Passing Value from Activity to Fragment (PVAF)

I created a bottom navigation activity in my project, which contains one activity and two fragments. In Main Activity I have values ​​stored in variables but if I pass the values ​​to fragments then I get NullPointer Exception error. I am using kotlin in my project and any help is appreciated. Expectation:

Get Value into Fragment from MainActivity. MainActivity--->TestOneFragment

Error:

kotlin.KotlinNullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)

Solutip

Here is an example of the newInstancepola creating Fragments.

It's inside a companion object, which is a way of saying "this stuff is Static."

First, you need to define a constant for your Bundlename, this will help keep everything aligned. Next, define a newInstancemethod that takes your parameters, such as name.

And inside there, you will create a Fragment and return it. This way, your Activity doesn’t have to worry about Bundles or anything. All your logic is in one place, for storing/retrieving, all in the Fragment file.

class TestOneFragment {

    companion object {
        const val ARG_NAME = "name"


        fun newInstance(name: String): TestOneFragment {
            val fragment = TestOneFragment()

            val bundle = Bundle().apply {
                putString(ARG_NAME, name)
            }

            fragment.arguments = bundle

            return fragment
        }
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        val name = arguments?.getString(ARG_NAME)
        // ...
    }
}

And now, you can easily get Fragments by doing the following.

class Test : AppCompatActivity(), BottomNavigationView.OnNavigationItemSelectedListener {

    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        // ...

        val name = intent.getStringExtra("name")

        // Creating the new Fragment with the name passed in.
        val fragment = TestFragment.newInstance(name)
    }

}