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

Volley – Fetch Data as JSON
•	Create following PHP script

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

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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')";

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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

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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>

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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();

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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)
{

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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

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

<?php

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      Fragments
      A Fragment is a piece of an activity which enable more modular activity design. It will not be wrong if we say, a fragment is a kind of sub-activity.
      •	A fragment has its own layout and its own behaviour with its own life cycle callbacks.
      •	You can add or remove fragments in an activity while the activity is running.
      •	You can combine multiple fragments in a single activity to build a multi-plane UI.
      •	A fragment can be used in multiple activities.
      •	Fragment life cycle is closely related to the life cycle of its host activity which means when the activity is paused, all the fragments available in the activity will also be stopped.
      •	A fragment can implement a behaviour that has no user interface component.
      •	Fragments were added to the Android API in Honeycomb version of Android which API version 11.