Struts2-requested list key 'state' could not be resolved as a collection/array/map/enumeration/

Please help me in Struts2, I am stucked in action....

The problem is that I have a application form for accessing that form you should be registered in the database. So the login utility will check for the password & email in the database if it is there than it will go to the app. form otherwise it will throw an error. It is working fine until I want a dropdown in the form say that contains all the States and Cities of India. I want this thing to retrieve from the database but initially I am checking by hardcoding whether its working or not.

So, my Action contains 2 method one is default execute() method which is populating the States of India but the problem is that in the struts.xml file when I am not stating any method than it is executing the default execute method and populating the dropdown but the validation method is not executing and when I am passing the validating method than it is not populating the dropdown. I am sending my codes please help where I am wrong, its very urgent yaar.

I tried redirection also by Message-Store-Interceptor also but that is also not working when I tried to write the states addition list separately in a class file.

Struts.xml

tiles.xml

ApplyAction.java

package net.Candidate.application;

import java.io.*;
import java.sql.*;
import java.util.*;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ActionContext;

import net.database.*;
import net.Candidate.application.model.Apply;
import net.Candidate.application.State;

public class ApplyAction extends ActionSupport {
	
	private Apply apply;
	private List state;
	
	public String execute() throws Exception{
		System.out.println(state);
		  state = new ArrayList();
		  state.add("Maharashtra");
		  state.add("Kerala");
		  state.add("Karnataka");
		  state.add("TamilNadu");
		  return SUCCESS;
		  }
	
	public List getState(){
		return state;	
		}
	
	
	public String applyinterface() {
		try 
		{
			Connection connect = null;
			ResultSet result = null;
			PreparedStatement pstmt = null;
			
			DBConnection getConnect = new DBConnection();
			connect = getConnect.getCon();
			
			int id=0;
			String qry = "SELECT id FROM Register WHERE AppEmail=? && RegPasswd=?";
			pstmt = connect.prepareStatement(qry);
			pstmt.setString(1, apply.getEmail());
			pstmt.setString(2, apply.getPassword());
			result = pstmt.executeQuery();
			while(result.next())
			{
				id = result.getInt(1);
			}
			System.out.println(id);
			boolean comparing = (id == 0); 
			
			if (comparing == true)
			{			
				addActionError(getText("validate_notRegistered"));
		        return ERROR;
			}
			
			else
			{
			return SUCCESS;	
			}
				  
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return SUCCESS;
	}

public Apply getApply() {
		return apply;
	}	
	public void setApply(Apply apply) {
		this.apply = apply;
	}	
}

Apply.java
package net.Candidate.application.model;

import com.opensymphony.xwork2.ActionSupport;

public class Apply extends ActionSupport{
	
	private String password;
	private String email;

public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	 public Apply()
	    {
	    }
}

JSP File

I am also trying like this......
ApplyAction.java

package net.Candidate.application;

import java.io.*;
import java.sql.*;
import java.util.*;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ActionContext;

import net.database.*;
import net.Candidate.application.model.Apply;
import net.Candidate.application.State;

public class ApplyAction extends ActionSupport {
	
	private Apply apply;
	
	public String applyinterface() {
		try 
		{
			Connection connect = null;
			ResultSet result = null;
			PreparedStatement pstmt = null;
			
			DBConnection getConnect = new DBConnection();
			connect = getConnect.getCon();
			
			int id=0;
			String qry = "SELECT id FROM Register WHERE AppEmail=? && RegPasswd=?";
			pstmt = connect.prepareStatement(qry);
			pstmt.setString(1, apply.getEmail());
			pstmt.setString(2, apply.getPassword());
			result = pstmt.executeQuery();
			while(result.next())
			{
				id = result.getInt(1);
			}
			System.out.println(id);
			boolean comparing = (id == 0); 
			
			if (comparing == true)
			{			
				addActionError(getText("validate_notRegistered"));
		        return ERROR;
			}
			
			else
			{	
				//return SUCCESS; <sx:head parseContent="true"/>
				
				int StateID = 0;
				String State = "";
				ResultSet result_state = null;
				
				String Stateqry = "Select * from state";
				pstmt = connect.prepareStatement(Stateqry);
				result_state = pstmt.executeQuery();
				{
				        while (result_state.next())
				        {
				            StateID = result_state.getInt(1);    
				        	State = result_state.getString(2);
				        	System.out.println(State);
				        }
				 } 
			}
				  
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return SUCCESS;
	}

public Apply getApply() {
		return apply;
	}	
	public void setApply(Apply apply) {
		this.apply = apply;
	}	
}

So, how can I pass the value of State & StateID in the jsp <s:select> tag's list, I tried many options but neither of them working, Please help..........