Merge pull request #13353 from amit88265/collections-vs-stream

BAEL-5953 - Added code of collections-vs-stream

persistence-modules/spring-data-jpa-query-3/pom.xml

@@ -5,6 +5,9 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>spring-data-jpa-query-3</artifactId>
     <name>spring-data-jpa-query-3</name>
+    <properties>
+        <javafaker.version>0.15</javafaker.version>
+    </properties>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -22,6 +25,11 @@
             <groupId>com.h2database</groupId>
             <artifactId>h2</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.github.javafaker</groupId>
+            <artifactId>javafaker</artifactId>
+            <version>${javafaker.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>

persistence-modules/spring-data-jpa-query-3/src/main/java/com/baeldung/spring/data/jpa/collectionsvsstream/ListVsStreamQueryApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.spring.data.jpa.collectionsvsstream;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class ListVsStreamQueryApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(ListVsStreamQueryApplication.class, args);
+    }
+}

persistence-modules/spring-data-jpa-query-3/src/main/java/com/baeldung/spring/data/jpa/collectionsvsstream/User.java

@@ -0,0 +1,61 @@
+package com.baeldung.spring.data.jpa.collectionsvsstream;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "_user")
+public class User {
+    private String firstName;
+    private String lastName;
+    private int age;
+    @Id
+    private int id;
+
+    public User() {
+    }
+
+    public User(String firstName, String lastName, int age) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+    }
+
+    public User(String firstName, String lastName, int age, int id) {
+        this(firstName, lastName, age);
+        this.id = id;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+}

persistence-modules/spring-data-jpa-query-3/src/main/java/com/baeldung/spring/data/jpa/collectionsvsstream/UserRepository.java

@@ -0,0 +1,14 @@
+package com.baeldung.spring.data.jpa.collectionsvsstream;
+
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface UserRepository extends JpaRepository<User, String> {
+  Stream<User> findAllByAgeGreaterThan(int age);
+
+  List<User> findByAgeGreaterThan(int age);
+}

persistence-modules/spring-data-jpa-query-3/src/test/java/com/baeldung/spring/data/jpa/collectionsvsstream/UserRepositoryUnitTest.java

@@ -0,0 +1,58 @@
+package com.baeldung.spring.data.jpa.collectionsvsstream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+
+import com.github.javafaker.Faker;
+
+@DataJpaTest
+class UserRepositoryUnitTest {
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @BeforeEach
+    public void setup() {
+        Faker faker = new Faker();
+        List<User> people = IntStream.range(1, 100)
+          .parallel()
+          .mapToObj(i -> new User(faker.name()
+            .firstName(), faker.name()
+            .lastName(), faker.number()
+            .numberBetween(1, 100), i))
+          .collect(Collectors.toList());
+        userRepository.saveAll(people);
+    }
+
+    @AfterEach
+    public void tearDown() {
+        userRepository.deleteAll();
+    }
+
+    @Test
+    public void whenAgeIs20_thenItShouldReturnAllUsersWhoseAgeIsGreaterThan20InAList() {
+        List<User> users = userRepository.findByAgeGreaterThan(20);
+        assertThat(users).isNotEmpty();
+        assertThat(users.stream()
+          .map(User::getAge)
+          .allMatch(age -> age > 20)).isTrue();
+    }
+
+    @Test
+    public void whenAgeIs20_thenItShouldReturnAllUsersWhoseAgeIsGreaterThan20InAStream() {
+        Stream<User> users = userRepository.findAllByAgeGreaterThan(20);
+        assertThat(users).isNotNull();
+        assertThat(users.map(User::getAge)
+          .allMatch(age -> age > 20)).isTrue();
+    }
+}