Android Studio Giraffe Essentials - Kotlin Edition by Neil Smyth

Author:Neil Smyth
Language: eng
Format: epub
Publisher: Payload Media, Inc.
Published: 2023-08-11T19:02:10+00:00

action.message = binding.userText.text.toString()

Navigation.findNavController(it).navigate(action)

}

The above code obtains a reference to the action object, sets the message argument string using the setMessage() method, and then calls the navigate() method of the navigation controller, passing through the action object. If Android Studio reports FirstFragmentDirections as undefined, rebuild the project using the Build -> Make Project menu option to generate the class.

All that remains is to modify the SecondFragment.kt class file to receive the argument after the navigation has been performed and display it on the TextView widget. For this example, the code to achieve these tasks will be added using an onStart() lifecycle method. Edit the SecondFragment.kt file and add this method so that it reads as follows:

override fun onStart() {

super.onStart()

arguments?.let {

val args = SecondFragmentArgs.fromBundle(it)

binding.argText.text = args.message

}

}

The code in the above method begins by obtaining a reference to the TextView widget. Next, the fromBundle() method of the SecondFragmentArgs class is called to extract the SecondFragmentArgs object received from the origin. Since the argument in this example was named message in the navigation_graph.xml file, the corresponding getMessage() method is called on the args object to obtain the string value. This string is then displayed on the TextView widget.

Compile and run the app and enter some text before clicking on the Button widget. When the second fragment destination appears, the TextView should display the text entered in the first fragment, indicating that the data was successfully passed between navigation destinations.

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