Spring @Value Annotation Example

In this tutorial, we will learn how to use @Value Annotation in Spring or Spring boot applications.

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@Value Annotation Overview

Spring @Value annotation is used to assign default values to variables and method arguments.

The @Value annotation is mostly used to get value for specific property keys from the properties file.

We can read spring environment variables as well as system variables using @Value annotation.

@Value Annotation Example

In this example, we will see how to use @Value annotation to read the value for a property key, and read environment variables as well as system variables.

Add the below properties to the application.properties file:

[email protected]
mail.host=gmail.com
mail.password=password

Next, we will see how to read the values for the above property keys using @Value annotation.

Using @Value Annotation:

Create a ValueAnnotationDemo class and add the following to it:

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class ValueAnnotationDemo {

    @Value("default value")
    private String testDefaultValue;

    @Value("${java.home}")
    private String javaHome;

    @Value("${HOME}")
    private String homeDir;

    @Value("${mail.email}")
    private String email;

    @Value("${mail.host}")
    private String host;

    @Value("${mail.password}")
    private String password;

    public String getTestDefaultValue() {
        return testDefaultValue;
    }

    public String getJavaHome() {
        return javaHome;
    }

    public String getHomeDir() {
        return homeDir;
    }

    public String getEmail() {
        return email;
    }

    public String getHost() {
        return host;
    }

    public String getPassword() {
        return password;
    }
}

From the above code, Spring @Value annotation is used to assign a default value to the variable:

    @Value("default value")
    private String testDefaultValue;

Spring @Value annotation used to read the property values:

    @Value("${mail.email}")
    private String email;

    @Value("${mail.host}")
    private String host;

    @Value("${mail.password}")
    private String password;

Reading spring environment variables as well as system variables using @Value annotation:

    @Value("${java.home}")
    private String javaHome;

    @Value("${HOME}")
    private String homeDir;

Testing:

Next, let's test the usage of @Value annotation:

import net.javaguides.springboot.config.ValueAnnotationDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		var context = SpringApplication.run(SpringbootDockerDemoApplication.class, args);
		ValueAnnotationDemo valueAnnotationDemo = context.getBean(ValueAnnotationDemo.class);
		System.out.println(valueAnnotationDemo.getTestDefaultValue());
		System.out.println(valueAnnotationDemo.getHost());
		System.out.println(valueAnnotationDemo.getEmail());
		System.out.println(valueAnnotationDemo.getPassword());
		System.out.println(valueAnnotationDemo.getJavaHome());
		System.out.println(valueAnnotationDemo.getEmail());
		System.out.println(valueAnnotationDemo.getHomeDir());
	}
}

Output:

default value
gmail.com
[email protected]
password
/Users/rameshfadatare/Library/Java/JavaVirtualMachines/openjdk-17.0.2/Contents/Home
[email protected]
/Users/rameshfadatare

Related Spring and Spring Boot Annotations

• Spring Boot @Bean Annotation Example
• Spring @Qualifier Annotation Example
• Spring @Autowired Annotation with Example
• Spring @Bean Annotation with Example
• Spring @Configuration Annotation with Example
• Spring @PropertySource Annotation with Example
• Spring @Import Annotation with Example
• Spring @ImportResource Annotation Example
• Spring - @Lazy Annotation Example
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• Spring @PostConstruct and @PreDestroy Example
• Spring @Repository Annotation
• Spring @Service Annotation 
• The Spring @Controller and @RestController Annotations
• Spring Boot @Component, @Controller, @Repository and @Service
• Spring @Scope annotation with Prototype Scope Example
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• Spring Boot @PathVariable
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• Spring Boot - Creating Asynchronous Methods using @Async Annotation
• @SpringBootTest Spring Boot Example
• @SpringBootTest vs @WebMvcTest
• @DataJpaTest Spring Boot Example
• Spring @PostConstruct and @PreDestroy Example
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• Spring Boot @EnableAutoConfiguration Annotation with Example
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