Select Tag Problem

insertSeller.java

package BookRez.Database;

import BookRez.BookInfo.BookBasicInfo;
import com.opensymphony.xwork2.ActionSupport;
import java.util.*;
import java.sql.*;
import java.math.*;

public class insertSeller extends ActionSupport {

private String ISBN = null;
	private String Email = null;
	private String Condition = null;
	private List<String> ConditionList;
	private BigDecimal Price;
	private String Comment = null;
	
	public void setISBN(String ISBN){
		this.ISBN = ISBN;
	}
	
	public String getISBN(){
		return ISBN;
	}
	
	public void setEmail(String Email){
		this.Email = Email;
	}
	
	public String getEmail(){
		return Email;
	}
	
	public String getCondition(){
		return Condition;
	}
	
	public void setCondition(String Condition){
		this.Condition = Condition;
	}
	
	public List<String> getConditionList(){
		return ConditionList;
	}
	
	public void setConditionList(List<String> ConditionList){
		this.ConditionList = ConditionList;
	}
	
	public BigDecimal getPrice(){
		return Price;
	}
	
	public void setPrice(BigDecimal Price){
		this.Price = Price;
	}
	
	public String getComment(){
		return Comment;
	}
	public void setComment(String Comment){
		this.Comment = Comment;
	}
	
	public void SelectCondition(){
		ConditionList = new ArrayList<String>();
		ConditionList.add("Like New");
		ConditionList.add("Very Good");
		ConditionList.add("Good");
		ConditionList.add("Acceptable");
	}
	
	public String execute() throws Exception {
		SelectCondition();
		/*String connection = "jdbc:mysql://localhost:3306/";
		String dbName = "BookSourceDB";
		String driverName = "org.gjt.mm.mysql.Driver";
		String userName = "regUser";
		String password = "regUser";
		Connection con = null;
		Statement stmt= null;
		
		try{
			Class.forName(driverName).newInstance();
			con = DriverManager.getConnection(connection+dbName, userName, password);
			stmt = con.createStatement();
		}
		catch(Exception e){
			System.out.println(e.getMessage());
		}
		*/
		/*
		String inputISBN = getISBN();
		String inputEmail = getEmail();
		String inputCondition = getCondition();
		BigDecimal inputPrice = getPrice();
		String inputComment = getComment();
		*/
		/*
		stmt = con.createStatement();
			int val = stmt.executeUpdate("INSERT into SellerRecord (isbn, email, cond, price, comment) VALUES ('" + inputISBN + "','" + inputEmail + "','" + inputCondition + "','" + inputPrice + "','" + inputComment + "')'");
		
		if(val == 0){
			return ERROR;
		}
		
		else{
		*/
		return SUCCESS;
		//}
	}
}

insertSeller.jsp

error code

Servlet.service() for servlet jsp threw exception
tag 'select', field 'list', name 'Condition': The requested list key 'ConditionList' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
	at org.apache.struts2.components.Component.fieldError(Component.java:231)
	at org.apache.struts2.components.Component.findValue(Component.java:293)
	at org.apache.struts2.components.ListUIBean.evaluateExtraParams(ListUIBean.java:79)
	at org.apache.struts2.components.Select.evaluateExtraParams(Select.java:99)
	at org.apache.struts2.components.UIBean.evaluateParams(UIBean.java:780)
	at org.apache.struts2.components.UIBean.end(UIBean.java:481)
	at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:43)
	at org.apache.jsp.insertSeller_jsp._jspx_meth_s_005fselect_005f0(insertSeller_jsp.java:193)
	at org.apache.jsp.insertSeller_jsp._jspx_meth_s_005fform_005f0(insertSeller_jsp.java:121)
	at org.apache.jsp.insertSeller_jsp._jspService(insertSeller_jsp.java:74)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:386)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:416)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
	at java.lang.Thread.run(Unknown Source)

I've searched all over the place.
lots of ppl seems to having the same problem with no solution.
please help!