JAVA EE: How to Inject List having Dependent Object using Spring dependency injection by constructor?

Friday 25 May 2018

How to Inject List having Dependent Object using Spring dependency injection by constructor?

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How to Inject List having Dependent Object using Spring dependency injection by constructor?

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%20http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.2.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 dependencies -->

        <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>

    </dependencies>

</project>

Fruit.java

package com.ram.model;

public class Fruit

{

    private String name;

    private String color;

    public Fruit(String name, String color)

    {

        System.out.println("Fruit(String name, String color) "

                + "constructor is called by the Spring container");

        this.name = name;

        this.color = color;

    }

    @Override

    public String toString()

    {

        return "Fruit [name=" + name + ", color=" + color + "]";

    }

}

FruitShop.java

package com.ram.core;

import java.util.List;

import com.ram.model.Fruit;

public class FruitShop

{

    private String shopName;

    private List<Fruit> listOfAvailableFruits;

    public FruitShop(String shopName, List<Fruit> listOfAvailableFruits)

    {

        System.out.println(

                "FruitShop(String shopName, List<Fruit> listOfAvailableFruits) "

                        + "constructor is called by the Spring container");

        this.shopName = shopName;

        this.listOfAvailableFruits = listOfAvailableFruits;

    }

    public void displayFruitShopInfo()

    {

        System.out.println("FruitShop [shopName=" + shopName

                + ", listOfAvailableFruits=" + listOfAvailableFruits + "]");

    }

}

applicationContext.xml

<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-4.3.xsd">

    <bean id="fruit1" class="com.ram.model.Fruit">

        <constructor-arg type="String" value="Apple"></constructor-arg>

        <constructor-arg type="String" value="Red"></constructor-arg>

    </bean>

    <bean id="fruit2" class="com.ram.model.Fruit">

        <constructor-arg type="String" value="Grapes"></constructor-arg>

        <constructor-arg type="String" value="Violet"></constructor-arg>

    </bean>

    <bean id="fruitShop" class="com.ram.core.FruitShop">

        <constructor-arg type="String" value="Fruit Mart"></constructor-arg>

        <constructor-arg type="java.util.List">

            <list>

                <ref bean="fruit1" />

                <ref bean="fruit2" />

            </list>

        </constructor-arg>

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        FruitShop fruitShop = (FruitShop) context.getBean("fruitShop");

        System.out.println(

                "Got fruitShop object from the ApplicationContext(Spring Container)");

        fruitShop.displayFruitShopInfo();

    }

}

Output

Apr 26, 2018 9:42:33 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Thu Apr 26 09:42:33 IST 2018]; root of context hierarchy

Apr 26, 2018 9:42:34 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

Fruit(String name, String color) constructor is called by the Spring container

Fruit(String name, String color) constructor is called by the Spring container

FruitShop(String shopName, List<Fruit> listOfAvailableFruits) constructor is called by the Spring container

---------------------------------------

Got fruitShop object from the ApplicationContext(Spring Container)

FruitShop [shopName=Fruit Mart, listOfAvailableFruits=[Fruit [name=Apple, color=Red], Fruit [name=Grapes, color=Violet]]]