application.yml alternative in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the alternative properties file in Spring Boot.

Spring Boot

spring.config.name=[1]

Drag options to blanks, or click blank then click option'

Aconfig

Bapplication

Csettings

Dproperties

Attempts:

3 left

💡 Hint

Common Mistakes

Using the full file name including extension instead of just the base name.

Trying to set the file path instead of the config name.

Setting spring.config.name to config tells Spring Boot to look for config.yml or config.properties instead of the default application.yml.

2fill in blank

medium

Complete the code to load an alternative properties file from a specific location.

Spring Boot

spring.config.location=[1]

Drag options to blanks, or click blank then click option'

Aclasspath:/config/

Bclasspath:/application/

Chttp://configserver/

Dfile:./config/

Attempts:

3 left

💡 Hint

Common Mistakes

Using classpath: when the file is outside the classpath.

Omitting the prefix and causing Spring Boot to not find the file.

Using spring.config.location with file:./config/ tells Spring Boot to load config files from the local config folder.

3fill in blank

hard

Fix the error in the command to run Spring Boot with an alternative config file.

Spring Boot

java -jar app.jar --spring.config.name=[1]

Drag options to blanks, or click blank then click option'

Aconfig

Bapplication.yml

Capplication

Dconfig.yml

Attempts:

3 left

💡 Hint

Common Mistakes

Including the file extension in the config name.

Using the default name when trying to override.

The spring.config.name property expects the base name without extension. Using config is correct, not config.yml.

4fill in blank

hard

Fill both blanks to specify multiple config locations in Spring Boot.

Spring Boot

spring.config.location=[1],[2]

Drag options to blanks, or click blank then click option'

Aclasspath:/custom/

Bfile:./config/

Cclasspath:/default/

Dfile:/etc/config/

Attempts:

3 left

💡 Hint

Common Mistakes

Using classpath locations when files are outside the classpath.

Not separating locations with commas.

You can specify multiple config locations separated by commas. Here, file:./config/ and file:/etc/config/ are two local folders Spring Boot will check.

5fill in blank

hard

Fill all three blanks to set an alternative config file name, location, and profile.

Spring Boot

java -jar app.jar --spring.config.name=[1] --spring.config.location=[2] --spring.profiles.active=[3]

Drag options to blanks, or click blank then click option'

Acustomconfig

Bfile:./custom/

Cdev

Dapplication

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up config name and location values.

Forgetting to activate the profile.

This command runs the app with a custom config file base name customconfig, loads config files from file:./custom/, and activates the dev profile.

Practice

1. Which file format is a common alternative to application.yml in Spring Boot for configuration?

easy

A. config.ini

B. config.xml

C. settings.json

D. application.properties

Solution

1. Step 1: Understand Spring Boot configuration files

   Spring Boot supports multiple configuration file formats, but the two most common are application.yml and application.properties.

2. Step 2: Identify the alternative format

   The application.properties file uses simple key=value pairs and is widely used as an alternative to YAML files.

3. Final Answer:

   application.properties -> Option D

4. Quick Check:

   Alternative to application.yml = application.properties [OK]

Hint: Remember: properties files use key=value lines [OK]

Common Mistakes:

• Confusing XML or JSON as default Spring Boot config
• Thinking config.ini is supported by Spring Boot
• Assuming YAML is the only option

2. Which of the following is the correct syntax for setting a server port in application.properties?

easy

A. server.port=8080

B. server.port => 8080

C. server.port : 8080

D. server.port -> 8080

Solution

1. Step 1: Recall properties file syntax

   In application.properties, each configuration is set as a key=value pair without colons or arrows.

2. Step 2: Identify the correct key-value format

   The correct syntax uses an equals sign: server.port=8080.

3. Final Answer:

   server.port=8080 -> Option A

4. Quick Check:

   Properties syntax uses = not : or arrows [OK]

Hint: Properties files always use key=value format [OK]

Common Mistakes:

• Using colon instead of equals sign
• Using arrow symbols which are invalid
• Mixing YAML syntax with properties syntax

3. Given the following application.properties snippet:

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=pass123

What is the effect of this configuration?

medium

A. It sets up a PostgreSQL database connection.

B. It configures a MySQL database connection with the specified URL and credentials.

C. It disables the datasource configuration.

D. It causes a syntax error and fails to start.

Solution

1. Step 1: Analyze the datasource properties

   The keys spring.datasource.url, username, and password configure the database connection details.

2. Step 2: Identify the database type and credentials

   The URL contains jdbc:mysql://, indicating a MySQL database with host localhost and database mydb. Username and password are set accordingly.

3. Final Answer:

   It configures a MySQL database connection with the specified URL and credentials. -> Option B

4. Quick Check:

   Datasource URL with jdbc:mysql = MySQL config [OK]

Hint: Look for jdbc:mysql in URL to identify MySQL config [OK]

Common Mistakes:

• Assuming PostgreSQL from MySQL URL
• Thinking this disables datasource
• Confusing syntax as error

4. You wrote this in application.properties:

server.port9090

Why does your Spring Boot app fail to start on port 9090?

medium

A. Spaces are not allowed anywhere in properties files.

B. Port 9090 is reserved and cannot be used.

C. Missing equals sign between key and value causes syntax error.

D. Property name is incorrect; should be server.port.number.

Solution

1. Step 1: Check properties file syntax

   Each line must have a key and value separated by an equals sign (=) or colon (:).

2. Step 2: Identify the missing equals sign

   The line server.port9090 lacks the equals sign, causing it to be parsed as a single key with no value and preventing the port from being set.

3. Final Answer:

   Missing equals sign between key and value causes syntax error. -> Option C

4. Quick Check:

   Properties need key=value format [OK]

Hint: Always use = or : between key and value [OK]

Common Mistakes:

• Omitting equals sign
• Using wrong property name
• Assuming spaces are forbidden everywhere

5. You want to migrate your Spring Boot app configuration from application.yml to application.properties. Which of the following is the correct way to convert this YAML snippet?

server:
  port: 9090
spring:
  datasource:
    url: jdbc:h2:mem:testdb
    username: sa
    password: ""

hard

A. server.port=9090
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=

B. server.port : 9090
spring.datasource.url : jdbc:h2:mem:testdb
spring.datasource.username : sa
spring.datasource.password : ""

C. server.port => 9090
spring.datasource.url => jdbc:h2:mem:testdb
spring.datasource.username => sa
spring.datasource.password => ""

D. server.port9090
spring.datasource.urljdbc:h2:mem:testdb
spring.datasource.usernamesa
spring.datasource.password""

Solution

1. Step 1: Understand YAML to properties conversion

   YAML uses indentation and colons, while properties files use dot notation and equals signs.

2. Step 2: Convert nested YAML keys to dot notation with =

   The nested keys become dot-separated keys, and values are assigned with equals signs. Empty password is represented by an empty value.

3. Final Answer:

   server.port=9090 spring.datasource.url=jdbc:h2:mem:testdb spring.datasource.username=sa spring.datasource.password= -> Option A

4. Quick Check:

   YAML nesting = dot notation + = in properties [OK]

Hint: Convert YAML nesting to dot keys with = [OK]

Common Mistakes:

• Using colon instead of equals in properties
• Using arrows or spaces instead of =
• Not converting nested keys to dot notation