Collection element set in Spring

With this example we will show you how to inject Collections in Spring Bean set.

In order to show how Collections can be injected in a Spring Bean we will create a simple Spring Bean with a property Set.

If you already have an idea on how to create a maven project in Eclipse will be great otherwise I will tell you here how to create a maven project in Eclipse.
Prerequisites

The following things are required in order to run the application
Eclipse Kepler
JDK 1.8
Have maven 3 installed and configured
Spring dependencies in pom.xml

Now we will see the below steps how to create a maven based spring project in Eclipse

Step 1. Create a standalone maven project in Eclipse

Go to File -> New -> Other. On popup window under Maven select Maven Project. Then click on Next. Select the workspace location – either default or browse the location. Click on Next. Now in next window select the row as highlighted from the below list of archtypes and click on Next button.

maven-arctype-quickstart
Now enter the required fields (Group Id, Artifact Id) as shown below
Group Id : com.roytuts
Artifact Id : spring-faqs
Step 2. Modify the pom.xml file as shown below.

<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>com.roytuts</groupId>
    <artifactId>spring-faqs</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>spring-faqs</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <jdk.version>1.8</jdk.version>
        <junit.version>4.11</junit.version>
        <spring.version>4.1.5.RELEASE</spring.version>
    </properties>
    <dependencies>
        <!-- Spring framework -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>${jdk.version}</source>
                    <target>${jdk.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Step 3. If you see JRE System Library[J2SE-1.4] then change the version by below process

Do right-click on the project and go to Build -> Configure build path, under Libraries tab click on JRE System Library[J2SE-1.4], click on Edit button and select the appropriate jdk 1.8 from the next window. Click on Finish then Ok.

Step 4. Create src/main/resources folder for putting the resource files.

Do right-click on the project and go New -> Source Folder. Give Folder name: as src/main/resources and click on Finish button.

Step 5. Create an XML properties file under src/main/resources.

Do right-click on src/main/resources in the project and go New -> file. Give File name: as applicationContext.xml and click on Finish button.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="springCollection" class="com.roytuts.spring.collection.SpringCollection">
        <property name="set">
            <set>
                <value>just some string</value>
                <value>another some string</value>
                <value>more value string</value>
            </set>
        </property>
    </bean>
</beans>

Step 6. Create a POJO class that contains list element

package com.roytuts.spring.collection;
import java.util.Map;
public class SpringCollection {
    private Set<String> set;
    public Set<String> getSet() {
        return set;
    }
    public void setSet(Set<String> set) {
        this.set = set;
    }
}

Step 7. Create a Test class which will test our code how it works

package com.roytuts.spring.collection;
import java.util.Set;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringCollectionTest {
    private SpringCollection springCollection;
    @Before
    public void setUp() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                "applicationContext.xml");
        springCollection = applicationContext.getBean("springCollection",
                SpringCollection.class);
    }
    @Test
    public void displaySet() {
        Set<String> set = springCollection.getSet();
        for (String string : set) {
            System.out.println(string);
        }
    }
}

Step 8. Run the above test class, you will get below output

just some string
another some string
more value string

That’s all. Thanks for reading.