Spring Boot Hello World Example

Spring Boot is a Java-based framework. This spring boot application example project uses Spring Tool Suite to demonstrate a hello world example ( STS IDE ). This spring boot starter project example is described in detail. Finally, in this tutorial, we will see how to use Spring Tool Suite to run the hello world example project in Spring Boot. On this page, we’ll show you how to use Spring Tool Suite to launch the Hello World application in Spring Boot. We will use JDK 8 and Maven to create this application. In this section, we will walk you through the steps of creating this application, compiling it, and running it to see the message “Hello World” in the console. Begin Spring Boot Project Hello World



Start Spring Boot Hello World Project

Click on the “File “menu in the top left corner-> then click on the “New “menu-> then click on the “Spring Starter Project “button in the image below.

The link above will open a wizard “New Spring Starter Project” as a pop-up window. Change the Name to “SpringHelloWorld”. By default, the location will show in the work space. If you want to change to another location, un-check the “Use default location” location and select the location you want. Change Group, Artifact, Description, Package as shown in the picture. Leave the remaining field as the default value. To move next page, click on the “Next “button.

On the following page, the “New Spring Starter Project Dependencies” window will appear. The project dependencies will be discussed in detail in subsequent articles. For the time being, leave all fields with their default values. To proceed to the next page, click the “Next” button.

It will show “Site Info” on the next page as shown below. To create a default project, click “Finish” button.



Default Spring Boot Project File Structures

Now it creates the default Spring Boot Project. The directory structures are created as shown in the image below. The file “SpringHelloWorldApplication.java” was created in the source folder. This is the main method starting file. A default configuration file called “application.properties” is created in the resource folder. A default test file with default code is created in the test folder “SpringHelloWorldApplicationTest.java”. In the root directory, a pom.xml file is created.

The file pom.xml will contain the code below. By default, spring-boot-starter and spring-boot-starter-test maven dependency is added in the pom.xml file. spring-boot-starter dependency will download all the spring framework core jar files. The framework for dependency injection ( DI ) and inversion of control ( IOC ) is added from this spring-boot-starter maven dependency.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.yawintutor</groupId>
	<artifactId>SpringHelloWorld</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>SpringHelloWorld</name>
	<description>Spring Boot Hello World Project</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

The main spring boot file “SpringHelloWorldApplication.java” is displayed as below. It contains a main method by default. The annotation @SpringBootApplication is added in this class. This annotation informs about starting of the spring boot application. The main method is the starting point of the application. SpringApplication.run() api starts the project and the command line arguments are passed into the application.

package com.yawintutor.helloworld;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringHelloWorldApplication {

	public static void main(String[] args) {
		SpringApplication.run(SpringHelloWorldApplication.class, args);
	}

}

In the test folder, the default test java file “SpringHelloWorldApplication.java” contains the default test code. The annotation @SpringBootTest is used to inform about the unit test classes. The annotation @RunWith loads the Junit framework using the starting class SpringRunning.class.

package com.yawintutor.helloworld;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringHelloWorldApplicationTests {

	@Test
	public void contextLoads() {
	}

}


Running the default Spring Boot Application

Open the file “SpringHelloWorldApplication.java” in the Project Explorer window by double-clicking on the file name.

You can use the Spring Tool Suite to run the Spring boot application in three ways.

  • First option – Click on the “Run “menu in the menu-> Click on “Run As “-> click on “2. Spring Boot App”
  • Second option – Right click on “SpringHelloWorldApplication.java” -> Click on “Run As” -> click on “Run Spring Boot App”
  • Third option- Click in the toolbar on the “Run” button.

The output is displayed in the console window as below. By default, the default log statements are displayed in the console window.



Create Hello World Application

Open the file “SpringHelloWorldApplication.java” in the Project Explorer window by double clicking on the file name. Add the code as below. The system.out.println contains a string “Welcome to Hello World” that is printed in the spring boot console.

package com.yawintutor.helloworld;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringHelloWorldApplication {

	public static void main(String[] args) {
		SpringApplication.run(SpringHelloWorldApplication.class, args);
		System.out.println("Welcome to Hello World!");
	}

}

Run the application again, Now “Hello World” will be printed in the console window. The output console window will appear as below The console window starts with a spring banner, followed by default spring boot loading log files. In the last, the “Welcome to Hello World” message is printed in the spring boot console window.

On this page, we explained how to start with Hello World example in Spring Boot using the Spring Tool Suite.



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