To put your understanding of **Java program structure** and **printing output** into practice, write a simple Java program that displays a custom message. Your task is to create a file named `Main.java` with a `Main` class, following the structure you have learned. Inside the `main` method, use the `System.out.println` statement to print the message **Welcome to Java Programming!** to the console. Make sure you include the correct package declaration and class structure as demonstrated in earlier chapters.

package com.example;

import static org.junit.jupiter.api.Assertions.assertTrue;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.regex.Pattern;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

public class MainTest {

    @Test
    @DisplayName("main() prints Welcome to Java Programming! (case-insensitive, flexible whitespace)")
    void testPrintsWelcomeMessageFlexible() {
        ByteArrayOutputStream outContent = new ByteArrayOutputStream();
        PrintStream originalOut = System.out;
        System.setOut(new PrintStream(outContent));

        Main.main(new String[]{});

        System.setOut(originalOut);

        String output = outContent.toString().trim();
        Pattern pattern = Pattern.compile("welcome\\\s+to\\\s+java\\\s+programming!?", Pattern.CASE_INSENSITIVE);
        assertTrue(pattern.matcher(output).find(), "Actual output: " + output);
    }
}

MainTest.java

A beginner-friendly course introducing the essentials of Java programming, including syntax, data types, control flow, and foundational object-oriented concepts. Each section builds on the previous, with practical challenges to reinforce learning.

Learn the basics of Java syntax, structure, and how to write your first program.

Dive into Java's primitive data types and learn how to declare and use variables.

Master the basics of decision making and repetition in Java programs.

Discover how to write reusable code using methods in Java.

Get started with object-oriented programming by defining and using simple classes.

Challenge: Hello Java

Ratkaisu