Spring Boot findAll

last modified July 18, 2023

Spring Boot findAll shows how to retrieve all entities using findAll method of the CrudRepository.

Spring is a popular Java/Kotlin application framework for creating enterprise applications. Spring Boot is an evolution of Spring framework which helps create stand-alone, production-grade Spring based applications with minimal effort.

CrudRepository

CrudRepository interface provides generic CRUD operations on a repository for a specific type. Its findAll method retrieves all entities of the type.

Spring Boot findAll example

The following application sets up a repository of City objects. In the console runner we retrieve city objects by their Ids.

build.gradle
...
src
├── main
│ ├── java
│ │ └── com
│ │ └── zetcode
│ │ ├── Application.java
│ │ ├── MyRunner.java
│ │ ├── model
│ │ │ └── City.java
│ │ ├── repository
│ │ │ └── CityRepository.java
│ │ └── service
│ │ ├── CityService.java
│ │ └── ICityService.java
│ └── resources
│ ├── application.properties
│ ├── data-h2.sql
│ └── schema-h2.sql
└── test
 ├── java
 └── resources

This is the project structure.

plugins {
 id 'org.springframework.boot' version '3.1.1'
 id 'io.spring.dependency-management' version '1.1.0'
 id 'java'
}
group = 'com.zetcode'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'
repositories {
 mavenCentral()
}
dependencies {
 implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
 runtimeOnly 'com.h2database:h2'
}

The build.gradle file contains dependencies for Spring Data JPA and H2 database.

spring.main.banner-mode=off
spring.sql.init.platform=h2
spring.jpa.hibernate.ddl-auto=none

The application.properties is Spring Boot's main configuration file. The Spring Boot banner is turned off with the spring.main.banner-mode property.

The spring.sql.init.platform sets the vendor name of the database. It is used in the initialization scripts. The spring.jpa.hibernate.ddl-auto disables the automatic creation of schemas from entities.

CREATE TABLE cities(id INT PRIMARY KEY AUTO_INCREMENT,
 name VARCHAR(255), population INT);

When the application is started, the schema-h2.sql script is executed. It creates a new database table.

INSERT INTO cities(name, population) VALUES('Bratislava', 432000);
INSERT INTO cities(name, population) VALUES('Budapest', 1759000);
INSERT INTO cities(name, population) VALUES('Prague', 1280000);
INSERT INTO cities(name, population) VALUES('Warsaw', 1748000);
INSERT INTO cities(name, population) VALUES('Los Angeles', 3971000);
INSERT INTO cities(name, population) VALUES('New York', 8550000);
INSERT INTO cities(name, population) VALUES('Edinburgh', 464000);
INSERT INTO cities(name, population) VALUES('Suzhou', 4327066);
INSERT INTO cities(name, population) VALUES('Zhengzhou', 4122087);
INSERT INTO cities(name, population) VALUES('Berlin', 3671000);

The table is filled with data from the data-h2.sql file.

package com.zetcode.model;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import java.util.Objects;
@Entity
@Table(name = "cities")
public class City {
 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 private Long id;
 private String name;
 private int population;
 public City() {
 }
 public City(String name, int population) {
 this.name = name;
 this.population = population;
 }
 public Long getId() {
 return id;
 }
 public void setId(Long id) {
 this.id = id;
 }
 public String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }
 public int getPopulation() {
 return population;
 }
 public void setPopulation(int population) {
 this.population = population;
 }
 @Override
 public boolean equals(Object o) {
 if (this == o) return true;
 if (o == null || getClass() != o.getClass()) return false;
 City city = (City) o;
 return population == city.population &&
 Objects.equals(name, city.name);
 }
 @Override
 public int hashCode() {
 return Objects.hash(name, population);
 }
 @Override
 public String toString() {
 var builder = new StringBuilder();
 builder.append("City{id=").append(id).append(", name=")
 .append(name).append(", population=")
 .append(population).append("}");
 return builder.toString();
 }
}

This is the City entity.

package com.zetcode.repository;
import com.zetcode.model.City;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface CityRepository extends CrudRepository<City, Long> {
}

By extending from the Spring CrudRepository, we have some basic methods for our data repository implemented.

package com.zetcode.service;
import com.zetcode.model.City;
public interface ICityService {
 Iterable<City> findAll();
}

ICityService provides a contract method to retrieve all cities.

package com.zetcode.service;
import com.zetcode.model.City;
import com.zetcode.repository.CityRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class CityService implements ICityService {
 private final CityRepository cityRepository;
 @Autowired
 public CityService(CityRepository cityRepository) {
 this.cityRepository = cityRepository;
 }
 @Override
 public Iterable<City> findAll() {
 return cityRepository.findAll();
 }
}

CityService contains the implementation of the findAll method. We use the repository to retrieve data from the database.

private final CityRepository cityRepository;
@Autowired
public CityService(CityRepository cityRepository) {
 this.cityRepository = cityRepository;
}

CityRepository is injected.

@Override
public Iterable<City> findAll() {
 return cityRepository.findAll();
}

The findAll returns the Iterable<City>.

package com.zetcode;
import com.zetcode.service.ICityService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
@Component
public class MyRunner implements CommandLineRunner {
 private final ICityService cityService;
 @Autowired
 public MyRunner(ICityService cityService) {
 this.cityService = cityService;
 }
 @Override
 public void run(String... args) throws Exception {
 var cities = cityService.findAll();
 cities.forEach(System.out::println);
 }
}

In the MyRunner we retrieve all cities.

var cities = cityService.findAll();
cities.forEach(System.out::println);

We get all cities and print them to the console.

package com.zetcode;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
 public static void main(String[] args) {
 SpringApplication.run(Application.class, args);
 }
}

The Application sets up the Spring Boot application. The @SpringBootApplication enables auto-configuration and component scanning.

$ ./gradlew bootRun
...
City(id=1, name='Bratislava', population=432000)
City(id=2, name='Budapest', population=1759000)
City(id=3, name='Prague', population=1280000)
City(id=4, name='Warsaw', population=1748000)
City(id=5, name='Los Angeles', population=3971000)
City(id=6, name='New York', population=8550000)
City(id=7, name='Edinburgh', population=464000)
City(id=8, name='Suzhou', population=4327066)
City(id=9, name='Zhengzhou', population=4122087)
City(id=10, name='Berlin', population=3671000)
...

We run the application.

In this article we have showed how to find all entities using CrudRepository's findAll method.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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