在线等候nullpointExecpion

xuefeifangpei 2003-04-08 12:30:33

我有如下语句在判断是都用了xx!=null进行判断,但是仍然出错究竟时什么原因

tousu_end_date1=request.getParameter("tousu_end_date");
if (tousu_end_date1 ==null)
tousu_end_date1 ="";
depart1=request.getParameter("depart");
if (depart1 ==null)
depart1 ="";
details1=request.getParameter("details");
if (details1 ==null)
details1 ="";
handle1=request.getParameter("handle");
if (handle1 ==null)
handle1 ="";
person1=request.getParameter("person");
if (person1 ==null)
person1 ="";
tousu_class1=request.getParameter("tousu_class");
if (tousu_class1 ==null)
tousu_class1 ="";
strSQL="select * FROM data where ";

if(!tousu_class1.trim().equals(""))
strSQL=strSQL+" and tousu_class like '%"+tousu_class1+"%' ";
if(!depart1.trim().equals("") )
strSQL=strSQL+" depart = '"+depart1+"' ";
if( !handle1.trim().equals("") )
strSQL=strSQL+" and handle = '"+handle1+"' ";
if( !details1.trim().equals("") )
strSQL=strSQL+" and details like '%"+details1+"%' ";
if( !person1.trim().equals("") )
strSQL=strSQL+" and person = '"+person1+"' ";
if(!tousu_start_date1.trim().equals("") && !tousu_end_date1.trim().equals("") )
strSQL=strSQL+" and tousu_date between #"+tousu_start_date1+"# and #"+tousu_end_date1+"# order by tousu_date desc";

...全文

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16 条回复

切换为时间正序

当前发帖距今超过3年，不再开放新的回复

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kreven 2003-04-08

同意调试

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kyouyouCafe 2003-04-08

后半部分好象有问题.
尝试:
String str = tousu_class1;
if(str != null && str.trim().length()>0){
//deal with

}
后面也象前面那样处理...

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flashroom 2003-04-08

用==判断试试

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xuefeifangpei 2003-04-08

谢谢!我这样好了
tousu_start_date1=request.getParameter("tousu_start_date");
if (tousu_start_date1==null)
tousu_start_date1="";
tousu_end_date1=request.getParameter("tousu_end_date");
if (tousu_end_date1 ==null)
tousu_end_date1="";
depart1=request.getParameter("depart");
if (depart1==null)
depart1="";
details1=request.getParameter("details");
if (details1==null)
details1="";
handle1=request.getParameter("handle");
if (handle1==null)
handle1="";
person1=request.getParameter("person");
if (person1==null)
person1="";
tousu_class1=request.getParameter("tousu_class");
if (tousu_class1==null)
tousu_class1="";
strSQL="select * FROM data where ";
if(tousu_class1!=null && tousu_class1.trim().length()>0)
strSQL=strSQL+" tousu_class like '%"+tousu_class1+"%' and ";

if(depart1!=null && depart1.trim().length()>0 )
strSQL=strSQL+" depart = '"+depart1+"' and ";

if(handle1!=null && handle1.trim().length()>0 )
strSQL=strSQL+" handle = '"+handle1+"' and ";

if(details1!=null && details1.trim().length()>0 )
strSQL=strSQL+" details like '%"+details1+"%' and ";

if(person1!=null && person1.trim().length()>0 )
strSQL=strSQL+" person = '"+person1+"' and ";

if(tousu_start_date1!=null && tousu_start_date1.trim().length()>0 && tousu_end_date1!=null && tousu_end_date1.trim().length()>0 )
strSQL=strSQL+" tousu_date between #"+tousu_start_date1+"# and #"+tousu_end_date1+"# order by tousu_date desc";

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nbm0 2003-04-08

请这样；

if(str != null && str.length() > 0)
{
do what you want to do
}

上面语句中，str != null 先判断是否为空，str.length() > 0再判断长度是否为0
都不成立，则str有内容！

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dalyyy 2003-04-08

你先把strSQL print 出来看一下就知道strSQL对不对了，如果strSQL没问题的话就是别的代码的问题了

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dybine 2003-04-08

这段代码没有错，错误可能在你别的代码上

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niko7 2003-04-08

你先用个简单点的页面好好调一下吧。

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kyouyouCafe 2003-04-08

当然了.
你要先确定String 类型的对象不为空.
然后再判断长度是否为零.

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teva 2003-04-08

看异常类型
这样的问题不需要怎么琢磨源码

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kyouyouCafe 2003-04-08

depart1.trim().length()>0 中没加"AND".
下断点调试,看哪儿有错?

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vick 2003-04-08

对空对象进行了操作（比如转换操作等等，string 类型空串的trim();）

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xuefeifangpei 2003-04-08

查depart1能够,但是查其他的就报错不知道什么原因哦??

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xuefeifangpei 2003-04-08

还是报nullpoint错
tousu_start_date1=request.getParameter("tousu_start_date");
if (tousu_start_date1==null)
tousu_start_date1="";
tousu_end_date1=request.getParameter("tousu_end_date");
if (tousu_end_date1 ==null)
tousu_end_date1="";
depart1=request.getParameter("depart");
if (depart1==null)
depart1="";
details1=request.getParameter("details");
if (details1==null)
details1="";
handle1=request.getParameter("handle");
if (handle1==null)
handle1="";
person1=request.getParameter("person");
if (person1==null)
person1="";
tousu_class1=request.getParameter("tousu_class");
if (tousu_class1==null)
tousu_class1="";
strSQL="select * FROM data where ";
if(tousu_class1.trim().length()>0)
strSQL=strSQL+" and tousu_class like '%"+tousu_class1+"%' ";

if(depart1.trim().length()>0 )
strSQL=strSQL+" depart = '"+depart1+"' ";

if(handle1.trim().length()>0 )
strSQL=strSQL+" and handle = '"+handle1+"' ";

if(details1.trim().length()>0 )
strSQL=strSQL+" and details like '%"+details1+"%' ";

if(person1.trim().length()>0 )
strSQL=strSQL+" and person = '"+person1+"' ";

if(tousu_start_date1.trim().length()>0 && tousu_end_date1.trim().length()>0 )
strSQL=strSQL+" and tousu_date between #"+tousu_start_date1+"# and #"+tousu_end_date1+"# order by tousu_date desc";

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kyouyouCafe 2003-04-08

是
tousu_class1.trim().length()>0
不是length.

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xuefeifangpei 2003-04-08

..\work\localhost\tousu\_0002fsql_0005fok_0002ejspsql_0005fok_jsp_84.java:186: Attempt to reference method length in class java.lang.String as an instance variable.
if(tousu_class1.trim().length>0)
类型好像报错啊

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