This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
req.getParameter("doit").equal("good");
Is it impossible to write this line in the
method? Without it, the program runs correctly. However whenever I write that line, it shows the error messages..
java.lang.NullPointerException at adhoc.FinePrint.doFilter(FinePrint.java:50)
Is there any way that I can check whether "doit" parameter is equal to "good"??
I'd recommend to turn your equals around to
"good".equals(req.getParameter("doit"));
This prevents the NullPointerException when the request parameter "doit" is not set.
Related
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 4 years ago.
while successful login reporting a error
actual source code
Quoting the documentation
java.lang.String getParameter(java.lang.String name)
Returns the value of a request parameter as a String, or null if the parameter does not exist
As far as I can see, you don't pass a parameter to your page and therefore getParameter returns null and you try to access it without actually checking it.
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
NullPointerException Error using linked lists
(2 answers)
Closed 6 years ago.
Let's get to the point. I'm using a LinkedList to store some info about the objects it store. The thing is, I can't set all the attributes of the objects right when I create it, so I need to access them later. In fact, this is the piece of code where I access it.
listaNodos.get(esteNodo(nodoActual)).caminoVuelta.getLast().setFin(currentGrid); listaNodos.get(esteNodo(nodoActual)).caminoVuelta.getLast().setPath(caminoVuelta);
Just as a clarification: caminoVuelta is also a LinkedList.
So, can I modify the atributes of the instances stored in caminoVuelta by simply accessing them with getLast() method from LinkedList and then using the set() methods? Or will this change never happen to the original object?
For some reason, (and it only happens for the first node(Nodo) I create) it returns a NullPointerException.
I hope it's clear enough. Thanks.
This question already has answers here:
Converting a generic argument to an int in java, provided that it is a number
(4 answers)
Closed 8 years ago.
I have the next problem:
I am making a simple cast:
TargetBot2Params params = (TargetBot2Params)bot.getParams();
But I get the next error:
Inconvertible types
Requiered: TargetBot2Params
Found: UT2004BotParameters
And I dont know why occurs this, because I think that it doesnt do the cast.
Anyone knows why occurs this?
Thanks for your time.
The error message says it all.
For the casting to be successful, UT2004BotParameters has to either be a TargetBot2Params (i.e., extends TargetBot2Params) or, if TargetBot2Params is an interface, implement it.
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 8 years ago.
I have faced many time the NullPointerException in android. Some times I understand why the exception is thrown.
My Question is: Android applications are developed in Java and Java does not support pointers, then why is the exception called NullPointerException?
NullPointerException is a situation in code where you try to access/ modify an object which has not been initialized yet. It essentially means that object reference variable is not pointing anywhere and refers to nothing or ‘null’.
A NullPointerException is thrown when you use a null reference. The name is a holdover from an early prototype of Java.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Get current stack trace in Java
Here is the thing, i want to get a list of all called methods in a java class. So far i've been using eclemma, but that just insn't enough. I also want the order in which the methods have been called.
You can log each method as it is called (with its arguments if you like). You can add a line to each method or use AOP to do this for you.