Add JPA and H2

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Goal

Add the Spring Data JPA, H2, and Bean Validation dependencies to the beginner project and configure an in-memory datasource. After this page the project compiles with the new dependencies on the classpath.

Prerequisites

• Why a database

Add three dependencies to pom.xml

Open pom.xml in the beginner project and add the three blocks below inside the <dependencies> section (order inside the section does not matter):

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
  <scope>runtime</scope>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

What each one does:

• spring-boot-starter-data-jpa — pulls in Hibernate (the JPA implementation), Spring Data JPA repository support, and Spring's transaction management.
• h2 — the in-memory relational database; runtime scope means it is on the classpath at runtime but not needed to compile your own code.
• spring-boot-starter-validation — pulls in the Jakarta Bean Validation API and Hibernate Validator so you can use @NotBlank, @Valid, and related annotations.

All version numbers are managed by the Spring Boot parent POM you already have. You do not need to specify versions.

Configure the datasource

Open src/main/resources/application.properties and add:

spring.datasource.url=jdbc:h2:mem:items
spring.jpa.hibernate.ddl-auto=update

What each line does:

• spring.datasource.url=jdbc:h2:mem:items — tells Spring Boot to connect to an in-memory H2 database named items. The data exists only while the JVM is running. No password or username is needed; H2 defaults to sa with no password for in-memory instances.
• spring.jpa.hibernate.ddl-auto=update — tells Hibernate to create or update the database schema automatically from your @Entity classes on startup. In production you would use validate or manage schema separately with a migration tool like Flyway.

Verify: project compiles

Run:

./mvnw compile

Expected output (last lines):

BUILD SUCCESS

Maven downloads the new dependencies on the first run. Subsequent runs are fast.

If you see BUILD FAILURE, check that you placed the <dependency> blocks inside <dependencies> and not inside <dependencyManagement>.

Next → Entity and repository