ViewPager in Android

Overview

Viewpager is a layout manager which allows a user to flip left or right throughout the pages of our application with data.

Steps to create a static ViewPager

• Create an Enum for all the layouts

 enum class ModelObject(val titleId : Int , val layoutId : Int)
 {
    RED(R.string.red , R.layout.red_view) ,
    BLUE(R.string.blue , R.layout.blue_view) ,
    GREEN(R.string.green , R.layout.green_view);
 }

• Create a class and extend it with PagerAdapter. Apart from implementing the abstract methods isViewFromObject and getCount, you also have to override instantiateItem and destroyItem

 class CustomPagerAdapter(private val context : Context) : PagerAdapter()
 {
    override fun getCount() : Int
    {
        return ModelObject.values().size
    }

    override fun isViewFromObject(view : View , `object` : Any) : Boolean
    {
        return view == `object`
    }

    override fun instantiateItem(container : ViewGroup , position : Int) : Any
    {
        val modelObject : ModelObject = ModelObject.values()[position]
        val layoutInflater : LayoutInflater = LayoutInflater.from(context)
        val layout = layoutInflater.inflate(modelObject.layoutId , container , false)
        container.addView(layout)
        return layout
    }

    override fun destroyItem(container : ViewGroup , position : Int , `object` : Any)
    {
        container.removeView(`object` as View)
    }

 }

• Use the reference of ViewPager in MainActivity

 class MainActivity : AppCompatActivity()
 {
    override fun onCreate(savedInstanceState : Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        viewpager.adapter = CustomPagerAdapter(this)
    }
 }

Steps to create a static ViewPager2

• Add the required dependency in build.gradle (Module) file.

 implementation "com.google.android.material:material:1.6.0-alpha01"

• Add few images in drawable.
• Create a class for the adapter. Create an inner class and extend it with RecyclerView.ViewHolder. Then implement RecyclerView.Adapter in the class and override all the implementing methods.

 class ViewPagerAdapter(private val images : List<Int>) :
    RecyclerView.Adapter<ViewPagerAdapter.ViewPagerHolder>()
 {
    inner class ViewPagerHolder(itemView : View) : RecyclerView.ViewHolder(itemView)

    override fun onCreateViewHolder(parent : ViewGroup , viewType : Int) : ViewPagerHolder
    {
        val view =
            LayoutInflater.from(parent.context).inflate(R.layout.item_view_layout , parent , false)
        return ViewPagerHolder(view)
    }

    override fun onBindViewHolder(holder : ViewPagerHolder , position : Int)
    {
        val currentImage = images[position]
        holder.itemView.imgImageContainer.setImageResource(currentImage)
    }

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

• Set the adapter of ViewPager2 in MainActivity.

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

        val images = listOf(
            R.drawable.ic_4g ,
            R.drawable.ic_airport_shuttle ,
            R.drawable.ic_launcher_background ,
            R.drawable.ic_launcher_foreground
        )
        val adapter = ViewPagerAdapter(images)
        viewpager2.apply {
            this.adapter = adapter
            this.orientation = ViewPager2.ORIENTATION_VERTICAL
            this.beginFakeDrag()
            this.fakeDragBy(-10f)
            this.endFakeDrag()
        }
    }
 }

• Hello World

Reference

1. https://www.geeksforgeeks.org/viewpager-using-fragments-in-android-with-example/