java HTTP状态500处理JSP页面/FinancialAssessment时发生异常。第440行的jsp

Question

下面是确切的错误

类型异常报告：

message An exception occurred processing JSP page /FinancialAssessment.jsp at line 440

说明：

The server encountered an internal error that prevented it from fulfilling this request.

例外情况：

org.apache.jasper.JasperException: An exception occurred processing JSP page /FinancialAssessment.jsp at line 440

437:                
438:                    
439:                
440:                

    if(std.prev_treatment_start_date.equals("null"))
    441:                {
    442:                    System.out.println("out by krishna------------");

443:                    

堆栈跟踪：

org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

根本原因：

java.lang.NullPointerException
    org.apache.jsp.FinancialAssessment_jsp._jspService(FinancialAssessment_jsp.java:542)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

Answer 1

如果您的错误行是if语句中最常见的错误行，请尝试以下操作：

if( std == null || std.prev_treatment_start_date == null ) {
    .....

这是因为在java中，您必须测试每个对象以避免NullPointerException，这意味着对象为null，不能有方法或属性

Answer 2

std或std.prev_treatment_start_date为空。你应使用：

if (std == null || std.prev_treatment_start_date == null) {

您编写它的方式意味着“std.prev_treatment_start_date是一个字符串，有一个值，这个值等于字符串null”