20230915 ViewPager

ViewPager2

ViewPager2

화면 슬라이드 기능을 구현하는 데 사용되는 위젯 중 하나로 ViewPager와 비교해서 개선된 버전이다.

1. ViewPager2는 아이템 어탭터를 사용하여 각 화면의 콘텐츠를 관리. RecyclerView.Adapter와 유사하며 ViewPager2에 표시할 데이터와 뷰를 관리한다.(DiffUtil를 통한 뷰 재활용 가능)

2. 수평 및 수직 슬라이드를 모두 지원.

3. notifyDataSetChanged 문제 해결.

ViewPager2 만들기

1. 종속성 추가

    implementation 'androidx.viewpager2:viewpager2:1.0.0'

2. XML 파일에 viewpager2 추가

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/tapLayout"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tapLayout"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />


</androidx.constraintlayout.widget.ConstraintLayout>

3. 프래그먼트 추가
   @SearchFragment

class SearchFragment : Fragment() {

    private lateinit var binding: FragmentSearchBinding


    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentSearchBinding.inflate(inflater, container, false)

        return binding.root
    }
}

@LikeFragment

class LikeFragment : Fragment() {

    private lateinit var binding: FragmentLikeBinding

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentLikeBinding.inflate(inflater, container, false)

        return binding.root
    }
}

4.ViewPager2 어댑터 설정

class ViewPagerAdapter (fragmentActivity: FragmentActivity) : FragmentStateAdapter(fragmentActivity){

    private var fragments: ArrayList<Fragment> = arrayListOf(SearchFragment(), LikeFragment())

    override fun getItemCount(): Int {
        return fragments.size
    }

    override fun createFragment(position: Int): Fragment {
        return fragments[position]
    }
}

5. MainActivity

class MainActivity : AppCompatActivity() {

    private val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    private val tabTextList = listOf("검색결과", "내 보관함")

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.viewPager2.adapter = ViewPagerAdapter(this)

        TabLayoutMediator(binding.tapLayout, binding.viewPager2) { tab, pos ->
            tab.text = tabTextList[pos]
        }.attach()

    }
}