why onClickListener does not work in my fragment activity? - kotlin

Question

Im new in programming, and i got stuck with adding onClickListener in my FragmentHome.kt
i added this code to my existing activity:
val exc = this.findViewById<Button>(R.id.execute)
exc.setOnClickListener {
Toast.makeText(this, "You clicked me.", Toast.LENGTH_SHORT).show()
}
I tried set onClicklistener on a blank activity and it worked, but when i added it to an existing
Fragment activity it does nothing (it should display a toast with some text)
I see no error messages so i don't know where the problem could be.
Thank you for your responses.
enter code here
public class FragmentHome : Fragment() {
public class HomeFragmentElements : AppCompatActivity() {
private lateinit var spinView: Spinner
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.fragment_home)
val exc = this.findViewById<Button>(R.id.execute)
exc.setOnClickListener {
Toast.makeText(this, "You clicked me.", Toast.LENGTH_SHORT).show()
}
spinView = findViewById(R.id.spinner)
spinView.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onItemSelected(
parent: AdapterView<*>?,
view: View?,
position: Int,
id: Long
) {
TODO("Not yet implemented")
}
override fun onNothingSelected(parent: AdapterView<*>?) {
TODO("Not yet implemented")
}
}
}
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home, container, false)
}
}
enter code here

Answer 1

Try to put your code into "onViewCreated":
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val exc = this.findViewById<Button>(R.id.execute)
exc.setOnClickListener {
Toast.makeText(this, "You clicked me.", Toast.LENGTH_SHORT).show()
}
}
onViewCreated is executed after "onCreateView". View bindings and initializations should be into onViewCreated

Answer 2

change the following in your onCreateView
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view: View = inflater.inflate(R.layout.fragment_home, container, false)
collectId(view)
return view
}
fun collectId(view: view){
val exc = view.findViewById<Button>(R.id.execute)
exc.setOnClickListener {
Toast.makeText(this, "You clicked me.", Toast.LENGTH_SHORT).show()
}
}
You can consider viewBinding instead of findViewById

Answer 3

It looks like you have defined an AppCompatActivity subclass inside your Fragment class's definition, kind of like this:
class MyFragment: Fragment {
class MyActivity: AppCompatActivity() {
//...
}
}
The ability to define a non-inner class in a nested way is purely a code organization tool. There is absolutely no connection between your Fragment and Activity classes here. The code above is no different than if you did this, with each class in a completely different file:
class MyFragment: Fragment {
}
class MyActivity: AppCompatActivity() {
}
It also doesn't make sense to think of an Activity as a child of a Fragment. A Fragment is a piece of an Activity, so it's the other way around.
All the code that you have in this Activity's onCreate should be put in the Fragment's onViewCreated() function, except for the call to setContentView(), because that's what your overriding of onCreateView() does. And remove the unused nested Activity class.
Also, you don't need to override onCreateView if you're simply inflating a layout and returning it. You can put the layout directly in the super-constructor call like this:
public class FragmentHome : Fragment(R.layout.fragment_home) {
private lateinit var spinView: Spinner
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
// your view setup code
}
}