Adarsh Patel

Android Kotlin Tutorial Day 2

Learning Objective: Let’s start playing with Kotlin Language and do some basic operations like on button click display toast message to users, take input from edit text and display in textview and more.

Button Click Event – Display Toast Message

 override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        binding.btnclickme.setOnClickListener {

            Toast.makeText(context, "Hello I am Toast :)", Toast.LENGTH_SHORT).show()
        }
    }

Read EditText Value > Convert to Integer and Do Sum

 binding.btnsum.setOnClickListener {

            var no1 = binding.et1.text.toString();
            var no2 = binding.et2.text.toString();
            var sum = no1.toInt() + no2.toInt();

            binding.tvresult.text = sum.toString();
        }

Layout Code for above ones

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".FirstFragment">


    <Button
        android:id="@+id/btnclickme"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click me" />

    <EditText
        android:id="@+id/et1"
        android:hint="Enter Number 1 "
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>


    <EditText
        android:id="@+id/et2"
        android:hint="Enter Number 2 "
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/btnsum"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Sum" />

    <TextView
        android:id="@+id/tvresult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

Move from FirstFragment to SecondFragment after 5 Seconds

   Handler().postDelayed({
            findNavController().navigate(R.id.action_FirstFragment_to_SecondFragment)

        }, 5000)

Android Kotlin Tutorial Day 3

Learning Objective: Let’s try some most important codes like saving data into SharedPreference using Kotlin, Call Online API, and Display Static value into ListView.

SharedPreference Example

val sharedpreferences = requireContext().getSharedPreferences(
                MyPREFERENCES,
                Context.MODE_PRIVATE
            )
            val name = "Adarsh"
            val editor = sharedpreferences.edit()
            editor.putString("name", name)
            editor.commit()
            Toast.makeText(context, "Pref Saved", Toast.LENGTH_SHORT).show()

Call API Online

fun callAPI() {

        // Instantiate the RequestQueue.
        val queue: RequestQueue = Volley.newRequestQueue(context)
        val url = "https://jsonplaceholder.typicode.com/todos/1"


        // Request a string response from the provided URL.
        val stringRequest = StringRequest(
            Request.Method.GET, url,
            Response.Listener<String> { response ->

                    Log.e("cs", response)
                    try {
                        val obj = JSONObject(response)
                        Log.e("cs", obj.getString("userId"))
                        Log.e("cs", obj.getString("id"))
                        Log.e("cs", obj.getString("title"))
                        Log.e("cs", obj.getString("completed"))
                    } catch (t: Throwable) {
                        Log.e("cs", "Could not parse malformed JSON: \"" + "" + "\"")
                    }
            }, object : Response.ErrorListener {
                override fun onErrorResponse(error: VolleyError) {
                    Log.e("cs", error.toString())
                }
            })

        // Add the request to the RequestQueue.
        queue.add(stringRequest)
    }

ListView Display Items

fragment_second.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".SecondFragment">

    <!-- TODO: Update blank fragment layout -->

    <ListView
        android:id="@+id/list1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>


</LinearLayout>

SecondFragment.kt

package com.example.kotlin1

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import android.widget.ListView
import androidx.fragment.app.Fragment
import com.example.kotlin1.databinding.FragmentSecondBinding


/**
 * A simple [Fragment] subclass as the second destination in the navigation.
 */
class SecondFragment : Fragment() {

    private var _binding: FragmentSecondBinding? = null
    var list1: ListView? = null
    var courses = arrayOf("BCA", "PGDCA", "MCA", "MBA")

    // This property is only valid between onCreateView and
    // onDestroyView.
    private val binding get() = _binding!!

    override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {

        val view: View = inflater.inflate(R.layout.fragment_second, container, false)

        list1 = view.findViewById<View>(R.id.list1) as ListView
        val arr1: ArrayAdapter<String>

        arr1 = ArrayAdapter(
            requireContext(),
            androidx.appcompat.R.layout.support_simple_spinner_dropdown_item,
            courses
        )
        list1!!.adapter = arr1

        // Inflate the layout for this fragment

        // Inflate the layout for this fragment
        return view
       /* _binding = FragmentSecondBinding.inflate(inflater, container, false)
        return binding.root*/

    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

       /* binding.buttonSecond.setOnClickListener {
            findNavController().navigate(R.id.action_SecondFragment_to_FirstFragment)
        }*/
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}