what is null pointer exception

Workaround for use of Getservletcontext () in servlet to get ServletContext object java.lang.NullPointerException (null pointer) exceptionToday encountered a java.lang.NullPointerException (null pointer) exception in the Servlet service method that gets the ServletContext ob

Recently in the use of El expression, the use of the int variable, because, many times, the variable will not be assigned to the initial value, after consideration, should be declared from int to Integer, after the change has been reported null pointer exception, after careful review, my getter and setter method, either set int or return int, which has been teste

Today encountered a java.lang.NullPointerException (null pointer) exception in the Servlet service method that gets the ServletContext object, the code is as follows:// get ServletContext Object this. Getservletcontext ();This is a very strange and first-time encounter, beca

Today encountered a java.lang.NullPointerException (null pointer) exception in the Servlet service method that gets the ServletContext object, the code is as follows:1//Get ServletContext object 2 ServletContext ServletContext = This.getservletcontext ();This is a very stran

Today encountered a java.lang.NullPointerException (null pointer) exception in the Servlet service method that gets the ServletContext object, the code is as followsGets the ServletContext object ServletContext ServletContext = This.getservletcontext ();This is a very strang

1.dataManager when get what thing null pointer, most likely is not initialized, even if the global variable is initialized in another place, here also need to call.2. Error loading pictureThis.mImageLoader.get (Imgurl,listener);All three objects have a value, but a

If you operate on NULL, a null pointer exception is generatedObject obj = new Object ();You know, obj is an object pointer variable that points to an instance of the object classIf this

This article is organized from the Lonely Wolf Big Blog,,,Getting the ServletContext object in the Servlet's service method also java.lang.NullPointerException (null pointer) exception, the code is as follows:gets the ServletContext object this.getservletcontext (); 　It turn

A colleague partially modified the company's development framework based on the latest spring, tomcat, and Java versions. After the development and running, he found a strange NULL pointer exception. To restore the current scenario, the code is roughly as follows. All servlets inherit from baseservlet. Take DefaultServ

Today I see a piece of code in a book like this:This is the code for the BR>Choose the singer you like:inputtype= "checkbox"name= "Singer"value= "Zhang">singer Zhanginputtype= "checkbox"name= "Singer"value= "Lee">Lee singerinputtype= "checkbox"name= "Singer"value= "King">Wang singerThe following is an array implementationString personname[]=request.getparametervalues ("singer");//Gets the name of the singer

In the course of today's project, with JUnit testing, I want to get user on the page end and store user-related information in session, but Servletactioncontext.getrequest (). GetSession (); Get session, always report null pointer exception, do not know where to go wrong, because this servletactioncontext is not our o

Category:2008-06-04 12:47 467 people read reviews (0) Collection report Linuxjava test Yesterday, When a colleague A is testing a program written by colleague B, an error occurs, looking at the console information and discovering that a null pointer exception was thrown.The survey results show that when flag does

Yesterday, the tester submitted to me a bug, in version 2.3, when the pop-up Popupwindow, there will be a null pointer exception, in the high version no problem, the following is the error message (Find the same exception, my exception