Environment variables in configuration in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read an environment variable in Spring Boot application.properties.

Spring Boot

server.port=[1]

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

A${PORT}

BPORT

C$PORT

D${PORT:8080}

Attempts:

3 left

💡 Hint

Common Mistakes

Using $PORT without braces

Not providing default value

Using plain PORT without ${}

In Spring Boot, you use ${VAR:default} syntax to read environment variables with a default value.

2fill in blank

medium

Complete the annotation to inject an environment variable into a Spring Boot component.

Spring Boot

@Value("[1]")
private String dbUrl;

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

A"${DATABASE_URL:jdbc:h2:mem:testdb}"

B"DATABASE_URL"

C"$DATABASE_URL"

D"${DATABASE_URL}"

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting ${} syntax

Not adding quotes around the string

Using $ without braces

The @Value annotation uses ${} syntax and can include a default value after a colon.

3fill in blank

hard

Fix the error in this Spring Boot configuration to correctly use environment variables with default values.

Spring Boot

spring.datasource.url=[1]

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

ADB_URL:jdbc:mysql://localhost:3306/mydb

B$DB_URL:jdbc:mysql://localhost:3306/mydb

C${DB_URL:jdbc:mysql://localhost:3306/mydb}

D${DB_URL, jdbc:mysql://localhost:3306/mydb}

Attempts:

3 left

💡 Hint

Common Mistakes

Using $ without braces

Using comma instead of colon

Omitting ${} syntax

The correct syntax uses ${VAR:default} with a colon to separate variable and default.

4fill in blank

hard

Fill both blanks to define a Spring Boot property that reads an environment variable with a fallback and inject it using @Value.

Spring Boot

@Value("[1]")
private String apiKey;

# application.properties
external.api.key=[2]

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

A"${API_KEY:defaultKey}"

B${API_KEY:defaultKey}

C"${EXTERNAL_API_KEY:defaultKey}"

D${EXTERNAL_API_KEY:defaultKey}

Attempts:

3 left

💡 Hint

Common Mistakes

Missing quotes in @Value

Adding quotes in properties file

Using wrong variable names

Use quotes and ${} syntax in @Value, and plain ${} syntax in properties file without quotes.

5fill in blank

hard

Fill all three blanks to create a configuration class that reads environment variables with defaults using @Value and exposes them as beans.

Spring Boot

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class AppConfig {

    @Value("[1]")
    private String host;

    @Value("[2]")
    private int port;

    @Bean
    public String serviceUrl() {
        return "http://" + host + ":" + [3];
    }
}

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

A${SERVICE_HOST:localhost}

B${SERVICE_PORT:8080}

Cport

Dhost

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes incorrectly

Using variable names instead of ${} in @Value

Using host instead of port in return

Use @Value with ${VAR:default} syntax for host and port, then use the port variable in the bean method.