Week 3: Java – Classes and Methods

---

Q1. Student Average Score

Objective: Create a class Student with a method to input student details and calculate the average of three exam scores.

import java.util.Scanner;

class Student {
    static void Details() {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = sc.nextLine();

        System.out.print("Enter score for exam 1: ");
        float e1 = sc.nextFloat();

        System.out.print("Enter score for exam 2: ");
        float e2 = sc.nextFloat();

        System.out.print("Enter score for exam 3: ");
        float e3 = sc.nextFloat();

        float finalMean = (e1 + e2 + e3) / 3;

        System.out.println("Student: " + name);
        System.out.println("Average score: " + finalMean);

        sc.close();
    }
}

public class q1 {
    public static void main(String[] args) {
        Student.Details();
    }
}

Key Points:

• static method can be called without creating an object.
• Scanner is used for input.
• Average calculation: (e1 + e2 + e3) / 3.
• Prints both student name and average.

---

Q2. Bank Account Operations

Objective: Simulate a simple bank account with deposit and withdrawal operations using a class.

import java.util.Scanner;

class BankAccount {
    private String accountNumber;
    private double balance;

    public static void details() {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your account number: ");
        String accountNumber = sc.nextLine();

        double balance = 0.0;
        System.out.println("Account created with balance $0.00");

        // Deposit
        System.out.print("Enter deposit amount: ");
        double deposit = sc.nextDouble();
        balance += deposit;
        System.out.println("Deposit Successful.");
        System.out.println("Account: " + accountNumber + ", Balance: " + balance);

        // First Withdrawal
        System.out.print("Enter withdrawal amount: ");
        double withdraw = sc.nextDouble();
        if (withdraw <= balance) {
            System.out.println("Withdrawal Successful.");
            balance -= withdraw;
        } else {
            System.out.println("Insufficient balance.");
        }
        System.out.println("Account: " + accountNumber + ", Balance: " + balance);

        // Second Withdrawal
        System.out.print("Enter withdrawal amount: ");
        withdraw = sc.nextDouble();
        if (withdraw <= balance) {
            System.out.println("Withdrawal Successful.");
            balance -= withdraw;
        } else {
            System.out.println("Insufficient balance.");
        }
        System.out.println("Account: " + accountNumber + ", Balance: " + balance);

        sc.close();
    }
}

public class q2 {
    public static void main(String[] args) {
        BankAccount.details();
    }
}

Key Points:

• private variables (accountNumber and balance) encapsulate data.
• Deposit and withdrawal operations update the balance.
• Simple error checking: cannot withdraw more than balance.
• Uses static method to demonstrate class-level method access.

---

Week 3 Notes:

1. static methods allow calling without creating an object.
2. Scanner inputs for different data types (String, int, float, double).
3. if-else is used for validation (like checking withdrawal amount).
4. Encapsulation: Use private for sensitive data, can use methods for operations.

---

Comments