Java #6

Java #5

Java #4

Java #3

Java #2

Java #1

Interview Questions - Java

1. What is OOP?

   Object Oriented Programming is programming paradigm, that works on the following principals:

   • Abstraction
   • Inheritance
   • Polymorphism
   • Encapsulation

2. What is Abstraction?

   Abstraction is the process of hiding certain details and showing only essential information to the user.

3. What is Polymorphism?

   Polymorphism is a concept by which we can perform a single action in different ways. ... So polymorphism means many forms.

4. What is Inheritance?

   Inheritance is a mechanism in which one object acquires all the properties and behaviors of a parent object.

5. What is immutable Object and how to create a immutable class?

1. What is JDK,JRE JVM?

2. Difference between prasing and type casting?

3. What is constructor? difference between constructor and method?

4. What are access specifiers in java ?

5. Write a program to check given string is Anagram or not?

1. What is Functional interface?

2. Abstract class Vs Interface

3. Overloading Vs Overriding

4. What is marker interface?

5. Write a program to delete duplicate elements from the array and display then ascending order

1. ArrayList Vs LinkedList

2. HashMap Vs HashTable

3. HashMap vs ConcurrentHashMap

4. How HashMap works internally?

5. Write a program to implement custom hashmap

1. Callable Vs Runnable

2. Synchronized block vs method

3. What are the different ways to create thered in java?

4. How to run multiple threads simltaniously

5. Write a program to create singleton class

1. What is design patterns?

2. finally Vs finalize

3. What are the SOLID principals?

4. What is the default capacity of LinkedList, HashMap ?

5. Write a program for builder and factory patterns

1. What is Streams?

2. Inner classes Vs Lambdas

3. What is difference between stream vs parallel stream?

4. Future vs CompletableFuture

5. Write a program to convert list of string to map where key is string and length of the string is value using streams

1. Where do you volatile keyword?

2. volatile vs transient

3. How to store custom object as key in HashMap?

4. What is exception? What are different ways to create custom exception

5. Write a program to create custom exception class?

1. What is serialaization?

2. What is serial version id?

3. this Vs Super in java?

4. What are different ways to create object?

5. Write a program to create custom annotation?

1. How garbage collectors work in JVM?

2. What is major GC and minor GC?

3. What is class loader?

4. How to increase memeory size while running java applicaation?

5. Write a program to get max paid employee of the organization using java stream?

Bootstrp + jQuery + news REST API example

Sample code snippet will help in understanding how to consume REST services using jQuery and displaying content using Bootstrap.

The directory structure:

Live : https://jsl-news.glitch.me/

newspp
   - css
         - main.css
  - js
       - news.js

  - index.html

main.css

 #subBtn{  
   margin-top: 13%;  
 }  

index.html

 <!doctype html>  
 <html lang="en">  
  <head>  
   <!-- Required meta tags -->  
   <meta charset="utf-8">  
   <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">  
   <!-- Bootstrap CSS -->  
   <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">  
   <link rel="stylesheet" href="css/main.css">  
   <title>News - Items</title>  
  </head>  
  <body>  
   <div class="py-3 bg-primary text-white text-center">  
     <h3>Search worldwide news with code</h3>  
     <p class="lead">Get breaking news headlines, and search for articles from over 30,000 news sources and blogs with our news API</p>  
   </div>  
   <div class="container">  
     <h5 class="text-muted text-center mt-2">Please select the details to get updated news</h5>  
     <div class="row">  
       <div class="col-md-3"></div>  
       <div class="col-md-3">  
         <label for="country">Select Country</label>  
         <select class="form-control" id="country">  
           <option value="in">India</option>  
           <option value="us">United State</option>  
           <option value="sg">Singapore</option>  
         </select>  
       </div>  
       <div class="col-md-3">  
         <label for="category">Select Category</label>  
         <select class="form-control" id="category">  
           <option value="sports">Sports</option>  
           <option value="health">Health</option>  
           <option value="business">Business</option>  
         </select>  
       </div>  
       <div class="col-md-3">  
         <button id="subBtn" class="btn btn-primary">Submit</button>  
       </div>  
     </div>  
     <!--New items-->  
     <div class="row mt-5">  
       <div class="col-md-6 offset-md-3" id="showResult">  
       </div>  
     </div>  
    </div>  
   <!-- Optional JavaScript -->  
   <!-- jQuery first, then Popper.js, then Bootstrap JS -->  
   <script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>  
   <script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>  
   <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>  
   <script src="js/news.js"></script>  
 </body>  
 </html>  

