Data communication in Activity to Activity

 Extension function for data communication in activity to activity 

 inline fun <reified T : Activity> Context.openActivity(vararg params: Pair<String, Any>) {  
   val intent = Intent(this, T::class.java)  
   intent.putExtras(*params)  
   this.startActivity(intent)  
 }  
 fun Intent.putExtras(vararg params: Pair<String, Any>): Intent {  
   if (params.isEmpty()) return this  
   params.forEach { (key, value) ->  
     when (value) {  
       is Int -> putExtra(key, value)  
       is Byte -> putExtra(key, value)  
       is Char -> putExtra(key, value)  
       is Long -> putExtra(key, value)  
       is Float -> putExtra(key, value)  
       is Short -> putExtra(key, value)  
       is Double -> putExtra(key, value)  
       is Boolean -> putExtra(key, value)  
       is Bundle -> putExtra(key, value)  
       is String -> putExtra(key, value)  
       is IntArray -> putExtra(key, value)  
       is ByteArray -> putExtra(key, value)  
       is CharArray -> putExtra(key, value)  
       is LongArray -> putExtra(key, value)  
       is FloatArray -> putExtra(key, value)  
       is Parcelable -> putExtra(key, value)  
       is ShortArray -> putExtra(key, value)  
       is DoubleArray -> putExtra(key, value)  
       is BooleanArray -> putExtra(key, value)  
       is CharSequence -> putExtra(key, value)  
       is Array<*> -> {  
         when {  
           value.isArrayOf<String>() ->  
             putExtra(key, value as Array<String?>)  
           value.isArrayOf<Parcelable>() ->  
             putExtra(key, value as Array<Parcelable?>)  
           value.isArrayOf<CharSequence>() ->  
             putExtra(key, value as Array<CharSequence?>)  
           else -> putExtra(key, value)  
         }  
       }  
       is java.io.Serializable -> putExtra(key, value)  
     }  
   }  
   return this  
 }  

Simple using:

 startActivity<MainActivity>()  

With extra:

 startActivity<MainActivity>{  
   putExtra("param 1", "Simple")  
 }  

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ViewPager2 with recyclerView adapter

It was a nightmare working with viewPager when had to handle fragmentPagerAdapter. But in terms of viewPager2 its just fun. Cause we can easily use recyclerview adapter in ViewPager2. I have just done a demo project with custom indicator for viewPager2 with recyclerView Adapter. Let’s start coding step by step.

1. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <androidx.viewpager2.widget.ViewPager2
            android:id="@+id/view_Pager"
            android:layout_width="match_parent"
            android:layout_height="250dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/into_tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="200dp"
            app:layout_constraintTop_toTopOf="@+id/view_Pager"
            app:tabBackground="@drawable/pager_indicator"
            android:background="@android:color/transparent"
            app:tabGravity="center"
            app:tabIndicatorHeight="0dp"
            app:tabPaddingEnd="6dp"
            app:tabPaddingStart="6dp" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

2. MainActivity.kt

package com.piashcse.experiment.viewpager2withrvadapter

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.google.android.material.tabs.TabLayoutMediator
import com.piashcse.experiment.viewpager2withrvadapter.adapter.ImageSliderAdapter
import com.piashcse.experiment.viewpager2withrvadapter.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    private lateinit var bind: ActivityMainBinding
    private lateinit var imageSliderAdapter: ImageSliderAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        bind = DataBindingUtil.setContentView(this, R.layout.activity_main)
        viewPager2()
    }

    private fun viewPager2() {
        imageSliderAdapter = ImageSliderAdapter()
        bind.viewPager.adapter = imageSliderAdapter
        TabLayoutMediator(bind.intoTabLayout, bind.viewPager)
        { tab, position ->
        }.attach()
        imageSliderAdapter.addItem(
            listOf(
                "https://cdn.pixabay.com/photo/2021/01/09/02/13/manhattan-5901178_960_720.jpg",
                "https://cdn.pixabay.com/photo/2020/11/22/20/45/venice-5767937_960_720.jpg",
                "https://cdn.pixabay.com/photo/2021/01/10/12/00/road-5904909_640.jpg"
            )
        )
    }
}

