Bean of Singleton scope

 

 
When no explicit scope is mentioned during bean definition, it is taken by default as single.

 

Step 1: Define the POJO

 
File : Amount.java

package com.simpleCodeStuffs;

public class Amount {

private String val;

public String getVal() {
return val;
}

public void setVal(String val) {
this.val = val;
}
}

 

Step 2 : Define the bean definition

 
File : Beans.xml
 

Note, only the bean is defined. Property values are injected from the main class in order to provide some clarity on the subject. Also note, the scope has no€™t been mentioned in the bean definition. Therefore, the bean takes the default scope of singleton

 

Step 3

 
Create the Main class to receive the object from the beanId and place the call

File : MainClass.java
 

package com.simpleCodeStuffs;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.simpleCodeStuffs.Amount;

public class MainClass {

public static void main(String[] args) {
ApplicationContext context =  new ClassPathXmlApplicationContext("Beans.xml");
Amount Firstamt=(Amount)context.getBean("amount");
/* instance of bean returned*/

Firstamt.setVal("SimpleCodeStuffs");

System.out.println(Firstamt.getVal());

Amount Secondamt=(Amount)context.getBean("amount");
/*For singleton scope, new bean instance
is not returned at this point. Hence the same value is printed. */

System.out.println(Secondamt.getVal());
}
}

 

Note that, as the bean is of singleton scope, only one instance is returned for the beanID amount€™ per IOC container. This can be seen in the output as the same value is printed twice, once for Firstamt and once for Secondamt.

 

Step 4 : Run the application. The output is