AkaashSaini

Pre-defined Functions
String functions
The string is represent by 
	“ABC”
		or
	‘ABC’
Functions – 
a.	strlen($str) – it returns the length of string.

<?php

AkaashSaini

Recycle View
It allocates memory for only those elements which are visible on screen. On scroll of screen it automatically refreshes the memory.

Step 1
Add Dependency for RecyclerView to gradle file
It already exists
implementation 'com.android.support:appcompat-v7:28.0.0-beta01'

add this line using the version of above line

AkaashSaini

Fetching data from Table
Step 1 - Create following table in database android
	Student(name,branch,roll)
Insert some records

Step 2 – Create PHP file to select data (show_students.php)
	<?php
$cn=mysqli_connect("localhost","root","","android");
if(!$cn)
{

AkaashSaini

SharedPrefereces 
It is used to maintain parameters and values. These parameters can be used by any activity of application. So it can be used to pass parameters and there values from one activity to other.
Create editor from shared preferences.
SharedPreferences sp = getSharedPreferences("mypref", MODE_PRIVATE);
Editor editor=sp.edit()
Put some parameters
editor.clear(); 
editor.putString("name", "Elena"); // first is parameter and second is value
 editor.putInt("idName", 12);
 editor.commit();

AkaashSaini

Confirm Dialog
We can use Confirm Dialog of JavaScript in PHP. It is very useful when we try to perform sensitive data operation. Using it we can confirm before do operation on data like delete operation on data.
Example 1
<form 
	method="post" 
	action="delete_record.php" 
	onSubmit="return confirm('Do you want to delete?')">

    <input type="submit" name="B1" value="Delete" />
</form>

AkaashSaini

Using Cookie
A cookie is a small text file that lets you store a small amount of data (nearly 4KB) on the user's computer.
It is used to 
•	control access of pages, 
•	keep track of user info
Each time the browser requests a page from the server, all the data in the cookie is automatically sent to the server with the request.
Step 1
Create cookie using function
	setcookie(name, value, expire, path, domain, secure);
	name Parameter name

AkaashSaini

Using Password Encryption
The general function md5() is used to create hash key of string. It takes the string input and produces 128 bit fingerprint. 

To insert in database using following code
$email=$_POST["T1"];
	$password=$_POST["T2"];
	require_once("MyLib.php");
	$pass=md5($password);
	//echo $pass; die();
	$sql="insert into logindata values('$email','$pass')";

AkaashSaini

Volley – Fetch Data as JSON
•	Create following PHP script

<?php
$cn=mysqli_connect("localhost","root","","android");
if(!$cn)
{
	echo "Unable to connect";
	die();
}

AkaashSaini

Volley – Save Data
Volley is an HTTP library that makes networking for Android apps easier and most importantly, faster. It was developed by google and introduced in 2013. It is available as AOSP (Android Open Source Repository)
Volley is available on GitHub.
Volley offers the following benefits:
•	Automatic scheduling of network requests.
•	Multiple concurrent network connections.
•	Transparent disk and memory response caching with standard HTTP cache coherence.
•	Support for request prioritization.
•	Cancellation request API. You can cancel a single request, or you can set blocks or scopes of requests to cancel.
•	Ease of customization, for example, for retry and backoff.

AkaashSaini

activity_main.xml
<TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click the button to go to pip mode!"
        android:textColor="@color/black"
        android:textSize="20dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"