Spring Data JPA CrudRepository count() Example

In this tutorial, we will see about Spring Data CrudRepository count() Example using Spring Boot and Oracle.

Spring Data JPA Interview Questions and Answers
How to write a custom method in the repository in Spring Data JPA

CrudRepository interface extends Repository interface. In Spring Data JPA Repository is top-level interface in hierarchy. Here we are going to see count() method of CrudRepository. The count() method has been defined as below.

long count();

The CrudRepository count() method returns the number of entities available in database. Internally count() method uses EntityManger’s createQuery() method.

	public long count() {
		return em.createQuery(getCountQueryString(), Long.class).getSingleResult();
	}

Let’s see in below code how we are going to use the CrudRepository count() method.

package com.javatute.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.javatute.entity.Student;
import com.javatute.repository.StudentRepository;
import com.javatute.service.StudentService;

@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {

	@Autowired
	private StudentRepository studentRepository;

	@Transactional
	public List<Student> saveAllStudent(List<Student> studentList) {
		List<Student> response = (List<Student>) studentRepository.saveAll(studentList);
		return response;
	}

	@Transactional(readOnly = true)
	public long getCountOfEntities() {
		long count = studentRepository.count();
		return count;
	}
}

Query generated in case of CrudRepository count() method.

Hibernate: select count(*) as col_0_0_ from student student0_

Let’s see an example of Spring Data JPA CrudRepository count() Method.

Open eclipse and create maven project, Don’t forget to check ‘Create a simple project (skip)’ click on next.  Fill all details(GroupId – springdatacount, ArtifactId – springdatacount and name – springdatacount) and click on finish. Keep packaging as the jar.

Modify pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>springdatacount</groupId>
	<artifactId>springdatacount</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springdatacount</name>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.2.RELEASE</version>
	</parent>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>

		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>com.oracle</groupId>
			<artifactId>ojdbc6</artifactId>
			<version>11.2.0.3</version>
		</dependency>

	</dependencies>
	<build>
		<finalName>${project.artifactId}</finalName>
		<plugins>

			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<fork>true</fork>
					<executable>C:\Program Files\Java\jdk1.8.0_131\bin\javac.exe</executable>
				</configuration>
			</plugin>


		</plugins>
	</build>
</project>

Note – In pom.xml we have defined javac.exe path in configuration tag. You need to change accordingly i.e where you have installed JDK.

If you see any error for oracle dependency then follow these steps.

Directory structure.

Student.java

package com.javatute.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Student {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;

	@Column(name = "name")
	private String name;

	@Column(name = "roll_number")
	private String rollNumber;

	@Column(name = "university")
	String university;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getRollNumber() {
		return rollNumber;
	}

	public void setRollNumber(String rollNumber) {
		this.rollNumber = rollNumber;
	}

	public String getUniversity() {
		return university;
	}

	public void setUniversity(String university) {
		this.university = university;
	}

}

StudentController.java

package com.javatute.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.javatute.entity.Student;
import com.javatute.service.StudentService;

@RestController
@RequestMapping(value = "/student")
public class StudentController {

	@Autowired
	private StudentService studentService;

	@RequestMapping(value = "/saveall", method = RequestMethod.POST)
	@ResponseBody
	public List<Student> saveAllStudents(@RequestBody List<Student> studentList) {
		List<Student> studentResponse = (List<Student>) studentService.saveAllStudent(studentList);
		return studentResponse;
	}

	@RequestMapping(value = "/count", method = RequestMethod.GET)
	@ResponseBody
	public long countEntities() {
		long count = studentService.getCountOfEntities();
		return count;
	}

}

StudentRepository.java – interface

package com.javatute.repository;

import java.io.Serializable;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.javatute.entity.Student;

@Repository
public interface StudentRepository extends CrudRepository<Student, Serializable> {

}

StudentService.java – interface

package com.javatute.service;

import java.util.List;

import org.springframework.stereotype.Component;

import com.javatute.entity.Student;

@Component
public interface StudentService {
	public List<Student> saveAllStudent(List<Student> studentList);

	public long getCountOfEntities();

}

StudentServiceImpl.java

package com.javatute.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.javatute.entity.Student;
import com.javatute.repository.StudentRepository;
import com.javatute.service.StudentService;

@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {

	@Autowired
	private StudentRepository studentRepository;

	@Transactional
	public List<Student> saveAllStudent(List<Student> studentList) {
		List<Student> response = (List<Student>) studentRepository.saveAll(studentList);
		return response;
	}

	@Transactional(readOnly = true)
	public long getCountOfEntities() {
		long count = studentRepository.count();
		return count;
	}
}

SpringMain.java

package com.javatute.main;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages = "com.*")
@EntityScan("com.javatute.entity")
public class SpringMain {
	public static void main(String[] args) {

