December 2018 ~ Selenium Automation

Monday, December 31, 2018

String Reverse Example

public class StringReverse {
public static void main(String[] args) {
String str="selenium",reverse="";
for(int i=str.length()-1;i>=0;i--) {
reverse=reverse+str.charAt(i);
}
System.out.println(reverse);
}
}
Output: muineles

TestNG Annotations

What is TesNG and What are the annotations in the TestNG?
Ans: TestNG is testing framework to run the test cases. TestNG supports annotations like:
@BeforeSuite
@BeforeTest
@BeforeClss
@Test
@Dataprovider
@Cachelookup
@AfterClass
@AfterTest
@AfterSuite

Hashmap vs Hashtable

Difference between Hashmap and Hashtable?

HashMap is non-synchronized. Hashtable is synchronized.
HashMap allows multiple threads where as hashtable doesn't
HashMap is not thread-safe where as hashtable is.
HashMap allows one null key and any number of null values. Hashtable doesn’t allow null keys and null values.

Note: We can make the HashMap as synchronized by calling this code

Map m = Collections.synchronizedMap(hashMap) [or] can be used ConcurrentHashMap for thread safe. HashMap throws ConcurrentModificationException when if other thread try to add/modify the contents of Object

ArrayList vs LinkedList

Difference between ArrayList and LinkedList?
Similarities: Both implements List interface(linkedlist also implements deque interface), maintains insertion order and can contain duplicate elements. Both are non synchronized classes can be made synchronized explicitly by using Collections.synchronizedList method .
Differences:

ArrayList internally uses a dynamic array to store the elements. LinkedList internally uses a doubly linked list to store the elements.
Updation and Deletion(manipulation) are slow because it internally uses an array. If any element is removed from the array, all the bits are shifted in memory. Manipulation with LinkedList is faster in LinkedList because it uses a doubly linked list, so no bit shifting is required in memory.
An ArrayList class can act as a list only because it implements only List. LinkedList class can act as a list and queue both because it implements List as well as Deque interfaces
ArrayList is better for storing and accessing data. LinkedList is better for manipulating data.
LinkedList has more memory overhead than ArrayList because in ArrayList each index only holds actual object (data) but in case of LinkedList each node holds both data and address of next and previous node.

Performance:

(ArrayList gives variable performance O(n) in worst case (while removing first element) and O(1) in best case (While removing last element). LinkedList remove operation gives O(1) performance)
ArrayList search operation is pretty fast compared to the LinkedList search operation. ArrayList gives the performance of O(1) while LinkedList performance is O(n).

Arraylist vs HashMap

Difference between Arraylist and HashMap?

ArrayList implements List Interface while HashMap is an implementation of Map interface.
Memory consumption is high in HashMap compared to the ArrayList.
ArrayList maintains the insertion order while HashMap doesn't maintain any order. ArrayList stores the elements only as value and maintain internally the indexing for every element. While HashMap stores elements with key and value pair, i.e. two objects. So HashMap takes more memory comparatively.
ArrayList allows duplicate elements but HashMap doesn't allow duplicate keys (It does allow duplicate values)
In ArrayList, an element can be fetched easily by specifying the index of it. But in HashMap, the elements is fetched by its corresponding key. It means that the key must be remembered always.
In ArrayList, any number of null elements can be stored. While in HashMap, only one null key is allowed, but the values can be of any number.

ARRAYLIST	HASHMAP
The java ArrayList implements List Interface	The java HashMap is implements Map interface
ArrayList always maintain insertion order of the elements	HashMap does not maintain the insertion order
ArrayList only stores value or element	HashMap stores key and value pairs
ArrayList can contain duplicate elements	HashMap does not contain duplicate keys but contain duplicate values.
We can have any numbers of null elements in ArrayList	We can have only one null key and any number of null values in HashMap
ArrayList get() method always gives an O(1) performance	HashMap get()method can be O(1) in the best case and O(n) in the worst case

Retrieve Test Data from an Excel file with Apache POI

A Java Program to retrieve the data from an excel file?

Below is the code to read .xlsx file.
XSSFWorkbook -> to read .xlsx file (Microsoft Excel 2003 and earlier)
HSSFWorkbook -> to read .xls file (Microsoft Excel 2007 and later)

Ans: We can read data from Excel using Apache POI library.

System.out.println()

System.out.println(). Simply SOP
System: is a final class in java.lang package. This class has methods to provide access to Standard Input, Standard Output and Standard Error Output streams. Can not be instantiated.
out: is final static variable of type PrintStream declared in the System class.
println(): is a overloaded method in PrintStream class. It accepts an expression as an argument and displays it in String form to the Standard Output. It is also a reference variable of Print Stream class and access println() of same class.
Below are the overloaded methods of println in PrintStream class with different arguments.
println();

println(String x);
println(boolean x);
println(char x);
println(int x);
println(long x);
println(float x);
println(double x);
println(char x[]);
println(Object x);
Every println() method makes a call to print() and adds a newline.
Note: System class can not be instantiated as constructor is declared as private.

Java Database Connectivity(JDBC)

JDBC: is an acronym for 'Java Data Base Connectivity'. It is used for accessing the databases from Java Applications. JDBC API allows to do CRUD operations on Database.
Steps to connectivity between Java program and Database:

Loading the Driver
Create the Connections
Create a Statement
Execute the Query
Close the Connections.