JavaScript: news.js

  const url = "https://newsapi.org/v2/top-headlines?";  
  const apikey = "5c636a468a90465aa7cab199265d7299";  // Change the key by registering with news api
 class News{  
   constructor(title,author,description,urlToImage){  
     this.title = title;  
     this.author = author;  
     this.description = description;  
     this.urlToImage = urlToImage;  
   }  
 }  
  subBtn = document.querySelector("#subBtn");  
 function showNews(news){  
   str ="";  
   count = 1;  
   for(let item of news){  
     str += `<b>#${count++}<br>  
     <div class="card mt-2 mb-2">  
     <img src="${item.urlToImage}" class="card-img-top" alt="...">  
     <div class="card-body">  
      <h5 class="card-title">${item.title}</h5>  
      <p class="card-text">  
      <b>${item.author}</b>  
      <br>  
      ${item.description}  
      </p>  
      <a href="#" class="btn btn-primary">Go somewhere</a>  
     </div>  
    </div>  
    `  
   }  
   document.querySelector("#showResult").innerHTML = str;  
 }  
 subBtn.addEventListener('click',(e)=>{  
     let countryName = document.querySelector("#country").value;  
     let categoryValue = document.querySelector("#category").value;  
     let reqURL = `${url}country=${countryName}&apiKey=${apikey}&category=${categoryValue}`;  
     fetch(reqURL).then(rawData=>{  
       return rawData.json();  
     }).then(data=>{  
       news = [];  
       articles = data["articles"];  
          for(let article of articles){  
         newsItem = new News(article.title,article.author,article.description,article.urlToImage);  
         news.push(newsItem);  
       }  
       showNews(news);  
     }).catch(error=>{  
       alert("While getting news we got ",error);  
     })  
  })  

 Sample output:

UI assignment Questions

Assingment Questions - UI

1. HTML and CSS

Python Programming Questions

1. Count the occurrence of the letter in the given string?

name = "ThulasiDhasan"
map = {}
for ch in name:
  map[ch] = map.get(ch, 0) + 1
print(map)

2. Flatten list of the list in Python

lst = [[2, 3, 5], [6, 7, 8], [9, 0, 1]]
t_lst = [ele for sublist in lst for ele in sublist]
print(t_lst)

Python project - Contactbook

Contact Book: Sample application to perform CRUD operations using Python, MySQL.

             MySQL
             Python 3.x

Libraries used :
           pymsql , beatutifultable

Installation of Libraries using pip
           pip install pymsql
           pip install beautifultable

This application performs basic CRUD orations to demonstrate Python end-to-end application.

Note: Update and delete methods were not called from main, you can give a try...

contact.py

from collections import namedtuple

Contact = namedtuple("Contact", ["cid","name", "email", "mobile"])

config.py

mysql = {
    'host': 'localhost',
    'user': 'root',
    'passwd': 'password',
    'db': 'counselor_db'}

util.py

import pymysql
import config

class DbUtil:

    @staticmethod
    def get_connection():
        try:
            con = pymysql.connect(config.mysql['host'], config.mysql['user'],config.mysql['passwd'],config.mysql['db'])
        except pymysql.MySQLError as error:
            print('Exception number: {}, value {s}'.format(error.args[0], error))
            raise
        else:
            return con

    @staticmethod
    def close_connection(conn):
        try:
            conn.close()
        except pymysql.MySQLError as error:
            print("While closing connection ...")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
            raise

