Nullpointerexception while setting a bean

Question

I have an action URL after clicking a hyper link like so

/SocialStupendous/GetProfile.action?slno=3&slno=3

In my execute method of ActionClass I have the following code

public String execute() {
  int urislno=Integer.parseInt(getServletRequest().getParameter("slno"));
  System.out.println(urislno);
  bean.setUslno(urislno);       
}

I am getting NullPointerException when I am performing bean.setuslno(urislno). Even though urislno is printed properly as 3.

ProfileBean class:

public class ProfileBean {

  private int uslno;

  public int getUslno() {
    return uslno;
  }

  public void setUslno(int uslno) {
    this.uslno = uslno;
  }
}

Why is this happening?

Why are you accessing the parameter directly from the request in the first place? With regards to the NPE, shouldn't it be obvious what's wrong after seeing what's null? — Dave Newton, Jul 06 '13 at 13:05
i want to get hold of those users whomsoever has clicked the url saying getprofile.action .The only way to catch the user was via his/hers slno. Hence i wanted to test if i am able to access the parameters from url which changes corresponding to users — Ravi dunce, Jul 18 '13 at 13:25
There is no need to access the request directly, use av action property. — Dave Newton, Jul 18 '13 at 13:33
Can you kindly brief me up on the av action , i dont know this as am new to struts — Ravi dunce, Jul 18 '13 at 18:22

Roman C · Accepted Answer · 2013-07-05T13:02:01.510

The bean is not initialized. You should initialize it somehow in the action

private ProfileBean bean = new ProfileBean(); 
//and add getter ans setter

the better approach, however is let the container to do it for you. You just need to create a bean configuration in the struts.xml

<bean class="com.yourpackagename.ProfileBean" scope="default"/>

then you would have

private ProfileBean bean;

@Inject
public void setProfileBean(ProfileBean bean) {
  this.bean = bean;
}

and you don't need to parse request for parameters, this is already done by the params interceptor which is a part of defaultStack that your action should run. You should create properties in your action to hold parameter values.

private Integer slno;

public Integer getSlno() {
    return slno;
}

public void setSlno(Integer uslno) {
    this.slno = slno;
}

and the action will look like

public String execute() {

   if (slno != null) {
     System.out.println(slno)
     bean.setUslno(slno);
   }

   ......
   return SUCCESS;
}

= I am new to this kindly tell me how to answer it as accepted — Ravi dunce, Jul 18 '13 at 18:20

Nullpointerexception while setting a bean

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