Java Projects

Projects and Practical Applications

Learn how to apply your Java knowledge to real-world projects.

In this section, we will build small applications using the features you've learned throughout the tutorial.

Why Build Projects?

Projects are an essential part of learning Java. Start small and gradually add more features:

• Understand how real programs are structured
• Practice combining concepts (e.g., methods, loops, file handling)
• Improve your debugging and problem-solving skills
• Prepare for job interviews and relevant exercises

Project Examples

You can start with very small projects that use simple input and output. For example, write a program that:

• Asks for your name
• Asks for your age
• Prints: Hi <name>! You will turn <age+1> next year.

Once you are comfortable, try slightly bigger projects that combine loops, conditions, and arrays:

• Create a small shopping list program (store items and print them)
• Guess a Number Game
• Calculate a Student's Average

As your skills grow, move on to more advanced projects that use methods, classes, and file handling:

• Simple Calculator
• Address Book
• To-Do List
• Quiz Game

Project: Calculate a Student's Average

Let's create a program to calculate a student's average from multiple grades.

The program asks the user to enter 1 to 5 grades and calculates the average. Then it displays the average and a corresponding letter grade (A to F):

import java.util.Scanner;

public class Main {

  // Returns a letter grade based on the average
  static char gradeFunction(double avg) {
    if (avg >= 90) return 'A';
    else if (avg >= 80) return 'B';
    else if (avg >= 70) return 'C';
    else if (avg >= 60) return 'D';
    else return 'F';
  }

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

    System.out.print("How many grades (1 to 5)? ");
    int count = scanner.nextInt();

    // Validate the input count
    if (count < 1 || count > 5) {
      System.out.println("Invalid number. You must enter between 1 and 5 grades.");
      scanner.close();
      return; // Exit
    }

    double sum = 0.0;

    // Read each grade
    for (int i = 1; i <= count; i++) {
      System.out.print("Enter grade " + i + ": ");
      double grade = scanner.nextDouble();
      sum += grade;
    }

    double avg = sum / count;

    System.out.println("Average: " + avg);
    System.out.println("Letter grade: " + gradeFunction(avg));

    scanner.close();
  }
}

Key Concepts Used: loops, methods, conditions, input handling with Scanner, and basic logic.

Practice Challenge

Build your own small project. For example, write a program that:

• Asks the user to enter up to 5 items they need to buy
• Stores the items in an array
• Prints the full shopping list
• Counts how many items were entered

Extra Challenge: Add a feature that lets the user search for an item and tells them if it is in the list.

Open your favorite Java IDE (for example IntelliJ IDEA or VS Code) and experiment on your own!