application.properties structure in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the application.properties file in a Spring Boot project?

It is used to configure application settings like server port, database connection, and other properties in a simple key-value format.

beginner

How are properties structured inside application.properties?

Properties are written as key-value pairs separated by an equals sign, for example: <br>server.port=8080

intermediate

How can you organize properties for different environments using application.properties?

You create separate files like application-dev.properties or application-prod.properties and activate them via the spring.profiles.active property.

intermediate

What is the difference between application.properties and application.yml?

application.properties uses simple key-value pairs, while application.yml uses YAML format which supports nested structures and is more readable for complex configs.

beginner

Can you use comments in application.properties? How?

Yes, comments start with a hash symbol #. Anything after # on the line is ignored by Spring Boot.

What symbol separates keys and values in application.properties?

A ,

B :

C -

D =

In application.properties, keys and values are separated by an equals sign =.

How do you activate a specific profile in Spring Boot?

A spring.profiles.active=profileName

B profile.active=spring

C spring.active.profile=profileName

D active.profile=spring

You set spring.profiles.active=profileName in application.properties to activate a profile.

Which file format supports nested configuration better?

A application.yml

B application.xml

C application.properties

D application.json

application.yml supports nested structures better than application.properties.

How do you write a comment in application.properties?

A // This is a comment

B <!-- This is a comment -->

C # This is a comment

D /* This is a comment */

Comments start with # in application.properties.

What would this line do? server.port=9090

A Sets the database port to 9090

B Sets the server port to 9090

C Starts the server on port 80

D Disables the server

This sets the Spring Boot server to listen on port 9090.

Explain the structure and purpose of the application.properties file in Spring Boot.

Think about how you tell your app what settings to use.

Describe how to manage different environments using application.properties files.

Consider how you might have different settings for testing and production.