Tuesday, February 27, 2018

android kotlin - ViewPager example

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.viewpager.widget.ViewPager


class MainActivity : AppCompatActivity() {

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

        // Get the widgets reference from XML layout
        val viewPager = findViewById<ViewPager>(R.id.viewPager)


        // Initialize a list of string values
        val alphabets = listOf("a","b","c","d","e","f")

        // Initialize a new pager adapter instance with list
        val adapter = AlphabetPagerAdapter(alphabets)

        // Finally, data bind the view pager widget with pager adapter
        viewPager.adapter = adapter
    }
}
activity_main.xml

<?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"
    android:id="@+id/rootLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCDCDC"
    android:padding="24dp">

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
page_layout.xml

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/tvColor"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:fontFamily="sans-serif"
        android:gravity="center"
        android:textSize="250sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/tvFooter"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tvFooter"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="end|bottom"
        android:textSize="20sp"
        android:textStyle="italic"
        app:layout_constraintBottom_toBottomOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
AlphabetPagerAdapter.kt

package com.cfsuman.kotlintutorials

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.viewpager.widget.PagerAdapter


class AlphabetPagerAdapter(private val list: List<String>)
    : PagerAdapter() {

    override fun isViewFromObject(v: View, `object`: Any): Boolean {
        // Return the current view
        return v === `object` as View
    }


    override fun getCount(): Int {
        // Count the items and return it
        return list.size
    }


    override fun instantiateItem(
        parent: ViewGroup, position: Int): Any {
        // Get the view from pager page layout
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.page_layout,parent,false)

        // Get the widgets reference from layout
        val tvColor: TextView = view.findViewById(R.id.tvColor)
        val tvFooter: TextView = view.findViewById(R.id.tvFooter)

        // Set the text views text
        tvColor.text = list[position]
        tvFooter.text = "Page ${position+1} of ${list.size}"

        // Add the view to the parent
        parent.addView(view)

        // Return the view
        return view
    }


    override fun destroyItem(
        parent: ViewGroup, position: Int, `object`: Any) {
        // Remove the view from view group specified position
        parent.removeView(`object` as View)
    }
}
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