3. ImageSliderAdapter.kt

package com.piashcse.experiment.viewpager2withrvadapter.adapter

import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.piashcse.experiment.viewpager2withrvadapter.databinding.ImageSliderItemLayoutBinding

class ImageSliderAdapter: RecyclerView.Adapter<ImageSliderAdapter.ImageViewHolder>() {
    private var items = ArrayList<String>()
    private var onItemClick: ((String) -> Unit)? = null

    fun addItem(newItems: List<String>?) {
        newItems?.let {
            items.addAll(newItems)
            notifyDataSetChanged()
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ImageViewHolder {
        val inflater = LayoutInflater.from(parent.context)
        val binding = ImageSliderItemLayoutBinding.inflate(inflater, parent, false)
        return ImageViewHolder(binding)
    }

    override fun getItemCount() = items.size

    override fun onBindViewHolder(holder: ImageViewHolder, position: Int) {
        val image = items[position]
        return holder.bind(image)
    }

    inner class ImageViewHolder(private val bind: ImageSliderItemLayoutBinding) : RecyclerView.ViewHolder(bind.root) {
        fun bind(item: String) {
            bind.item = item
            bind.executePendingBindings()
            itemView.setOnClickListener {
                onItemClick?.invoke(item)
            }
        }
    }
}

4. image_slider_item_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="item"
            type="java.lang.String" />
    </data>
    <androidx.appcompat.widget.LinearLayoutCompat
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <androidx.appcompat.widget.AppCompatImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            loadSliderImage='@{item}'/>

    </androidx.appcompat.widget.LinearLayoutCompat>
</layout>

5. default_indicator_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape
            android:innerRadius="0dp"
            android:shape="ring"
            android:thickness="3dp"
            android:useLevel="false">
            <solid android:color="@color/material_white"/>
        </shape>
    </item>
</layer-list>

6. selected_indicator_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape
            android:innerRadius="0dp"
            android:shape="ring"
            android:thickness="3dp"
            android:useLevel="false">
            <solid android:color="@color/material_amber900"/>
        </shape>
    </item>
</layer-list>

7. pager_indicator.xml

<?xml version="1.0" encoding="utf-8"?>
<selector
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/selected_indicator_dot"
        android:state_selected="true"/>
    <item android:drawable="@drawable/default_indicator_dot"/>
</selector>

Github:https://github.com/piashcse/blog_piashcse_code/tree/master/ViewPager2WithRvAdapter
Medium:https://piashcse.medium.com/viewpager2-with-recyclerview-adapter-b048f625a208

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Android color opacity Hexadecimal values

• These two values have to add as a prefix in android color code and it will be transparent as given percentage below: 

100% — FF
99% — FC
98% — FA
97% — F7
96% — F5
95% — F2
94% — F0
93% — ED
92% — EB
91% — E8

90% — E6
89% — E3
88% — E0
87% — DE
86% — DB
85% — D9
84% — D6
83% — D4
82% — D1
81% — CF

80% — CC
79% — C9
78% — C7
77% — C4
76% — C2
75% — BF
74% — BD
73% — BA
72% — B8
71% — B5

70% — B3
69% — B0
68% — AD
67% — AB
66% — A8
65% — A6
64% — A3
63% — A1
62% — 9E
61% — 9C

60% — 99
59% — 96
58% — 94
57% — 91
56% — 8F
55% — 8C
54% — 8A
53% — 87
52% — 85
51% — 82

50% — 80
49% — 7D
48% — 7A
47% — 78
46% — 75
45% — 73
44% — 70
43% — 6E
42% — 6B
41% — 69

40% — 66
39% — 63
38% — 61
37% — 5E
36% — 5C
35% — 59
34% — 57
33% — 54
32% — 52
31% — 4F

30% — 4D
29% — 4A
28% — 47
27% — 45
26% — 42
25% — 40
24% — 3D
23% — 3B
22% — 38
21% — 36

20% — 33
19% — 30
18% — 2E
17% — 2B
16% — 29
15% — 26
14% — 24
13% — 21
12% — 1F
11% — 1C

10% — 1A
9% — 17
8% — 14
7% — 12
6% — 0F
5% — 0D
4% — 0A
3% — 08
2% — 05
1% — 03
0% — 00 

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