Spring-Boot appication.properties file location interview question: Part 1

Guys,
Here i wanted to discuss one of the tricky interview quetion related to location of application.properties file for spring-boot and microservice interview.

The question is
“Which file will be used by spring boot if one file(application.properties) is present at your src/main/resources path inside the jar and one more file present parallel to your jar file in file system ?”

Here are some tips for properties file usage in spring boot.

Spring boot will auto detected the application.properties file from src/main/resources and we can use all properties from that file.

Below is our sample application.properties file.

application.properties

name=Vishal

Below is my DemoController.java class which access my application.properties file value.

DemoController.java

@RestController
public class DemoController {

@Value("${name}")
String name;

 @RequestMapping("/hello")
 public String sayHello() {
      return" Hello " + name;
 }

}

Once you run the project and hit the below url in browser, the output ill be Hello Vishal.

http://localhost:8080/hello

output:

Hello Vishal

So spring will access the application.properties from src/main/resources folder.

Now generate the jar file using maven command mvn clen install.

Afte generating jar copy the jar file into another folder and create another application.properties file parallel to copied jar file.

Below is my folder structure where my jar file and another application.properties file are available at same place.

Below is my new application.properties with updated property value.

application.properties

name=Yogesh

Here in my jar file contains application.properties file  and the same folder where my “jar” file present i have another application.properties file.

So let’s run the project in command prompt using below command.

java -jar PropertyFileTest-0.0.1-SNAPSHOT.jar

Now again run the projet and hit the below url in browser, the output ill be Hello Yogesh.

http://localhost:8080/hello

output: 

Hello Yogesh

So here spring boot is accessing application.properties which is available in same folder where our “jar” file available.

means spring is ignoring the application.properties file which is available at src/main/resource

.
Hope, this will help to answer the interview question
Happy learning.

Thanks,
Vishal Ranapariya