substring（0,9）给我空指针异常 [英] substring(0,9) giving me null pointer exception
问题描述
嗨朋友们，
好像虽然这个空指针不会让我安静地回家!!!!
i有一个jsp页面，我做一个get属性就像这--->
[HTML]<％String s24 =（String）request.getAttribute（" s24"）; ％> [/ HTML]
并且要检索值我做这样的事情--->
[HTML]<％= s24.substring（ 0,9）％> [/ HTML]
但是方法substring（0,9）给了我一个空指针异常。我可以避免或者更确切地消除这种异常/错误吗？请指导我这个:)。
问候，
ajos
hi friends,
seems as if though this null pointers wont let me go peacefully home!!!!
i have a jsp page where i do a get attribute like this--->
[HTML]<%String s24=(String) request.getAttribute("s24"); %>[/HTML]
and to retrieve the value i do some thing like this--->
[HTML]<%=s24.substring(0,9) %>[/HTML]
but the method substring(0,9) is giving me a null pointer exception. have can i avoid or rather eliminate this exception/error?? please guide me regarding this:).
regards,
ajos
推荐答案
嗨朋友们，
好像虽然这个空指针不会让我安静地回家!!!!
i有一个jsp页面，我做了一个得到这样的属性--->
[HTML]<％String s24 =（String）request.getAttribute（" s24"）; ％> [/ HTML]
并且要检索值我做这样的事情--->
[HTML]<％= s24.substring（ 0,9）％> [/ HTML]
但是方法substring（0,9）给了我一个空指针异常。我可以避免或者更确切地消除这种异常/错误吗？请指导我这个:)。
问候，
ajos
hi friends,
seems as if though this null pointers wont let me go peacefully home!!!!
i have a jsp page where i do a get attribute like this--->
[HTML]<%String s24=(String) request.getAttribute("s24"); %>[/HTML]
and to retrieve the value i do some thing like this--->
[HTML]<%=s24.substring(0,9) %>[/HTML]
but the method substring(0,9) is giving me a null pointer exception. have can i avoid or rather eliminate this exception/error?? please guide me regarding this:).
regards,
ajos
字符串s24为空。这意味着名为s24的属性从未传递给JSP。它应该来自哪里？ servlet？
The string s24 is null. That means the attribute called s24 was never passed to the JSP. Where is it supposed to come from? A servlet?
字符串s24为空。这意味着名为s24的属性从未传递给JSP。它应该来自哪里？一个servlet？
The string s24 is null. That means the attribute called s24 was never passed to the JSP. Where is it supposed to come from? A servlet?
hi r035198x，
感谢你的回复。我做的就是在我的servlet --->
hi r035198x,
thanks for your reply yet again.wat i did was in my servlet--->
hi r035198x，
感谢您的回复还有。我做的是我的servlet --->
hi r035198x,
thanks for your reply yet again.wat i did was in my servlet--->
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