CODEWITHSUNDEEP
javaspring
Raymond
Raymond

Reputation: 572

Spring init methods

I'm learning spring and I got confused in init, destroy method and constructor part

This is spring-config.xml

   <bean id="msgBean" class="com.example1.MessagesBean" init-method="start">

    </bean>  

    <bean name="carBean" class="com.example2.Car" init-method="initEngine">
        <constructor-arg ref="engineBean" />
    </bean>

    <bean id="engineBean" class="com.example2.Engine" />

This is Car.java

public class Car {

    private Engine engine;

    public Car(Engine engine){
        System.out.println("Inside Car constructor");
        this.engine = engine;
    }

    public void startCarEngine(){
        engine.startEngine();
    }

    private void initEngine(){
        System.out.println("heating up engine");
    }
}

This is Engine.java

public class Engine {

    public Engine(){
        System.out.println("Inside Engine constructor");
    }

    public void startEngine(){
        System.out.println("Engine is starting...");
    }
}

This is MessageBean.java

public class MessagesBean {

    private static final String HELLO_WORLD = "Hello World";

    public MessagesBean(){
        System.out.println("Printing " + HELLO_WORLD);
    }


    public void start(){
        System.out.println("Step 2.Bean is starting");
    }   

}

This is my Main class

    AbstractApplicationContext abstractAppContext = new ClassPathXmlApplicationContext("spring-config.xml");
    MessagesBean msgBean2 = abstractAppContext.getBean("msgBean", MessagesBean.class);

This is my output

    Printing Hello World
    Step 2.Bean is starting
    Inside Engine constructor
    Inside Car constructor
    heating up engine

My question is I called only MessageBean in my main class and it's supposed to call only MessageBean Constructor and init method but why two other beans constructors and init method are called or did I do something wrong? What if I have different init, destroy methods for different beans and I only want to initialize/call specific bean(s) constructors and init methods ?

Upvotes: 0

Views: 1287

Answers (1)

Jigar Joshi
Jigar Joshi

Reputation: 240898

by default spring beans gets eagerly initialized, if you want them to initialize lazily add this property in bean definition 

lazy-init="true"

Upvotes: 2

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