Reading a List from Properties File and Load with Spring Annotation @Value

Reading a List from properties file and load with spring annotation @Value

Using Spring EL:

@Value("#{'${my.list.of.strings}'.split(',')}") 
private List<String> myList;

Assuming your properties file is loaded correctly with the following:

my.list.of.strings=ABC,CDE,EFG

Reading a Map from properties file and load with spring annotation @Value

application.properties:

property.map={first:value, second:value}

then in Java code you can:

@Value("#{${property.map}}")
Map<String, String> map;

Spring @Value annotation with List and default value

@Value("${myapp.values:}#{T(java.util.Collections).emptyList()}")
private List<String> defaultToEmpty;

or

@Value("#{T(java.util.Arrays).asList('${myapp.values:}')}")
private List<String> defaultToEmpty = new ArrayList();

Springboot can't read values from properties file

Considering that you use the prefix = "product-service"

you should declare your class fields as following.

    private double first;
    private double second;
    private double third;

You should also update getters and setters.

You also have another error in your code as well

private List<ProductDTO> productList = Arrays.asList(
            new ProductDTO(1,"Tomb Raider",first),
            new ProductDTO(2,"10000 rp to lol",second),
            new ProductDTO(3,"2k valorant points",third)
    );

This field is initialized when your class is initialized. But Spring initializes your bean with a proxy. So when the class is initialized your productList will have 0 values for first, second,third.

If you wish this to work you should replace

public List<ProductDTO> findAllProducts() {
        return productList;
    }

with

public List<ProductDTO> findAllProducts() {
        return Arrays.asList(
                new ProductDTO(1,"Tomb Raider",first),
                new ProductDTO(2,"10000 rp to lol",second),
                new ProductDTO(3,"2k valorant points",third)
        );
    }

How to inject List of String arrays in spring from properties file?

Yes, By using Spring Expression Language it can be achieved.

Code:

package com.test.listofarray;

import java.util.Arrays;
import java.util.List;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import lombok.extern.slf4j.Slf4j;

@SpringBootApplication
@Slf4j
public class TestApplication implements CommandLineRunner {

    @Value("#{'${LIST_OF_NESTED_ARRAYS}'.split(';')}")
    private List<String[]> list;

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

    }

    @Override
    public void run(String... args) throws Exception {

        list.forEach(array -> log.info("array ----> {}", Arrays.toString(array)));
    }

}

application.properties

LIST_OF_NESTED_ARRAYS=India,USA,Brazil;Asia,Africa

use semi-column(;) to separate the values of each array in the above property and give the same semi-column(;) in the split function inside @value annotation.

Verify the output of the injected list in the below output log.

Output:

2021-11-01 17:48:39.105  INFO 11352 --- [           main] com.resilience.retry.RetryApplication    : No active profile set, falling back to default profiles: default
2021-11-01 17:48:42.184  INFO 11352 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-11-01 17:48:42.206  INFO 11352 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-11-01 17:48:42.207  INFO 11352 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.54]
2021-11-01 17:48:42.411  INFO 11352 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-11-01 17:48:42.411  INFO 11352 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 3235 ms
2021-11-01 17:48:45.139  INFO 11352 --- [           main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 1 endpoint(s) beneath base path '/actuator'
2021-11-01 17:48:45.256  INFO 11352 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2021-11-01 17:48:45.285  INFO 11352 --- [           main] com.resilience.retry.RetryApplication    : Started RetryApplication in 6.946 seconds (JVM running for 7.648)
2021-11-01 17:48:45.397  INFO 11352 --- [           main] com.resilience.retry.RetryApplication    : array ----> [India, USA, Brazil]
2021-11-01 17:48:45.400  INFO 11352 --- [           main] com.resilience.retry.RetryApplication    : array ----> [Asia, Africa]
2021-11-01 17:49:03.860  INFO 11352 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-01 17:49:03.861  INFO 11352 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2021-11-01 17:49:03.862  INFO 11352 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 1 ms

Java : How to load content of .properties file into Properties using spring annotation?

Register your properties file as follows

XML Config

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="
      http://www.springframework.org/schema/beans 
      http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
      http://www.springframework.org/schema/context 
      http://www.springframework.org/schema/context/spring-context-4.2.xsd">

      <context:property-placeholder location="classpath:foo.properties" />

</beans> 

Java Config

@Configuration
@PropertySource("classpath:foo.properties")
public class PropertiesWithJavaConfig {
    //...
}

Using your properties as follows

@Value( "${jdbc.url}" )
private String jdbcUrl;

You can find a complete working solution in my GitHub repository

https://github.com/mirmdasif/springmvc/tree/master/springproperties

How do I load a list of numbers from a spring properties file

Try adding this bean to your configuration:

@Bean 
public ConversionService conversionService() {
    return new DefaultConversionService();
}

It will add support to convert String to Collection:

Note that DefaultConversionService registers converters automatically which are appropriate for most environments. This includes collection converters, scalar converters, and also basic Object to String converters. The same converters can be registered with any ConverterRegistry using the static addDefaultConverters method on the DefaultConversionService class.

Reference: https://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html

How to access a value defined in the application.properties file in Spring Boot

You can use the @Value annotation and access the property in whichever Spring bean you're using

@Value("${userBucket.path}")
private String userBucketPath;

The Externalized Configuration section of the Spring Boot docs, explains all the details that you might need.

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