    @staticmethod
    def close_cursor(cursor):
        try:
            cursor.close()
        except pymysql.MySQLError as error:
            print("While closing the cursor ...")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
            raise

dboperations.py

import config
from util import DbUtil
import pymysql
from contact import Contact


class ContactDbOperations:

    def add_contact(self, new_contact):
        try:
            connection = DbUtil.get_connection()
            with connection.cursor() as cursor:
                cursor.execute("insert into contact(name,email,mobile) values(%s,%s,%s)", (new_contact.name
                                                                        , new_contact.email
                                                                                            , new_contact.mobile))
            connection.commit()

        except pymysql.MySQLError as error:
            print("While inserting Data ...")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            DbUtil.close_connection(connection)
            DbUtil.close_cursor(cursor)

    def get_contact(self, cid):
        try:

            conn = DbUtil.get_connection()
            cursor = conn.cursor()
            cursor.execute("select  cid, name, email, mobile from contact where cid = %s", cid)
            contact = Contact(*cursor.fetchone())
            return  contact
        except pymysql.DatabaseError as error:
            print("While getting data from DB using id... ")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            DbUtil.close_connection(conn)
            DbUtil.close_cursor(cursor)

    def update_contact(self, contact):
        try:
            conn = DbUtil.get_connection()
            cursor = conn.cursor()
            cursor.execute("update contact set name = %s ,email = %s, mobile = %s where cid = %s", contact)
            conn.commit()

        except pymysql.DatabaseError as error:
            print("While updating ... ")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            DbUtil.close_connection(conn)
            DbUtil.close_cursor(cursor)

    def get_all_contacts(self):
        try:
            connection = DbUtil.get_connection()
            with connection.cursor() as cursor:
                cursor.execute("select cid, name, email, mobile from contact")
                rows = cursor.fetchall()
                contacts = self.get_list_data(rows)
                return contacts
        except Exception as error:
            print("While retrieving data ... ")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            if connection:
                DbUtil.close_connection(connection)
                DbUtil.close_cursor(cursor)

    def search_contact(self, search_str):
        try:
            connection = DbUtil.get_connection()
            with connection.cursor() as cursor:
                cursor.execute("select cid, name, email, mobile from contact where name like %s ", ('%' + search_str + '%'))
                rows = cursor.fetchall()
                contacts = self.get_list_data(rows)
                return contacts
        except Exception as error:
            print("While searching Data ...")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            DbUtil.close_connection(connection)
            DbUtil.close_cursor(cursor)

    @staticmethod
    def delete_contact(cid):
        try:
            connection = DbUtil.get_connection()
            cursor = connection.cursor()
            cursor.execute("delete from contact where cid = %s ", cid)
            connection.commit()

        except pymysql.DatabaseError as error:
            print("While deleting data ...")
            print('Exception number: {}, value {!r}'.format(error.args[0], error))
        finally:
            DbUtil.close_connection(connection)
            DbUtil.close_cursor(cursor)

    @staticmethod
    def get_list_data(rows):
        return [Contact(*row) for row in rows]

contactservice.py

from dboperations import ContactDbOperations
from contact import Contact
from beautifultable import BeautifulTable

class ContactService:

    def __init__(self):
        self.cs = ContactDbOperations()

    def add_contact(self):
        name = input("Name : ")
        email = input("Email : ")
        mobile = input("Mobile : ")
        contact = Contact(0, name, email, mobile)
        self.cs.add_contact(contact)
        self.show_all_contacts()

    def show_all_contacts(self):
        contacts = self.cs.get_all_contacts()
        ContactService.paint_data_list(contacts)

    def search_contact(self):
        name = input("Enter search name :")
        contacts = self.cs.search_contact(name)
        if contacts:
            ContactService.paint_data_list(contacts)
        else:
            print("No data found with search name :{}".format(name))

    @staticmethod
    def paint_data(data):
        table = BeautifulTable()
        table.column_headers = ["CID", "NAME", "EMAIL", "MOBILE"]
        table.append_row([data.cid, data.name, data.email, data.mobile])
        print(table)

    @staticmethod
    def paint_data_list(data):
        table = BeautifulTable()
        table.column_headers = ["CID", "NAME", "EMAIL", "MOBILE"]
        for li in data:
            table.append_row([li.cid, li.name, li.email, li.mobile])
        print(table)

main.py

if __name__ == '__main__':
    cs = ContactService()
    while True:
        print("*"*40)
        print("1. Add Contact 2. View All 3.Search 4. Exit")
        print("*"*40)
        choice = int(input("Enter your choice :"))
        if choice == 1:
            cs.add_contact()
        elif choice == 2:
            cs.show_all_contacts()
        elif choice == 3:
            cs.search_contact()
        elif choice == 4:
            exit()
        else:
            print("Enter only 1 to 4 ......")