Coding Redefined | Sample Code & Tutorials

Sunday, 25 March 2018

OOPs Concepts

Although its actually OOP concepts, but the most widely used term is OOPs Concepts. Though OOP stands for Object Oriented Programming, but what what does "s" stands for? System. "s" in OOPs stands for Object Oriented Programming System.

Lets talk about OOP concepts, the basics of all Programming Languages available today.

Abstraction
Encapsulation
Polymorphism
Inheritence

Abstraction

Abstraction is the concept of hiding the internal processing from outside world. We can implement abstraction using encapsulation and inheritance.

Encapsulation

Encapsulation is a means to achieve Abstraction. it is used to restrict the scope and usage of class members and methods. Access modifiers such as public, private and protected are used to restrict access.

Polymorphism

Polymorphism is a concept in which an object can behave differently based on different situations.
Polymorphism can further be classified into 2 categories, i.e. Run time Polymorphism, and Compile time polymorphism.

Inheritance
Inheritance is a means to achieve code reusability. It allows the properties of another class to be used in another class in a Parent-Child model. The class using the properties of another class is called the Derived class and the class whose properties are used by another class are called Base Class or Parent Class. Inheritance in Java is achieved using keyword "extends".
Types of Inheritance(in Java): Single Inheritance, Multilevel Inheritance, and Hybrid Inheritance

Friday, 16 March 2018

Sort HTML Table using JavaScript

Here is how you can sort your HTML data using a simple Javascript function WITHOUT using any external library.

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Sort Table using Javascript</title>

<script type="text/javascript">

/*
* These variables as name suggests store the column index based on
* which the table wil be sorted and also the sorting order
*/
var sortOrder;
var sortColumn;

function sortTable(column) {

/*
* First we will determine if the user has clicked the table for first
* time indicating that the table should be sorted in Ascending order. If
* user has clicked on it second time, then table will be sorted in
* descending order.
*/
if (sortColumn != column) {
sortColumn = column;
sortOrder = "asc";
} else if (sortColumn == column && sortOrder == "asc") {
sortOrder = "desc";
} else if (sortColumn == column && sortOrder == "desc") {
sortOrder = "asc";
}

var tableData = document.getElementById("myTable");
//This variable stores the complete Table Data
var tableRows = tableData.rows;

// Here we will convert the table data into an array for easy processing
var sortDataArray = [];
for (index = 1; index < tableRows.length; index++) {
sortDataArray.push(tableRows[index]);
}

/*
* Here we will pass the data array along with the column index, and
* sorting order to the data sorting algorithm. Here Merge Sort algorithm
* is being used to sort data.
*/
mergeSort(sortDataArray, 0, sortDataArray.length - 1, sortColumn,
sortOrder);

/*
* And Voila, sorting algorithm has sorted the data and returned data in a sorted array.
* Now all that's left is to set the sorted table data back into the html table.
*/
var sortedTableBody = "";
for (rowIndex = 0; rowIndex < sortDataArray.length; rowIndex++) {
sortedTableBody += "<tr>";
var rowCells = sortDataArray[rowIndex].cells;
for (columnIndex = 0; columnIndex < rowCells.length; columnIndex++) {
sortedTableBody += "<td>" + rowCells[columnIndex].innerHTML
+ "</td>";
}
sortedTableBody += "</tr>";

}

document.getElementById("myTableBody").innerHTML = sortedTableBody;
}

function mergeSort(arr, l, r, sortColumn, sortOrder) {

if (l < r) {
var m = Math.floor(l + (r - l) / 2);

mergeSort(arr, l, m, sortColumn, sortOrder);
mergeSort(arr, m + 1, r, sortColumn, sortOrder);

merge(arr, l, m, r, sortColumn, sortOrder);
}

}

function merge(arr, l, m, r, sortColumn, sortOrder) {

var i;
var j;
var k;
var n1 = m - l + 1;
var n2 = r - m;

var L = [];
var R = [];

for (i = 0; i < n1; i++) {
L[i] = arr[l + i];
}

for (j = 0; j < n2; j++) {
R[j] = arr[m + 1 + j];
}

i = 0;
j = 0;
k = l;
if (sortOrder == "asc") {
while (i < n1 && j < n2) {
if (L[i].cells[sortColumn].innerHTML <= R[j].cells[sortColumn].innerHTML) {
arr[k] = L[i];
i++;
} else {
arr[k] = R[j];
j++;
}
k++;
}
} else if (sortOrder == "desc") {
while (i < n1 && j < n2) {
if (L[i].cells[sortColumn].innerHTML >= R[j].cells[sortColumn].innerHTML) {
arr[k] = L[i];
i++;
} else {
arr[k] = R[j];
j++;
}
k++;
}
}

while (i < n1) {
arr[k] = L[i];
i++;
k++;
}

while (j < n2) {
arr[k] = R[j];
j++;
k++;
}
}
</script>

</head>
<body>

<table id="myTable" border="1">
<thead>
<tr>
<th onclick="sortTable(0)">Alphabetical Data</th>
<th onclick="sortTable(1)">Numerical Data</th>
<th onclick="sortTable(2)">Alphanumerical Data</th>
</tr>
</thead>
<tbody id="myTableBody">
<tr>
<td>Hello</td>
<td>132</td>
<td>CR7</td>
</tr>
<tr>
<td>Alphabet</td>
<td>798</td>
<td>LM10</td>
</tr>
<tr>
<td>Coding</td>
<td>498</td>
<td>07CL</td>
</tr>
<tr>
<td>Redefined</td>
<td>369</td>
<td>18WC</td>
</tr>
</tbody>
</table>
</body>
</html>

Sunday, 26 July 2015

Android Check Network Connection

You may be building an application which requires an Internet connection. It is very important to detect the internet connection before the application starts working so that to prevent the application from raising exceptions. Here I am explaining how to achieve the goal.

First you need to include the permissions in the Manifest file after the <application> tag.

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

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

After including the permissions, just add a few lines of code where you want to detect the internet connection.

ConnectivityManager cm = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo[] arrar_ni = cm.getAllNetworkInfo();

for (NetworkInfo ni : arrar_ni)

{

if (ni.getTypeName().equalsIgnoreCase("WIFI"))

{

if (ni.isConnected())

{

Toast.makeText(this, "WiFi Available", Toast.LENGTH_LONG).show();

} else

{

Toast.makeText(this, "WiFi Not Available", Toast.LENGTH_LONG).show();

}

if (ni.getTypeName().equalsIgnoreCase("MOBILE"))

{

if (ni.isConnected())

{

Toast.makeText(this, "Mobile Available", Toast.LENGTH_LONG).show();

} else

{

Toast.makeText(this, "Mobile Not Available", Toast.LENGTH_LONG).show();

}

The above code will generate Toast displaying the availability and type of internet connection. You can replace the Toast statements with your code according to the requirement of your application.