I am trying to implement a simple swiping action between the three main screens of my app (feed, forum & profile). I've been looking for guides online but they all seem to take the same approach and show how to implement the adapter using fragments that are simple instances of a basic class that for example just inflates a title and a number on the screen.
In my case, the fragments are not all instances of the same class and are completely different.
M problem lays in the FragmentPagerAdapter. I am not sure how to return each fragment in the getItem method.
I have tried the following but it doesn't except it as a valid return statement and is still expecting one:
class PagesPagerAdapter(fragmentManager: FragmentManager) : FragmentPagerAdapter(fragmentManager) {
override fun getItem(p0: Int): Fragment? {
return when (p0){
0 -> FeedFragment.newInstance()
1 -> BoardFragment.newInstance()
2 -> ProfileFragment.newInstance()
else -> FeedFragment.newInstance()
}
}
override fun getCount(): Int {
return 3
}
}
This is an example of one of my fragments:
class FeedFragment : Fragment() {
val galleryAdapter = GroupAdapter<ViewHolder>()
private fun setUpGalleryAdapter() {
feed_gallary.adapter = galleryAdapter
val galleryLayoutManager = GridLayoutManager(this.context, 3)
feed_gallary.layoutManager = galleryLayoutManager
val dummyUri =
"https://firebasestorage.googleapis.com/v0/b/dere-3d530.appspot.com/o/20150923_100950.jpg?alt=media&token=97f4b02c-75d9-4d5d-bc86-a3ffaa3a0011"
val imageUri = Uri.parse(dummyUri)
if (imageUri != null) {
galleryAdapter.add(FeedImage(imageUri))
galleryAdapter.add(FeedImage(imageUri))
galleryAdapter.add(FeedImage(imageUri))
galleryAdapter.add(FeedImage(imageUri))
galleryAdapter.add(FeedImage(imageUri))
}
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
setUpGalleryAdapter()
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
inflater.inflate(R.layout.fragment_feed, container, false)
companion object {
fun newInstance(): FeedFragment = FeedFragment()
}
}
And this is my main activity:
class MainActivity : AppCompatActivity() {
private lateinit var viewPager: ViewPager
private lateinit var pagerAdapter: PagesPagerAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewPager = findViewById<ViewPager>(R.id.view_pager)
pagerAdapter = PagesPagerAdapter(supportFragmentManager)
viewPager.adapter = pagerAdapter
}
}
I have also tried to define a variable currentFragment, have it reassigned for each of the when statements and have it be the return value, but as all my fragments are unique I am getting a type mismatch when trying to assign them all to one variable.
Is there some Array I can store the fragments in and then return the array position?
I feel like there is probably a simple elegant and common solution here.
Without seeing all of your code I cannot be sure but one thing to note is you must return an instance of your fragment not a reference to the class. Ex: FeedFragment() instead of FeedFragment.
Also, your when statement does not have a default case resulting in a compile error for the getItem method as you have a code path that doesn't return anything. Try the following code for getItem
override fun getItem(p0: Int): Fragment {
when(p0){
0 -> return FeedFragment.newInstance()
1 -> return BoardFragment.newInstance()
else -> return ProfileFragment.newInstance()
}
}