MainActivity.kt
---------------
package com.example.stsearch

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.AdapterView
import android.widget.ArrayAdapter
import android.widget.Spinner
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

        var fossVsFossID = HashMap<String, Int>()
        fossVsFossID.put("Java",10)
        fossVsFossID.put("Cpp",57)
        fossVsFossID.put("Python",26)
        fossVsFossID.put("RDBMS",92)

        var languageVsLanguageID = HashMap<String, Int>()
        languageVsLanguageID.put("English", 22)
        languageVsLanguageID.put("Hindi", 6)
        languageVsLanguageID.put("Gujarati", 5)
        languageVsLanguageID.put("Tamil", 18)
        languageVsLanguageID.put("Marathi", 12)
        languageVsLanguageID.put("Kannada", 7)

        var fossVsLanguage = HashMap<String, ArrayList<String>>()
        var availableLanguagesForFoss: ArrayList<String>

        availableLanguagesForFoss = arrayListOf("English", "Gujarati","Hindi",  "Kannada")
        fossVsLanguage.put("Java", availableLanguagesForFoss)

        availableLanguagesForFoss = arrayListOf("English", "Gujarati", "Hindi","Kannada", "Marathi", "Tamil")
        fossVsLanguage.put("Cpp", availableLanguagesForFoss)

        availableLanguagesForFoss = arrayListOf("English", "Hindi")
        fossVsLanguage.put("Python", availableLanguagesForFoss)

        availableLanguagesForFoss = arrayListOf("English")
        fossVsLanguage.put("RDBMS", availableLanguagesForFoss)

        var fossSpinner = findViewById<Spinner>(R.id.Spinner1)
        var languageSpinner = findViewById<Spinner>(R.id.Spinner2)

        var fossOptions = fossVsFossID.keys.toList()
        var languageOptions = languageVsLanguageID.keys.toMutableList()

        var selectedFoss = "none"
        var selectedLanguage = "none"
        var fossAdapter = ArrayAdapter<String>(applicationContext, android.R.layout.simple_list_item_activated_1, fossOptions)
        fossSpinner.adapter = fossAdapter

        var languageAdapter = ArrayAdapter<String>(applicationContext, android.R.layout.simple_list_item_activated_1, languageOptions)

        languageSpinner.adapter = languageAdapter

        fossSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onNothingSelected(parent: AdapterView<*>?) {
            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {

                languageOptions.clear()

                selectedFoss = fossOptions.get(position)

                languageOptions.addAll(ArrayList(fossVsLanguage.get(selectedFoss)!!))

                languageAdapter.notifyDataSetChanged()
            }
        }

        languageSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onNothingSelected(parent: AdapterView<*>?) {
            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {

                selectedLanguage = languageOptions.get(position)
            }
        }

        searchButton.setOnClickListener {
            if (selectedFoss == "none" || selectedLanguage == "none") {

                Toast.makeText(this, "Please select FOSS and Language both", Toast.LENGTH_SHORT).show()

            } else {

                var fossID = fossVsFossID.get(selectedFoss)
                var languageID = languageVsLanguageID.get(selectedLanguage)

                var searchIntent = Intent(this, Main2Activity::class.java).apply {
                    putExtra("fossID", "" + fossID)
                    putExtra("languageID", "" + languageID)
                }
                startActivity(searchIntent)
            }

        }

    }
}
-------------------------------------------------------------------------------

Main2Activity.kt
----------------
package com.example.stsearch

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.android.volley.Request
import com.android.volley.Request.*
import com.android.volley.Response
import com.android.volley.toolbox.StringRequest
import com.android.volley.toolbox.Volley
import kotlinx.android.synthetic.main.activity_main2.*
import org.json.JSONArray
import org.json.JSONObject

class Main2Activity : AppCompatActivity() {
    var finalResultsArrayList = ArrayList<VideoItem>()
    lateinit var myAdapter: MyAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main2)

        var foss = intent.getStringExtra("fossID")
        var language = intent.getStringExtra("languageID")
        selectedOption.text = "Foss ID : " + foss + "\nLanguage ID : " + language

        var myRecyclerView = findViewById<RecyclerView>(R.id.videos_recyclerview)

        myAdapter = MyAdapter(applicationContext, finalResultsArrayList)

        myRecyclerView.layoutManager = LinearLayoutManager(this)
        myRecyclerView.setHasFixedSize(true)
        myRecyclerView.adapter = myAdapter



        val queue = Volley.newRequestQueue(this)
        val url = "https://spoken-tutorial.org/api/get_tutorials/" + foss+ "/" + language


        val stringRequest = StringRequest(Request.Method.GET, url, Response.Listener<String> { response ->

            Toast.makeText(applicationContext,"Received server response!", Toast.LENGTH_SHORT).show()

            extractJsonData(response)

        }, Response.ErrorListener {
            Toast.makeText(applicationContext, "Unable to connect to the server", Toast.LENGTH_SHORT).show()
        })
        Toast.makeText(applicationContext,
            "Contacting Server...", Toast.LENGTH_SHORT).show()
        queue.add(stringRequest)

