Use cases in Java - Practice Problems & Coding Challenges

trophy

Challenge - 5 Problems

💻 code output

intermediate

Output of method call with record use case

What is the output of the following Java code using records to represent a use case?

Java

record User(String name, int age) {}

public class Main {
    public static void main(String[] args) {
        User user = new User("Alice", 30);
        System.out.println(user.name() + " is " + user.age() + " years old.");
    }
}

A Alice is 30 years old.

B User[name=Alice, age=30]

C Alice 30

D Compilation error

🧠 conceptual

intermediate

Purpose of use cases in software development

Which of the following best describes the main purpose of use cases in software development?

A To define detailed database schemas for the application

B To write unit tests for each method in the code

C To specify the hardware requirements for deployment

D To describe interactions between users and the system to achieve goals

🔧 debug

advanced

Identify the error in this use case implementation

What error will this Java code produce when run?

Java

public class UseCase {
    private String action;
    public UseCase(String action) {
        this.action = action;
    }
    public void execute() {
        System.out.println("Executing " + action);
    }
    public static void main(String[] args) {
        UseCase uc = null;
        uc.execute();
    }
}

A Compilation error: cannot find symbol execute

B NullPointerException at runtime

C No output, program ends silently

D IllegalStateException at runtime

📝 syntax

advanced

Correct syntax for defining a use case class with a method

Which option shows the correct syntax to define a Java class named UseCase with a method run that prints "Running use case"?

A

public class UseCase {
    public void run() {
        System.out.println("Running use case");
    }
}

B

public UseCase {
    void run() {
        System.out.println("Running use case");
    }
}

C

public class UseCase {
    void run() {
        System.out.println("Running use case");
    }
}

D

public class UseCase {
    public run() {
        System.out.println("Running use case");
    }
}

🚀 application

expert

Number of use case objects created and their output

Consider this Java code creating use case objects. How many objects are created and what is printed?

Java

public class UseCase {
    private final String name;
    public UseCase(String name) {
        this.name = name;
    }
    public void execute() {
        System.out.println("Use case: " + name);
    }
    public static void main(String[] args) {
        UseCase[] cases = new UseCase[3];
        for (int i = 0; i < cases.length; i++) {
            cases[i] = new UseCase("Case" + (i + 1));
        }
        for (UseCase uc : cases) {
            uc.execute();
        }
    }
}

A 1 object created; prints Use case: Case3

B 3 objects created; prints Use case: Case3 three times

C 3 objects created; prints Use case: Case1\nUse case: Case2\nUse case: Case3

D Compilation error due to array initialization