setAttribute（String, Object）对于参数（String, int）不适用

类型 ServletContext 中的方法 setAttribute（String, Object）对于参数（String, int）不适用
package com.control;

import javax.servlet.ServletContextEvent;

public class ApplicationListener implements javax.servlet.ServletContextListener{

public void contextDestroyed(ServletContextEvent arg0) {
// TODO 自动生成方法存根

System.out.println("contextDestroyed");
}

// application start
public void contextInitialized(ServletContextEvent arg0) {
// TODO 自动生成方法存根
System.out.println("contextInitialized");

arg0.getServletContext().setAttribute("usernum",0 );

}

}

arg0.getServletContext().setAttribute("usernum",new Integer(0));