request.getSession().getAttribute("cartList")怎么转成HashMap类型的呢,我用 HashMap hMap = (HashMap)request.getSession().getAttribute("cartList");然后用hMap.size()计算大小,出现类型转换异常了,各位高手帮帮忙,谢谢了异常信息如下
java.lang.ClassCastException: java.util.HashMap$Values cannot be cast to java.util.HashMap
at org.apache.jsp.lookshopcart_jsp._jspService(lookshopcart_jsp.java:113)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
java.lang.ClassCastException: java.util.HashMap$Values cannot be cast to java.util.HashMap
at org.apache.jsp.lookshopcart_jsp._jspService(lookshopcart_jsp.java:113)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
可以转成AbstractCollection或者Collection来用,或者你就直接存map对象
java.lang.ClassCastException: java.util.HashMap$Values cannot be cast to java.util.HashMap
这个request.getSession().getAttribute("cartList");不是hashmap类型吧,是map的value?