Lab Assignment Report - Student Grades (Hash Map)

Introduction

In this lab assignment, we are tasked with working on a Java program that involves a HashMap containing student names as keys and their corresponding grades as values.

The objective is to read in the name of a student, output their original grade, and then read in and output their new grade. The user will be prompted to enter the student's name and grade, which can be separated by either a space or a new line.

Methodology

The assignment involves several steps:

1. Initialize a HashMap named "studentGrades" with pre-entered student names as keys and their corresponding grades as values.
2. Prompt the user to enter a student's name and grade.
3. Retrieve and output the original grade of the student from the HashMap.
4. Update the student's grade in the HashMap with the new grade provided by the user.
5. Output the new grade of the student.

Code Implementation

Below is the Java code for implementing the aforementioned steps:

import java.util.Scanner;
import java.util.HashMap;

public class Lab7 {
public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    String studentName;
    double studentGrade;

    HashMap<String, Double> studentGrades = new HashMap<>();

    // Pre-entered student grades
    studentGrades.put("Harry Rawlins", 84.3);
    studentGrades.put("Stephanie Kong", 91.0);
    studentGrades.put("Shallen Tennyson", 78.6);
    studentGrades.put("Quincy Wraight", 65.4);
    studentGrades.put("Janine Antinori", 98.2);

    // Prompt the user to enter a student's name
    System.out.print("Enter a student's name: ");
    studentName = scanner.nextLine();

    // Retrieve and output the original grade
    if (studentGrades.containsKey(studentName)) {
        double originalGrade = studentGrades.get(studentName);
        System.out.println(studentName + "'s original grade: " + originalGrade);

        // Prompt the user to enter the new grade
        System.out.print("Enter the new grade: ");
        studentGrade = scanner.nextDouble();

        // Update the student's grade in the HashMap
        studentGrades.put(studentName, studentGrade);

        // Output the new grade
        System.out.println(studentName + "'s new grade: " + studentGrade);
    } else {
        System.out.println("Student not found in the database.");
    }
}
}

Results

When you run the provided Java program, it will prompt the user to enter a student's name. If the student is found in the HashMap, it will display their original grade. Then, the user will be prompted to enter a new grade for the student. After entering the new grade, the program will update the student's grade in the HashMap and display the new grade. If the student is not found in the database, a message indicating that the student was not found will be displayed.

Conclusion

This lab assignment has provided hands-on experience in working with HashMaps in Java. It demonstrates how to store and retrieve data efficiently using key-value pairs. By allowing the user to input and update student grades, the program showcases the flexibility and usefulness of data structures like HashMaps in real-world applications.

Appendix

Below is the Java class used in this assignment:

Lab7.java

import java.util.Scanner;
import java.util.HashMap;

public class Lab7 {
public static void main(String[] args) {
    // ... (Refer to the Methodology section for the complete code)
}
}