Activity loads independently but not in Fragment - android-fragments

Question

I am new to Mobile development. I have started my Mobile app with Kotlin. I have an Activity (ProductsActivity.kt) which loads RecyclerView with ImageView and TextView getting data from MySQL, which is working independently. Now, I want this Activity to load in Fragment, I tried to load using Inflater, but it doesn't show any data. Following is my code, please help how can I achieve the same. Thanks in advance.
MainActivity.kt
package com.example.administrator.zmaart
import android.content.Intent
import android.os.Bundle
import android.support.design.widget.NavigationView
import android.support.v4.app.Fragment
import android.support.v4.view.GravityCompat
import android.support.v4.widget.DrawerLayout
import android.support.v7.app.ActionBarDrawerToggle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.Toolbar
import android.view.Menu
import android.view.MenuItem
import android.view.View
import android.widget.Toast
class MainActivity : AppCompatActivity(),
NavigationView.OnNavigationItemSelectedListener {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val toolbar = findViewById<View>(R.id.toolbar) as Toolbar
setSupportActionBar(toolbar)
val drawer = findViewById<View>(R.id.drawer_layout) as DrawerLayout
val toggle = ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open,
R.string.navigation_drawer_close)
drawer.addDrawerListener(toggle)
toggle.syncState()
val navigationView = findViewById<View>(R.id.nav_view) as
NavigationView
navigationView.setNavigationItemSelectedListener(this)
displaySelectedScreen(R.id.nav_home)
}
private var backButtonCount: Int = 0
override fun onBackPressed() {
val drawer = findViewById<View>(R.id.drawer_layout) as DrawerLayout
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START)
} else {
if (backButtonCount >= 1) {
val intent = Intent(Intent.ACTION_MAIN)
intent.addCategory(Intent.CATEGORY_HOME)
intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK
startActivity(intent)
} else {
Toast.makeText(this, "Press the back button once again to close the application.", Toast.LENGTH_SHORT).show()
backButtonCount++
}
}
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
// Inflate the menu; this adds items to the action bar if it is present.
menuInflater.inflate(R.menu.main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
val id = item.itemId
return if (id == R.id.action_settings) {
true
} else super.onOptionsItemSelected(item)
}
override fun onNavigationItemSelected(item: MenuItem): Boolean {
displaySelectedScreen(item.itemId)
return true
}
private fun displaySelectedScreen(itemId: Int) {
//creating fragment object
var fragment: Fragment? = null
//initializing the fragment object which is selected
when (itemId) {
R.id.nav_home -> fragment = home()
R.id.nav_orders -> fragment = orders()
R.id.nav_wishlist -> {
val intent = Intent(this#MainActivity,
ProductsActivity::class.java)
this#MainActivity.startActivity(intent)
}
R.id.nav_logout -> {
val sharedPreferences = getSharedPreferences("SharedPref", 0)
val editor = sharedPreferences.edit()
editor.clear()
editor.apply()
val intent = Intent(this#MainActivity, Login_Page::class.java)
this#MainActivity.startActivity(intent)
}
}
//replacing the fragment
if (fragment != null) {
val ft = supportFragmentManager.beginTransaction()
ft.replace(R.id.content_frame, fragment)
ft.commit()
}
val drawer = findViewById<View>(R.id.drawer_layout) as DrawerLayout
drawer.closeDrawer(GravityCompat.START)
}
}
activity_products.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
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=".ProductsActivity">
<android.support.v7.widget.RecyclerView
android:id="#+id/recylcerView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteX="745dp"
tools:layout_editor_absoluteY="-51dp" />
</RelativeLayout>
ProductsActivity.kt
package com.example.administrator.zmaart
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.LinearLayoutManager
import android.support.v7.widget.RecyclerView
import com.android.volley.Request
import com.android.volley.Response
import com.android.volley.toolbox.StringRequest
import com.android.volley.toolbox.Volley
import org.json.JSONArray
import org.json.JSONException
import java.util.*
class ProductsActivity : AppCompatActivity() {
private lateinit var productList: MutableList<Product>
private lateinit var recyclerView: RecyclerView
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_products)
recyclerView = findViewById(R.id.recylcerView1)
recyclerView.setHasFixedSize(false)
recyclerView.layoutManager = LinearLayoutManager(this)
productList = ArrayList()
loadProducts()
}
private fun loadProducts() {
/*
* Creating a String Request
* The request type is GET defined by first parameter
* The URL is defined in the second parameter
* Then we have a Response Listener and a Error Listener
* In response listener we will get the JSON response as a String
* */
val stringRequest = StringRequest(Request.Method.GET, URL_PRODUCTS,
Response.Listener { response ->
try {
//converting the string to json array object
val array = JSONArray(response)
//traversing through all the object
for (i in 0 until array.length()) {
//getting product object from json array
val product = array.getJSONObject(i)
//adding the product to product list
productList.add(Product(
product.getString("prod_id_sha"),
product.getString("prod_title"),
product.getDouble("prod_price"),
product.getDouble("prod_price2"),
product.getString("img_thumbnail")
))
}
//creating adapter object and setting it to recyclerview
val adapter = ProductsAdapter(this#ProductsActivity, productList)
recyclerView.adapter = adapter
} catch (e: JSONException) {
e.printStackTrace()
}
},
Response.ErrorListener { })
//adding our stringrequest to queue
Volley.newRequestQueue(this).add(stringRequest)
}
companion object {
//this is the JSON Data URL
//make sure you are using the correct ip else it will not work
private const val URL_PRODUCTS = "localhost/app/load_prod.php"
}
}
home.kt (where I want to load activity_products.xml)
package com.example.administrator.zmaart
import android.os.Bundle
import android.support.v4.app.Fragment
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
class home : Fragment() {
private lateinit var productList: MutableList<Product>
private lateinit var recyclerView: RecyclerView
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.activity_products, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
activity!!.title = "Home"
}
}
Please let me know if any other code(s) to be included to help you to help me.