Week 5: Java – Arrays & OOP Applications

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Q1. Find Second Largest Element in an Array

Objective: Read n integers and find the second largest value.

import java.util.Scanner;

public class P1 {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter number of elements: ");
        int n = sc.nextInt();

        if (n < 2) {
            System.out.println("Error: Array must have at least 2 elements.");
            return;
        }

        int[] arr = new int[n];
        System.out.println("Enter " + n + " elements: ");
        for(int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int firstLargest = Integer.MIN_VALUE;
        int secondLargest = Integer.MIN_VALUE;

        for (int i = 0; i < n; i++) {
            if (arr[i] > firstLargest) {
                secondLargest = firstLargest;
                firstLargest = arr[i];
            } else if (arr[i] > secondLargest && arr[i] < firstLargest) {
                secondLargest = arr[i];
            }
        }

        System.out.println("Second largest element: " + secondLargest);
        sc.close();
    }
}

Key Points:

• Initialize firstLargest and secondLargest with Integer.MIN_VALUE.
• Loop through the array and update the largest and second largest accordingly.
• Handles arrays with fewer than 2 elements.

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Q2. Showroom Article with Maximum Loss

Objective: Create Article objects with cost and selling prices, calculate loss percentage, and find the article with the highest loss.

import java.util.Scanner;

class Article {
    String name;
    float costPrice;
    float sellingPrice;
    float lossPer;

    void calc_loss_per() {
        if (costPrice > 0) {
            lossPer = ((costPrice - sellingPrice) / costPrice) * 100;
        } else {
            lossPer = 0;
        }
    }

    void display() {
        System.out.println("Article Name: " + name);
        System.out.println("Cost Price: " + costPrice);
        System.out.println("Selling Price: " + sellingPrice);
        System.out.println("Loss Percentage: " + lossPer + "%");
    }

    static void find_high_loss(Article[] articles) {
        int index = 0;
        float maxLoss = articles[0].lossPer;

        for (int i = 1; i < articles.length; i++) {
            if (articles[i].lossPer > maxLoss) {
                maxLoss = articles[i].lossPer;
                index = i;
            }
        }

        System.out.println("\nArticle with Highest Loss Percentage:");
        articles[index].display();
    }
}

public class Showroom {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter number of articles: ");
        int n = sc.nextInt();
        sc.nextLine(); // consume newline

        Article[] articles = new Article[n];

        for (int i = 0; i < n; i++) {
            articles[i] = new Article();

            System.out.println("\nEnter details for Article " + (i + 1) + ":");
            System.out.print("Name: ");
            articles[i].name = sc.nextLine();
            System.out.print("Cost Price: ");
            articles[i].costPrice = sc.nextFloat();
            System.out.print("Selling Price: ");
            articles[i].sellingPrice = sc.nextFloat();
            sc.nextLine(); // consume newline

            articles[i].calc_loss_per();
        }

        Article.find_high_loss(articles);
        sc.close();
    }
}

Key Points:

• Use array of objects (Article[]) to store multiple articles.
• calc_loss_per() computes loss percentage for each article.
• find_high_loss() identifies and displays the article with maximum loss.
• Handles user input carefully with sc.nextLine() to avoid skipping inputs.

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Week 5 Notes:

1. Arrays can store primitive types or objects.
2. Use Integer.MIN_VALUE when searching for largest values in arrays.
3. Object arrays allow methods to operate collectively (like find_high_loss()).
4. Proper input handling is important when mixing nextLine() and nextInt()/nextFloat().

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