment)
fragmentTransaction.commit()

Step 5: Define the custom fragment animations​

In this step, we will define the custom fragment animations for the fragment transaction. Modify the fragment transaction code as follows:

val fragmentManager = supportFragmentManager
val fragmentTransaction = fragmentManager.beginTransaction()

val firstFragment = FirstFragment()
val secondFragment = SecondFragment()

fragmentTransaction.setCustomAnimations(
    R.anim.slide_in_left,
    R.anim.slide_out_right,
    R.anim.slide_in_left,
    R.anim.slide_out_right
)

fragmentTransaction.add(R.id.fragment_container, firstFragment)
fragmentTransaction.commit()

Step 6: Test the custom fragment animation​

In this final step, run the application on an Android device or emulator to test the custom fragment animation. You should see the fragments sliding in and out with the defined custom animations.

That's it! You have successfully created a custom fragment animation in Kotlin for Android. You can further customize the animation XML files or implement different types of animations based on your requirements.