Android Kotlin CURD Operation using Volley

Google announced at I/O 2017 that it will officially support Kotlin as a first language for Android Development.Kotlin tools will be included with Android Studio 3.0. Kotlin is easy to get started with and can be gradually introduced into existing projects, which means that your existing skills and technology investments are preserved. Kotlin was named after an island (Kotlin Island, located nearby the city of Saint-Petersburg).

What is Kotlin ?

Kotlin is powerful language primarily developed by JetBrains Team. It runs on JVM (Java Virtual Machine) and is statically typed programming language (statically-typed languages require you to declare the data types of your variables before you use them) and also can be compiled to JavaScript source code or uses the Low level Virtual Machine compiler infrastructure. It is perfect for Android Development because of Compatibility with Java , Performance (uses byteCode Structure), Interoperability (import java libraries). Kotlin extention is .kt.

Advantages of using Kotlin :

• Kotlin requires less code to write.
• Less Crushes occur on Kotlin.
• Kotlin is Type-safety Language.
• Kotlin saves time.

Demo Video

 

Lets Get started with Kotlin

Before starting download the preview version of Android Studio 3.0.

Step 1. Create Project

Type your Project Name -> Check Include Kotlin Support -> Click Next

Step 2. Select the Version Minimum SDK

Step 3. Click on Empty Activity

 

Add this to your Gradle File

Dont compile Kotlin if it is already there in Gradle File

 compile 'com.android.volley:volley:1.0.0' 
 compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"

Add this to your Manifest File

<uses-permission android:name="android.permission.INTERNET"/>

 

Step 4. Creating Database Structure

Step 5. Writing Connection File

As you have to establish a connection for you database you have to make connection.php file . Run this file on the server you can use XAMPP or WAMP for the local server if you are getting blank screen it means that your connection is established.

<?php
$server_name = "localhost"; //servername

$user_name = "root1"; //username

$password = "root1"; //password

$db= 'freebieslearning'; //database name

$conn = mysqli_connect($server_name, $user_name, $password,$db);
if(!$conn){

die("Error Connection");

}
?>

Step 6. Writing Employee file


Use this URL to check your Inserted Data

<?PHP
include("Connection.php");
if(isset($_POST['name']) && isset($_POST['position'])&& isset($_POST['salary'])&& isset($_POST['experience']))

{

$name = $_POST["name"];
  $position = $_POST["position"];

  $salary = $_POST["salary"];

  $experience = $_POST["experience"];

  $query="INSERT INTO employee(name,position,salary,experience)VALUES('$name','$position','$salary','$experience')";

  $data=mysqli_query($conn,$query);

if($data)
  {
        echo "Data Inserted";
  }
else
  {
        echo "Error While Inserting";
  }

    exit;

}
?>

Step 7. Creating XML Layout

<?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:gravity="center"
    android:orientation="vertical"
    tools:context="com.example.sumit.volley_crud_operations.MainActivity">
&lt;ImageView
    android:id="@+id/imageView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:srcCompat="@drawable/kotlin" /&gt;

&lt;LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="10dp"
    android:orientation="vertical"&gt;

    &lt;TextView
        android:id="@+id/textView3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10dp"
        android:background="@color/colorPrimaryDark"
        android:gravity="center"
        android:padding="5dp"
        android:text="@string/employee_Details"
        android:textColor="@android:color/background_light"
        android:textSize="18sp" /&gt;

    &lt;EditText
        android:id="@+id/editTextName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/enter_name" /&gt;

    &lt;EditText
        android:id="@+id/editTextPosition"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/position"
        android:inputType="textPersonName" /&gt;

    &lt;EditText
        android:id="@+id/editTextSalary"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/salary"
        android:inputType="textPersonName" /&gt;


    &lt;EditText
        android:id="@+id/editTextExperience"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/years"
        android:inputType="textPersonName" /&gt;

    &lt;Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        android:singleLine="true"
        android:text="@string/send_button"
        android:textColor="@android:color/background_light" /&gt;

&lt;/LinearLayout&gt;

</LinearLayout>

Step 8 . Writing Kotlin File
package com.example.sumit.volley_crud_operations
import android.app.Activity

import android.app.ProgressDialog

import android.content.Intent

import android.support.v7.app.AppCompatActivity

import android.os.Bundle

import android.util.Log

import android.view.View

import android.widget.Button

import android.widget.EditText

import android.widget.Toast

import com.android.volley.DefaultRetryPolicy

import com.android.volley.Request

import com.android.volley.Response

import com.android.volley.toolbox.StringRequest

import com.android.volley.toolbox.Volley
class MainActivity : AppCompatActivity() {
// Variable declaration

private var editTextName: EditText? = null
private var editTextPosition: EditText? = null
private var editTextSalary: EditText? = null
private var editTextExperience: EditText? = null
private var button: Button? = null
private var pd: ProgressDialog? = null

//URL

private val URL = "http://vga.ramstertech.com/freebieslearning/employee.php"

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

    pd = ProgressDialog(this@MainActivity)

//Accessing Palette from XML in Kotlin
    editTextName = findViewById(R.id.editTextName) as EditText

    editTextPosition = findViewById(R.id.editTextPosition) as EditText

    editTextSalary = findViewById(R.id.editTextSalary) as EditText

    editTextExperience = findViewById(R.id.editTextExperience) as EditText

    button = findViewById(R.id.button) as Button

    // onClickListener

    button?.setOnClickListener(View.OnClickListener {

        loginRequest()
    })
}

// Method for Inserting data using Volley
private fun loginRequest() {

    pd!!.setMessage("Inserting Data . . ")

    pd!!.show()

    val queue = Volley.newRequestQueue(this@MainActivity)

    val response: String? = null

    val finalResponse = response

    val postRequest = object : StringRequest(Request.Method.POST, URL,Response.Listener&lt;String&gt;
    {
        
// Getting Response from Server
        
        response -&gt;

        pd!!.hide()
        
//Toast Method
        
        toast(response)
        
//Remove Method 
        
        remove()

    },
      Response.ErrorListener {
           // error
           pd!!.hide()
           Log.d("ErrorResponse", finalResponse)
      }
    ) {
        override fun getParams(): Map&lt;String, String&gt; {
            //Creating HashMap
            val params = HashMap&lt;String, String&gt;()

            params.put("name", editTextName?.text.toString())
            params.put("position", editTextPosition?.text.toString())
            params.put("salary", editTextSalary?.text.toString())
            params.put("experience", editTextExperience?.text.toString())

            return params
        }
    }

    postRequest.retryPolicy = DefaultRetryPolicy(0, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT)

    queue.add(postRequest)


}

//Method for Toast

fun Activity.toast(setToast: CharSequence) {
    Toast.makeText(this, setToast, Toast.LENGTH_SHORT).show()
}

//Method for clear Text After Sending Data to the server

private fun remove(){
    editTextName?.text?.clear()
    editTextPosition?.text?.clear()
    editTextExperience?.text?.clear()
    editTextSalary?.text?.clear()

}

}

 
Run you project Now. Always use LogCat to debug your Applications.