用如下代码段从数据库中提取数据,初始化下拉列表
<%
String sql3 = "select distinct substr(cyjxh,5,2) as b from ys_dgb01";
ResultSet rs3 = DBbean.exeQuery(sql3);
if(rs3==null){out.println("<script>alert('没有数据!');window.location.href='DBtest.jsp'; </script>");}
rs3.last();
x = rs3.getRow();
rs3.beforeFirst();
while(rs3.next()){
String temxh = rs3.getString(1).trim(); //此行为报错中的57行
if("8-".equals(temxh)){
xh = "8型";}else if("10".equals(temxh)){
xh = "10型";}else if("12".equals(temxh)){
xh = "12型";}else if("14".equals(temxh)){
xh = "14型";}else{
xh = temxh;}
%>
<option value="<%=temxh%>"><%=xh%></option>
<%}%>
</select>
报错如下:(注:通过打印数据集的记录数量得知数据集是有数据的。)
将rs3.getString(1).trim();换成字符串常量就能通过编译,初学,看不懂报错的意思,急盼高手们指点!
org.apache.jasper.JasperException: Exception in JSP: /DBtest/DBtest.jsp:5754: x = rs3.getRow();
55: rs3.beforeFirst();
56: while(rs3.next()){
57: String temxh = rs3.getString(1).trim();
58: if("8-".equals(temxh)){
59: xh = "8型";}else if("10".equals(temxh)){
60: xh = "10型";}else if("12".equals(temxh)){
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause java.lang.NullPointerException
org.apache.jsp.DBtest.DBtest_jsp._jspService(DBtest_jsp.java:120)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
<%
String sql3 = "select distinct substr(cyjxh,5,2) as b from ys_dgb01";
ResultSet rs3 = DBbean.exeQuery(sql3);
if(rs3==null){out.println("<script>alert('没有数据!');window.location.href='DBtest.jsp'; </script>");}
rs3.last();
x = rs3.getRow();
rs3.beforeFirst();
while(rs3.next()){
String temxh = rs3.getString(1).trim(); //此行为报错中的57行
if("8-".equals(temxh)){
xh = "8型";}else if("10".equals(temxh)){
xh = "10型";}else if("12".equals(temxh)){
xh = "12型";}else if("14".equals(temxh)){
xh = "14型";}else{
xh = temxh;}
%>
<option value="<%=temxh%>"><%=xh%></option>
<%}%>
</select>
报错如下:(注:通过打印数据集的记录数量得知数据集是有数据的。)
将rs3.getString(1).trim();换成字符串常量就能通过编译,初学,看不懂报错的意思,急盼高手们指点!
org.apache.jasper.JasperException: Exception in JSP: /DBtest/DBtest.jsp:5754: x = rs3.getRow();
55: rs3.beforeFirst();
56: while(rs3.next()){
57: String temxh = rs3.getString(1).trim();
58: if("8-".equals(temxh)){
59: xh = "8型";}else if("10".equals(temxh)){
60: xh = "10型";}else if("12".equals(temxh)){
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause java.lang.NullPointerException
org.apache.jsp.DBtest.DBtest_jsp._jspService(DBtest_jsp.java:120)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
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空指针...你打印 rs3.getString(1) 自己看...
String temxh = rs3.getString(1).trim(); 改为
String temxh1 = rs3.getString(1);
String temxh = temxh1.trim();
试试
第一个字段的数据中有带特殊符号的,如“-”。
是不是带特殊符号的字段不能用trim()函数啊?