Java Language for Selenium

Why Java for Selenium?

• Selenium written in Java, it doesn't mean that Java only more compatible with selenium, we can use other supported languages also.
• Good support for Selenium with Java, You can get more help documents and implementations from Internet.
• Majority of Selenium Testers (nearly 77%) using Java, so knowledge sharing is very easy.
• Java is platform independent language; we can use it on any Operating environment.

How much Java is required for Selenium?

• Fore Test Automation using Selenium Core Java knowledge is sufficient, Advanced Java not required.
• Java Basics and Object Oriented Concepts are required.

We can segregate Java for Selenium into 2 categories.

A) Java Basics

B) Java Object Oriented Programming

1) Overview on Java

  Java Programming Language was developed by Sun Microsystems in 1995, now it is subsidiary of Oracle Corporation.

  Java is an Object Oriented programming Language, In Java, everything is an Object. Java can be easily extended since it is based on the Object model.

  Java is a Platform independent Language. It can be compiled and interpreted.

  Java is Simple, It is easy to learn and implement.

  Java is Securable, using Java we can develop virus free and tamper free systems.

2) Java Environment Setup

  We have to setup java environment to write and execute Java programs, It

  Varies from one operating system to another.

  If it is DOS (from Command prompt in Windows), install java Software (JDK) and set Environment variables.

  If it is Windows GUI, install Java and Eclipse(Java Editor) to write and execute Java programs

3) Java Syntax

  Java is case sensitive language(deference is there in between upper and lower case letters)

  Ex: Identifiers UFT and uft have different meaning in java

  First letter of a Class Name should be in upper case.

  Method names should start with lower case letter

  Java Program file name should exactly match with class name.

  public static void main (String args[])- Java program execution starts from main method, which is mandatory in every java program.

  Every statement should end with semi colon symbol.

4) Usage of Java 

  Developing Desktop Applications (Ex: Acrobat Reader)

  Developing Web Applications

  Developing Enterprise Applications (ex: banking, Insurance Applications)

  developing mobile applications

  Embedded systems

  smart cards

  Games etc...

A) java Basics

1) Comments in Java

Purpose of comments

·         To make the code readable

·         To make the Disable from execution

Java supports Single line comment and multiple lines comment.

2) Data Types in Java

There are two categories of Data types in Java

a) Primitive data types

b) Reference data types

3) Variables

a) Local variables

b) Instance variables

c) Class / Static variables

4) Java Modifiers

Modifiers are used to set access levels for Classes, variables, methods

etc...

a) Access Modifiers (Default, Public, Private, Protected)

b) Non-access Modifiers (Static, Final, Abstract, Synchronized)

5) Operators in java

Operators are used to perform mathematical, comparison and logical

operations.

Categories of operators:

a) Arithmetic

b) Relational operators

c) Bitwise operators

d) Logical operators

e) Assignment operators

f) Mise Operators

6) Conditional statements

Used to insert verification points and for error handling.

Types of conditional statements in Java:

a) If Statement

b) Switch statement

Types of Condition:

a) Single condition

b) Compound conditions

c) Nested conditions

Usage of conditional statements:

a) Executing a block of statements when condition is true.

b) Execute a block of statements when condition is true otherwise

execute another block of statements.

c) Decide among several alternates (Else if)

d) Executing a block of statements when more than one condition is

true.(Nested if)

e) Decide among several alternates (Switch statement)

7) Loop statements

used for repetitive execution.

Types of Loop Statements

a) For Loop

b) While Loop

c) Do...While Loop

d) Enhanced For Loop (mainly used for Arrays)

8) Arrays in Java

Generally, Array is a collection of similar type of elements.

In Java, Array is an object that contains elements of similar data types.

Java Array is index based, index starts from zero.

The length of an Array is established when the Array is created and

Array length is fixed.

Each item in an Array is called an Element.

Declaration of Arrays

Assigning values to elements

Advantages and Disadvantages of Arrays.

