CODEWITHSUNDEEP
spring
Jay Josh
Jay Josh

Reputation: 11

Setter method dont have any effect when bean scope changed to 'prototype'

I have following classes defined in spring project

Triangle.java

public class Triangle 
{

    private double breadth;
    private double length;

    public double getBreadth() {
        return breadth;
    }

    public void setBreadth(double breadth) {
        this.breadth = breadth;
    }

    public double getLength() {
        return length;
    }

    public void setLength(double length) {
        this.length = length;
    }
}

Below class calculates the area of triangle

Area.java


public class Area 
{
    Triangle triangle;

    public Triangle getTriangle() {
        return triangle;
    }

    public void setTriangle(Triangle triangle) {
        this.triangle = triangle;
    }

    public double triArea()
    {
        return (triangle.getBreadth() * triangle.getLength())/2;
    }
}

spring.xml configuration file is shown below

spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd
/spring-beans-2.0.dtd">

<beans>
    <bean id="triangle" class="src.jayant.spring.Triangle" scope="prototype">
        <property name = "breadth" value = "20"/>
        <property name = "length" value = "20"/> 
    </bean>

    <bean id="area" class="src.jayant.spring.Area">
        <property name = "triangle" ref="triangle"/>
    </bean>

</beans>

Finally we have AreaApp.java which gets both 'area' and 'triangle' beans defined in the xml and calculates the area.

AreaApp.java

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;                                                                                           

public class AreaApp 
{
    public static void main(String args [])
    {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");

        Triangle triangle = (Triangle)context.getBean("triangle");
        Area area = (Area)context.getBean("area");

        System.out.println("Area of Triangle is : "+area.triArea());

        triangle.setBreadth(40);

        System.out.println("Area of Triangle is : "+area.triArea());
    }
}

Now

When we have 'triangle' bean scope as 'singleton' 

<bean id="triangle" class="src.jayant.spring.Triangle" scope="singleton">

then output will be 

Area of Triangle is : 200.0
Area of Triangle is : 400.0

but when I change scope to 'prototype' 

<bean id="triangle" class="src.jayant.spring.Triangle" scope="prototype">

then output will be 

Area of Triangle is : 200.0
Area of Triangle is : 200.0

Why the setter method

triangle.setBreadth(40);

have no effect when bean scope is prototype.

Thanks

Jay

Upvotes: 0

Views: 230

Answers (1)

JB Nizet
JB Nizet

Reputation: 691685

It does have an effect: it changes the breadth of the triangle you got from the context.

But this triangle is not the same triangle as the one used by the Area bean, since your triangle bean is now a prototype, and thus, by definition of the prototype scope, you get a new instance every time you ask a Triangle instance to the context.

Upvotes: 3

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