build.grandle
dependencies { implementation 'androidx.viewpager2:viewpager2:1.0.0-alpha02'} 2. xml布局中引用viewPager <?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/pagers" android:layout_width="match_parent" android:layout_height="180dp" android:orientation="horizontal" app:layout_constraintTop_toTopOf="parent"/> <LinearLayout android:id="@+id/dots" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:gravity="center_horizontal" app:layout_constraintTop_toTopOf="parent" android:layout_marginTop="160dp"> <ImageView android:layout_width="10dp" android:layout_height="10dp" android:background="@drawable/dot_selected"/> <ImageView android:layout_width="10dp" android:layout_height="10dp" android:background="@drawable/dot_unselected"/> <ImageView android:layout_width="10dp" android:layout_height="10dp" android:background="@drawable/dot_unselected"/> <ImageView android:layout_width="10dp" android:layout_height="10dp" android:background="@drawable/dot_unselected"/> </LinearLayout></androidx.constraintlayout.widget.ConstraintLayout> class MainActivity : AppCompatActivity() { var pics: MutableList<Int> = ArrayList() var dots: LinearLayout? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main)//3. 声明数组，将图片存入 pics.add(R.mipmap.bg1) pics.add(R.mipmap.bg2) pics.add(R.mipmap.bg3) pics.add(R.mipmap.bg4)//4. 创建适配器，完成资源配置 //实例化适配器(RecyclerView.Adapter) val adapter: RecyclerView.Adapter<*> = object : RecyclerView.Adapter<RecyclerView.ViewHolder>() { //创建 override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder { //此时用的布局是ViewPager每一页中用来乘放图片的布局 //该布局不设置任何控件，因为会直接将图片作为根布局的背景 val v = LayoutInflater.from(this@MainActivity).inflate(R.layout.item, parent, false) return ViewHolder(v) } //绑定(为ViewHolder里面的控件设置显示内容) override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) { val h = holder as MainActivity.ViewHolder h.container.setBackgroundResource(pics[position]) } //数量 override fun getItemCount(): Int { return pics.size } }//5. 为viewpager设置适配器 val pagers = findViewById<ViewPager2>(R.id.pagers) pagers.adapter = adapter var myDots = dots myDots = findViewById(R.id.dots) pagers.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() { override fun onPageSelected(position: Int) { super.onPageSelected(position) for (i in 0 until myDots.childCount) { (myDots.getChildAt(i) as ImageView).setBackgroundResource(R.drawable.dot_unselected) } (myDots.getChildAt(position) as ImageView).setBackgroundResource(R.drawable.dot_selected) } }) } inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { var container: LinearLayout = itemView.findViewById(R.id.container) }}