9) Java Methods

Methods are also known as procedures or functions

A Java method is a collection of statements that are grouped together to

perform an operation.

Ex: System.out.println

If you call the method, the system actually executes several statements,

in order to display a message on the console.

We can create methods with or without returning any value.

Basically Methods are two types

a) Built-in or pre-defined

    Number Methods

    Character methods

    String methods

    Date & Time Methods

    Etc...

b) User defined

    Method with returning value

    Method without returning any value

10) Regular Expressions

It is a formula for matching patterns, A Regular expression defines

search pattern for strings.

Java provides the java.util.regex package for pattern matching with

regular expressions.

11) File and I/O operations in Java.

The java.io package contains classes to perform input and output (I/O)

operations in Java.

Reading using input devices

Displaying on the console

Reading and writing text files

Working with Excel files.

12) Exception handling in Java

In Computer programming, Exception is an abnormal condition.

An exception is an event that occurs during the execution of a program

that disrupts the normal flow of instructions.

The exception handling in java is one of the powerful mechanisms to

handle the runtime errors so that normal flow of the application can be

maintained.

Java object oriented Programming

1) Class, Object, Method

In object oriented programming system(OOPS), we design a program using

Objects and classes.

Object:

It is an entity that has states and behaviors is known as Object.

Ex: Pen, Chair, Table, Computer etc...

States / Properties of Dog object are color, height, weight etc... and

behaviors moving, barking, jumping etc...

Class:

Class is a template or blueprint from with objects are created.

A Class a group of objects that has common properties.

Method: An operation on Object.

2) Inheritance

Inheritance is a mechanism in which one object acquires all the

properties and behaviors of parent object.

Using Inheritance we can create classes that are built upon existing

classes.

When we Inherit from an existing class, we can reuse methods and fields

from parent class and we can add new methods and fields also.

Java Supports:

a) Single Inheritance

b) Multi level Inheritance

c) Hierarchical Inheritance

Note: Java doesn't support Multiple Inheritance.

3) Method Overloading and Overriding

If a class having multiple methods with same name, but different

parameters are known as method overloading.

Method overloading increases the readability of the program.

There are two ways to overload the method in Java

a) by changing number of arguments

Ex:

add (int a, int b)

add (int a, int b, int c)

b) by changing data types

Ex:

add (int a, int b)

add (char a, char b)

In Object Oriented programming overriding means to override the

functionality of an existing method.

Method overriding provides a specific implementation of a method that is

already provided by its super class (Parent class)

It is used for runtime polymorphism.

4) Polymorphism

It is a concept by which we can perform a single in different ways.

Polymorphism derived from two Greek word poly and morphs

Poly means -many

morphs means -forms / ways, so polymorphism means many forms.

we have two types of Polymorphism in java

a) Compile time polymorphism

b) Runtime polymorphism.

We can perform polymorphism in java by method overloading and method

overriding.

5) Abstraction

Abstraction is a process of hiding the implementation details and

showing functionality to the user.

Another way, it shows important things to the user and hides internal

details.

Ex: Sending email

you just type the email and send, you don't internal process of the

email delivery.

Abstraction focuses on what the object does instead of how it does.

In two ways we can achieve Abstraction

a) Abstract Class (0 to 100%)

b) Interface (100%)

6) Encapsulation

Encapsulation is one of the four fundamental oops concepts, other three

are Inheritance, Polymorphism and Abstraction.

Encapsulation is a process of wrapping code and data together into a

single unit.

Ex: Capsule (mixed of several medicines)

It provides the control over the data, suppose we want to value of the

id greater than 100 only, we can write the logic inside the setter method.

7) Java packages

A Java package is a group of similar type of classes, interfaces and

sub-packages.

There are two types of java packages

a) Built in packages

Ex: io, util, sql etc...

b) User defined packages

8) Interfaces in Java

An interface is a collection of abstract methods.

An interface is not a class, writing an interface is similar to writing

a class, but two are different concepts.