Use cases in Java - Step-by-Step Execution

flowchart

Concept Flow - Use cases

Identify Actor

↓

Define Goal

↓

Describe Steps

↓

Handle Exceptions

↓

Review & Refine

↓

Use Case Complete

Use cases show how a user (actor) interacts with a system to reach a goal, step by step.

code_blocks

Execution Sample

Java

public class UseCaseExample {
    public static void main(String[] args) {
        System.out.println("User logs in successfully.");
    }
}

This simple Java program prints a message simulating a use case where a user logs in.

data_table

Execution Table

Step	Action	Description	Output
1	Start main method	Program starts running main method
2	Execute println	Print message to console	User logs in successfully.
3	End main method	Program finishes execution

💡 Program ends after printing the message.

search_insights

Variable Tracker

Variable	Start	After Step 2	Final
args	String[] (empty or input)	Unchanged	Unchanged

key

Key Moments - 2 Insights

▶What does the println statement represent in a use case?

▶Why is there no variable change in this simple use case?

psychology

Visual Quiz - 3 Questions

Look at the execution table, what is printed at step 2?

A Program finishes execution

B Program starts running main method

C User logs in successfully.

D No output

photo_camera

Concept Snapshot

Use cases describe how users interact with a system.
They show actors, goals, and step-by-step actions.
In Java, use cases can be represented by code simulating user actions.
Output often shows system response to user input.
Use cases help understand system behavior from user view.

contract

Full Transcript

Use cases are stories about how a user interacts with a system to achieve a goal. We start by identifying the user (actor), then define what they want to do (goal). Next, we describe the steps the user and system take. We also consider what can go wrong and fix it. Finally, we review the use case to make sure it is clear. In Java, a simple use case can be shown by a program that prints a message, like a user logging in. The execution table shows each step: starting the program, printing the message, and ending the program. Variables may or may not change depending on the program. Understanding these steps helps beginners see how use cases relate to code and system behavior.