java - Action class value passing one method to another method -

the value not passing method 1 method 2 shows null pointer exception please me this.

in struts2 action class contains 2 methods. 1 method produce value used method. in jsp page have 2 buttons. 1 calls first method populate value. button calls second method in same class , use populated value first method , display values in jsp. every button click action class object destroyed , create new object every button click. first method values lost , can not referred second method. please tell me solution this.

struts2 action class :

 public class crudaction{      private list<string> list;      public list<string> getlist() {          return list;      }     //method 1      public string one(){          list=new arraylist<string>();          list.add("one");         list.add("two");         return "success";      }    //method 2       public string two(){          list.add("three");         return "success";      }  }     

struts.xml :

<action name="one" class="com.crudaction" method="one">   <result name="success">/index.jsp</result> </action> // second method <action name="two" class="com.crudaction" method="two">   <result name="success">/index.jsp</result> </action>  

in jsp :

for first method

<input  type = "button" value = "one" onclick = "javascript:location.href='one.action';"/> 

second method

<input  type = "button" value = "two" onclick"javascript:location.href='two.action';"/> 

considering http protocol stateless object create in first request cannot referenced in second request hence there 2 options.

1 .create hidden input tag contain list id, when request second time, struts 2 method can id (as parameter). expensive create again depends on needs

2 .before render jsp in first request, can put object in session scope using actioncontext. eg

map<string,object> session = actioncontext.getcontext().getsession(); session.put("mylist",list); in second request can access object  map<string,object> session = actioncontext.getcontext().getsession(); list<string> mylist=(list)session.get("mylist");   map<string,object> session = actioncontext.getcontext().getsession(); session.remove("mylist");