    }

    private fun extractJsonData(jsonResponse: String) {
        var videosDataArray = JSONArray(jsonResponse)
        var singleVideoJsonObject: JSONObject
        var singleVideoItem: VideoItem
        var i = 0
        var size = videosDataArray.length()

        while (i < size) {
            singleVideoJsonObject = videosDataArray.getJSONObject(i)
            singleVideoItem =
                VideoItem(singleVideoJsonObject.getString("video_id"),
                    singleVideoJsonObject.getString("tutorial_name"),
                    singleVideoJsonObject.getString("tutorial_level"))
            finalResultsArrayList.add(singleVideoItem)
            i++
        }
        println("The parsed videoItems are :")
        finalResultsArrayList.forEach { println(it) }
        myAdapter.notifyDataSetChanged()

    }
}

------------------------------------------------------------------------------------------
ThirdActivity.kt
----------------
package com.example.stsearch

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast

class ThirdActivity : AppCompatActivity() {

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

        var selectedVideoID = intent.getStringExtra("VIDEO_ID")
        var selectedVideoTitle =
            intent.getStringExtra("VIDEO_TITLE")

        Toast.makeText(applicationContext,""+ selectedVideoTitle,
            Toast.LENGTH_SHORT).show()
    }
}

------------------------------------------------------------------------------------------------
MyAdapter.kt
-------------
package com.example.stsearch

import android.content.Context
import android.content.Intent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.squareup.picasso.Picasso
import kotlinx.android.synthetic.main.my_customlayout.view.*



class MyAdapter
    (val mContext : Context, val videoList : ArrayList<VideoItem>) :
    RecyclerView.Adapter<MyAdapter.MyViewHolder>(){
    class MyViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView)

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {

        val layoutInflator = LayoutInflater.from(parent.context)
        val videoItem = layoutInflator.inflate(R.layout.my_customlayout, parent, false)

        return MyViewHolder(videoItem)
    }
    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {

        var singleVideoItem = videoList.get(position)

        holder.itemView.video_title.text = singleVideoItem.videoTitle
        holder.itemView.video_level.text = "Level : " + singleVideoItem.videoLevel

        Picasso.with(mContext)
            .load("https://i.ytimg.com/vi/"+singleVideoItem.videoId+"/sddefault.jpg")
            .resize(640,360)//640x360   *initially 320x180
            .centerCrop()
            .into(holder.itemView.video_thumbnail)

        holder.itemView.itemLinearLayout.setOnClickListener{

            var playVideoIntent = Intent(mContext, ThirdActivity::class.java).apply {
                putExtra("VIDEO_ID",""+singleVideoItem.videoId)
                putExtra("VIDEO_TITLE",""+singleVideoItem.videoTitle)
                addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
            }

            mContext.startActivity(playVideoIntent)
        }
    }

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

}

--------------------------------------------------------------------------------------------
Run Log file
------------
Run logfile
-----------

06/23 06:33:33: Launching app
$ adb push /home/rsenthilkumar/STsearch/app/build/outputs/apk/debug/app-debug.apk /data/local/tmp/com.example.stsearch
$ adb shell pm install -t -r "/data/local/tmp/com.example.stsearch"
Success
APK installed in 18 s 61 ms
$ adb shell am start -n "com.example.stsearch/com.example.stsearch.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Client not ready yet..Waiting for process to come online
Connected to process 26355 on device lge-lm_x210-LMX210bcbfde07
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter androidx.vectordrawable.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
W/art: Before Android 4.1, method int androidx.appcompat.widget.DropDownListView.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
I/Adreno-EGL: <qeglDrvAPI_eglInitialize:379>: EGL 1.4 QUALCOMM build: Nondeterministic_AU_msm8909_LA.BR.1.2.9_RB1__release_AU (I09d312ff84)
    OpenGL ES Shader Compiler Version: E031.31.00.01
    Build Date: 09/25/17 Mon
    Local Branch:
    Remote Branch: quic/LA.BR.1.2.9_rb1.26
    Local Patches: NONE
    Reconstruct Branch: NOTHING
I/OpenGLRenderer: Initialized EGL, version 1.4
D/OpenGLRenderer: Swap behavior 1
I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@d0a84c0 time:2076235
D/ViewRootImpl: Need to measure again cause of requestLayout called between measure and layout
I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@d0a84c0 time:2112300
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
I/AudioManagerEx: AudioManagerEx created
D/OpenGLRenderer: endAllActiveAnimators on 0x95ed6000 (DropDownListView) with handle 0xaad99c70
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
D/OpenGLRenderer: endAllActiveAnimators on 0x95ed9800 (DropDownListView) with handle 0xab629cc0
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
I/AudioManagerEx: AudioManagerEx created
I/Timeline: Timeline: Activity_launch_request id:com.example.stsearch time:2117599
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.stsearch, PID: 26355
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.stsearch/com.example.stsearch.Main2Activity}: java.lang.IllegalStateException: myRecyclerView must not be null
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2763)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2824)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1546)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6351)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:896)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:786)
     Caused by: java.lang.IllegalStateException: myRecyclerView must not be null
        at com.example.stsearch.Main2Activity.onCreate(Main2Activity.kt:33)
        at android.app.Activity.performCreate(Activity.java:6775)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2716)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2824)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1546)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6351)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:896)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:786)
Application terminated.