JSF ViewScope beans incorrect hashcode implementation?

Question

I am developing a simple application on JSF having the following dependences

    <dependency>
      <groupId>org.apache.myfaces.core</groupId>
      <artifactId>myfaces-impl</artifactId>
      <version>2.0.2</version>
    </dependency>
   <dependency>
      <groupId>org.apache.myfaces.core</groupId>
      <artifactId>myfaces-api</artifactId>
      <version>2.0.2</version>
    </dependency>

and being a simple page with it backing bean.

xhtml

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml"
          xmlns:h="http://java.sun.com/jsf/html"
          xmlns:f="http://java.sun.com/jsf/core">
        <head>
            <title></title>
        </head>
        <body >

        <h:form>
            <f:view >
                <h:commandButton id="otxMainPanelTextBt" value="click" 
                                 action="#{otherController.doSome}"/>
            </f:view>
        </h:form>

    </body>
    </html>

Java code

import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;


@ManagedBean(name = "otherController")
@ViewScoped
public class Other implements Serializable {

    private static final long serialVersionUID = -6493758917750576706L;

    public String doSome() {
        System.out.println(this);
        return "";
    }
}

If I click on the commandButton many times according to toString source code it should write

class name+hashCode

but it writes something like the following

de.controller.Other@118ea91
de.controller.Other@1e8f930
de.controller.Other@1a38f3c

So, everytime we click there is a different hashcode for the viewscoped bean. Is this incorrect? I have tryed with session beans and this doesn't happen.

EDIT

I modified the class following @BalusC suggestion in the following way.

import java.io.Serializable;

import javax.annotation.PostConstruct;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;


@ManagedBean(name = "otherController")
@ViewScoped
public class Other implements Serializable {

    private static final long serialVersionUID = -6493758917750576706L;

    @PostConstruct
    public void init()
    {
         System.out.println("Post Construction");
    }

    public Other()
    {
         System.out.println("Constructor");
    }

    public void doSome() {
        System.out.println(this);
    }
}

And I found this output after clicking many times.

Constructor
Post Construction
de.controller.Other@b748dd
de.controller.Other@1620dca
de.controller.Other@116358
de.controller.Other@73cb2d
de.controller.Other@1cc3ba0

So, the constructor and PostConstructor Methods are invoked only once, and in spite of this the object still has a different hashcode in every call. This is weird because the constructor with no parameter is supposed to be called on a managed bean instantiation, but it is not, so i still don't understand how can be the object created several times?

Use an updated version of myfaces core. The latest versions (2.0.20, 2.1.14) are considered the most stable. It looks like an ancient issue that was solved in the prehistoric age. — lu4242

BalusC BalusC · Accepted Answer · 2014-02-18T20:10:20

When you return non-null from an action method, a new view is created.

If you want to keep the current view alive, just return null or void from the action method.

E.g.

public void doSome() {
    System.out.println(this);
}

JSF ViewScope beans incorrect hashcode implementation?

1 Answers

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