Loading the Driver:

We can register the driver using Class.forName("oracle.jdbc.driver.OracleDriver");

Class.forName() load the driver's class file into memory, which automatically registers it.
In JDBC API, we have java.sql.Driver, it is only an interface and it is available in JDK.
Create the Connections:
We can establish the connection using
Connection conn=DriverManager.getConnection(String url, String user, String password);
url can be created as "jdbc:oracle:thin:@hostname:port Number:databaseName"

Create a Statement: Interface define the methods and properties that enable you to send SQL or PL/SQL commands and receive data from your database.
Statement st = con.createStatement();

Execute the Query: Reads data from a database query and returns the data in a result set. The java.sql.ResultSet interface represents the result set of a database query.
ResultSet rs=stmt.executeQuery("select query);
Close the Connections:
The close() method of Connection interface is used to close the connection.
conn.close()

Software Development Life Cycle (SDLC)

SDLC: A Framework containing the Processes, Activities, and the Tasks involved in the development, operation and maintenance of a software project (spanning the life of the system) from the definition of its requirements to the termination of its use.
(or)
The Software Development lifecycle is a systematic process for building software that ensures the quality product is built.
Below are the different phases in Software Development Life Cycle:
1. Requirements Gathering or (Initiation)
2. Analysis
3. Designing
4. Coding
5. Testing
6. Delivery & Maintenance
In every phase of SDLC, four important things have to be discussed. For every phase there will be an out put in the form of Document.

-> Responsibilities or Objectives

-> Role

-> Process (Guide lines for the roles)

-> Documentation

Requirement Gathering:

Responsibility: Collecting all the specifications or requirements from the customer.
Role: This job will be done by Business Analyst (BA) and Engagement Manager Assist BA. BA deals with requirements and EM estimates excess cost for this project.
Process: BA must follow the guide lines

Taking appointment before meeting with customer.
What to talk what not to talk must be given.
Work has to be done in consistent manner.

Documentation: While dealing with the CEO of Bank, BA must get the entire requirement, note it down and then this requirement must document. He/She must follow the pre format (Template) provided by the company. This document is known as BD/ BDD/ FRS/ BRS. (BD - Business Document, BDD - Business Design Document, FRS - Functional Requirement Specification, BRS - Business Requirement Specification)

Analysis: In this phase the requirements in BDD are analyzed. In this phase, the out come is SRS. This SRS is designed in the next phase.

Responsibility:

Analysis of Requirement: Analyse explicit requirements and implicit requirements
Feasibility Study: states whether requirement is possible or not
Tentative Planning: rough planning of the requirement
Technology Selection: Analysis system requirements. e.g: for web dev Java, for documentation MS-Word etc.,

Role: System Analyst (SA)
Process: Guidelines will be provided to analyst to follow.
Documentation: In order to develop the product, the system requirements are documented and send to design phase. This document is known as SRS (System Requirement Specifications).

Design:

Responsibility: Designing of the project. In this Design there are two levels HLD (High Level Design) and LLD (Low Level Design).
Role: HLD is done by CA (Chief Architect). LLD is done by TL (Technical Leads)
Process: Guidelines will be provided to follow.
Documentation: The document designed in this phase is called Technical Design Document (TDD)

Coding:

Responsibility: In this phase programming is the responsibility
Role: Developer
Process: Developer must follow some guide lines called Coding standards. Some Coding Standards:

Code space margin has to be left
Write comments at every program function so that readability enhanced.
Color coding etc…

Documentation: All the coding files are documented in a document called Program File or Source Code Document (SCD).

Testing: Testing goes in this phase. After testing in this phase, application is send to Delivery phase.

Responsibility: Testing of the Application
Role: Test Engineers (TE, STE)
Process:

Understanding Requirements (e.g: BRS, FRS)
Writing Test cases (either manual or Automation)
Executing Test cases
analyse the test results

Documentation: Documentation in this phase is Defect Profile.

Delivery(Deployment)&Maintenance: The objective of deployment phase is to make the developed software operational in a live environment. A deployment in the operational environment comes only after the product is fully tested and accepted by the business in the acceptance stage of the testing phase
Once the software passes through all the stages without any issues, it is to undergo a maintenance process wherein it will be maintained and upgraded from time to time to adapt to change

Marker Interface

Marker Interface:
A marker interface is an empty interface with no fields or methods. These are used to indicate some information to compilers or JVMs
Ex: Serializable, Cloneable, EventListener and Remote interfaces
A Class implements them to claim the membership in a particular set.
The String class and all the wrapper classes implement the java.io.Serializable interface by default

Selenium Interview Questions and Answers

I have attended some interviews during my career. I am sharing with you questions i was asked in the interviews. Hope these questions are helpful to the readers.

A Java Program to retrieve the data from an excel file?

Difference between Arraylist and HashMap?

Difference between ArrayList and LinkedList?

Difference between HashMap and ConcurrentHashMap?

Difference between Hashmap and Hashtable?

What is TesNG and What are the annotations in the TestNG?

Write a java program to reverse a String?

Can we declare a class static in java?

Write a SQL Query to find 2nd highest salary of an employee?

Explain public static void main(String[] args){}?

How to add dependencies in the maven without specifying the version?

How to integrate maven and Jenkins?