ViewPager 예제

ViewPager 

MainActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        initViewPager()
    }


    private fun initViewPager() {

        val adapter = MyPagerAdapter(supportFragmentManager)

        var firstFragmet: MyFragment = MyFragment.newInstance("찻번째 프레그먼트")
        var secondFragmet: MyFragment = MyFragment.newInstance("두번째 프레그먼트")
        var thirdFragmet: MyFragment = MyFragment.newInstance("두번째 프레그먼트")

        adapter.addFragment(firstFragmet, "첫번째")
        adapter.addFragment(secondFragmet, "두번째")
        adapter.addFragment(thirdFragmet, "세번째")

        viewpager!!.adapter = adapter
        tabs!!.setupWithViewPager(viewpager)
    }
}

MyPagerAdapter

class MyPagerAdapter(manager: FragmentManager) : FragmentPagerAdapter(manager) {

    private val mFragmentList: ArrayList<Fragment> = ArrayList() //프레그먼트
    private val mFragmentTitleList: ArrayList<String> = ArrayList() //프레그먼트의 이름

    override fun getItem(position: Int): Fragment {
        return mFragmentList.get(position)
    }

    override fun getCount(): Int {
        return mFragmentList.size
    }

    fun addFragment(fragment: Fragment, title: String) {
        mFragmentList.add(fragment)
        mFragmentTitleList.add(title)
    }

    override fun getPageTitle(position: Int): CharSequence? {
        return mFragmentTitleList.get(position)
    }
}

MyFragment

class MyFragment : Fragment() {

    companion object {
        fun newInstance(message: String): MyFragment {

            val f = MyFragment()
            val bdl = Bundle(1)
            bdl.putString(EXTRA_MESSAGE, message)
            f.arguments = bdl
            return f
        }
    }


    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {

        var view: View? = inflater.inflate(R.layout.fragment_home, container, false)
        val message = arguments!!.getString(EXTRA_MESSAGE)
        var textView: TextView = view!!.findViewById(R.id.text)
        textView!!.text = message

        return view
    }
}

- 스태틱매소드인 newInstance 을 이용해 MyFragment의 인스턴스를 찍어낸다.

- Myfragment의 argument에 Bundle을 넣어줘서 초기화 데이터를 전송할 수 있다.

- onCreateView 에서  arguments 로 받아서 사용. 

  argument는 Myfragment의 인자이다. 

  구글문서의 코드 참조: https://developer.android.com/guide/components/fragments?hl=ko

fragment_my.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".MyFragment">

    <TextView
            android:id="@+id/text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="test" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent" android:textSize="100dp"/>

</android.support.constraint.ConstraintLayout>

MyFragment2

class MyFragment2 : Fragment() {

    companion object {
        fun newInstance(): MyFragment2 {
            return MyFragment2()
        }
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        var view: View? = inflater.inflate(R.layout.fragment_other, container, false)
        return view
    }
}

최소부분만 구현.

XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
              android:orientation="vertical">

    <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:tabGravity="fill"
            app:tabMode="fixed" tools:layout_editor_absoluteY="188dp" tools:layout_editor_absoluteX="0dp"/>

    <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="match_parent" app:layout_constraintTop_toBottomOf="@+id/tabs"
            android:layout_marginTop="252dp" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
            app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
            android:layout_marginBottom="8dp" app:layout_constraintBottom_toBottomOf="parent"/>

</android.support.constraint.ConstraintLayout>

//Tablayout
implementation 'com.android.support:design:28.0.0'

Google Fragment 문서: https://developer.android.com/guide/components/fragments?hl=ko

아래 예제는 동일한 xml레이아웃에 내용만 바꿔넣는 형태.

참고: http://www.kotlincodes.com/kotlin/viewpager-in-kotlin-android/