Expression Evaluating - Using Java Stack

import java.util.List;
import java.util.Stack;

public class EvaluatingExpression {

  public static void main(String[] args) {
    System.out.println(evaluateExp("2+2"));
    System.out.println(evaluateExp("2 * ( 4 * 5 + 1 )"));
  }

  public static int evaluateExp(String expression) {
    char[] tokens = expression.toCharArray();
    Stack<Integer> values = new Stack<Integer>();
    Stack<Character> operators = new Stack<Character>();
    for (int i = 0; i < tokens.length; i++) {
      if (tokens[i] == ' ') {
        continue;
      }
      if (tokens[i] >= '0' && tokens[i] <= '9') {
        StringBuilder sb = new StringBuilder();
        while (i < tokens.length && tokens[i] >= '0' && tokens[i] <= '9') {
          sb.append(tokens[i++]);
        }
        i--;
        values.push(Integer.parseInt(sb.toString()));
      } else if (tokens[i] == '(') {
        operators.push(tokens[i]);
      } else if (tokens[i] == ')') {
        while (operators.peek() != '(') {
          values.push(applyOperation(operators.pop(), values.pop(), values.pop()));
        }
        operators.pop();
      } else if (isOperator(tokens[i])) {
        while (!operators.isEmpty() && hasPrecedence(tokens[i], operators.peek())) {
          values.push(applyOperation(operators.pop(), values.pop(), values.pop()));
        }
        operators.push(tokens[i]);
      }
    }
    while (!operators.isEmpty()) {
      values.push(applyOperation(operators.pop(), values.pop(), values.pop()));
    }
    return values.pop();

  }

  private static boolean hasPrecedence(char op1, char op2) {
    if (op2 == '(' || op1 == ')') {
      return false;
    }
    if ((op1 == '*' || op1 == '/') && (op2 == '+' || op2 == '-')) {
      return false;
    }
    return true;
  }

  private static boolean isOperator(char ch) {
    return List.of('+', '*', '-', '/').contains(ch);
  }

  private static Integer applyOperation(Character ope, Integer a, Integer b) {
    return switch (ope) {
      case '+' -> a + b;
      case '-' -> a - b;
      case '*' -> a * b;
      case '/' -> {
        if (b == 0) throw new IllegalArgumentException("Unsupported exception");
        yield a / b;
      }
      default -> throw new IllegalArgumentException("Unknown operator");
    };
  }
}

Java #6

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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)