		SpringApplication.run(SpringMain.class, args);
	}

}

JpaConfig.java

package com.javatute.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration
@EnableJpaRepositories(basePackages = "com.javatute.repository")
public class JpaConfig {

}

application.properties

# Connection url for the database
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE
spring.datasource.username=SYSTEM
spring.datasource.password=oracle2
spring.datasource.driver-class-name=oracle.jdbc.driver.OracleDriver
# Show or not log for each sql query
spring.jpa.show-sql = true
 
 
spring.jpa.hibernate.ddl-auto =create
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.Oracle10gDialect
 
server.port = 9091

Let’s run the SpringMain class(run as java application).

Perform save operation first using below REST API.

Perform save operation first using below REST API.

http://localhost:9091/student/saveall

Request Data –

[
    {
        "name": "Hiteshdo",
        "rollNumber": "0126CS01",
        "university":"rgtu"
    },
    {
        "name": "Johnhjhjhjhj",
        "rollNumber": "0126CS02",
        "university":"rgtu"
    },
    {
        "name": "Mohankkkkkkkkkkkkkk",
        "rollNumber": "0126CS03",
        "university":"rgtu"
    },
    {
        "name": "Nagesh",
        "rollNumber": "0126CS04",
        "university":"rgtu"
    },
    {
        "name": "s",
        "rollNumber": "0126CS05",
        "university":"rgtu"
    },
    {
        "name": "Ranakum",
        "rollNumber": "0126CS06",
        "university":"rgtu"
    },
    {
        "name": "Roc",
        "rollNumber": "0126CS07",
        "university":"rgtu"
    },
    {
        "name": "Simpy",
        "rollNumber": "0126CS08",
        "university":"rgtu"
    },
    {
        "name": "Tiwari",
        "rollNumber": "0126CS09",
        "university":"rgtu"
    },    {
        "name": "Appu",
        "rollNumber": "0126CS10",
        "university":"rgtu"
    },
    {
        "name": "Babloo",
        "rollNumber": "0126CS11",
        "university":"rgtu"
    },
    {
        "name": "Ga",
        "rollNumber": "0126CS12",
        "university":"rgtu"
    }
]

Response data –

[
    {
        "id": 1,
        "name": "Hiteshdo",
        "rollNumber": "0126CS01",
        "university": "rgtu"
    },
    {
        "id": 2,
        "name": "Johnhjhjhjhj",
        "rollNumber": "0126CS02",
        "university": "rgtu"
    },
    {
        "id": 3,
        "name": "Mohankkkkkkkkkkkkkk",
        "rollNumber": "0126CS03",
        "university": "rgtu"
    },
    {
        "id": 4,
        "name": "Nagesh",
        "rollNumber": "0126CS04",
        "university": "rgtu"
    },
    {
        "id": 5,
        "name": "s",
        "rollNumber": "0126CS05",
        "university": "rgtu"
    },
    {
        "id": 6,
        "name": "Ranakum",
        "rollNumber": "0126CS06",
        "university": "rgtu"
    },
    {
        "id": 7,
        "name": "Roc",
        "rollNumber": "0126CS07",
        "university": "rgtu"
    },
    {
        "id": 8,
        "name": "Simpy",
        "rollNumber": "0126CS08",
        "university": "rgtu"
    },
    {
        "id": 9,
        "name": "Tiwari",
        "rollNumber": "0126CS09",
        "university": "rgtu"
    },
    {
        "id": 10,
        "name": "Appu",
        "rollNumber": "0126CS10",
        "university": "rgtu"
    },
    {
        "id": 11,
        "name": "Babloo",
        "rollNumber": "0126CS11",
        "university": "rgtu"
    },
    {
        "id": 12,
        "name": "Ga",
        "rollNumber": "0126CS12",
        "university": "rgtu"
    }
]

Let’s get the count of student entities using CrudRepository count() method.

GET API – http://localhost:9091/student/count

Count should come 12 as we have saved 12 entities.

That’s all about Spring Data JPA CrudRepository count() Example.

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Other Spring Data JPA and Hibernate tutorials.

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• Hibernate Table Per Concrete Class Spring Boot.
• Hibernate Table Per Subclass Inheritance Spring Boot.
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• One To One Mapping Annotation Example in Hibernate/JPA using Spring Boot and Oracle.
• One To One Bidirectional Mapping Example In Hibernate/JPA Using Spring Boot and Oracle.
• One To Many Mapping Annotation Example In Hibernate/JPA Using Spring Boot And Oracle.
• Many To One Unidirectional Mapping In Hibernate/JPA Annotation Example Using Spring Boot and Oracle.
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Spring Data JPA CrudRepository() docs.