NullPointerException at Temp. NullPointerException Description The server encountered an unexpected condition that prevented it from fulfilling the request. Exception org. NestedServletException: Request processing failed; nested exception is java. NullPointerException org. NullPointerException com. NullPointerException System. Prev java. NoSuchMethodError Example. Next Core Java Quiz. Pankaj I love Open Source technologies and writing about my experience about them is my passion. Follow Author.
Comments Nafees Kausar says:. An easy fix for this is to add a null check on str1 as shown below:. This will ensure that, when str1 is null , you do not run the length function on it. The idea is that, when you expect a value to be null , its better to put a null check on that variable.
And if the value does turn out to be null , take an alternative action. Here we have a function that accepts three arguments: str1 , strList , and str2. If any of these values turn out to be null , we do not want to execute the logic in this function at all.
This is where Lombok comes handy. In order to add the Lombok library in your code, include the following Maven dependency:. To learn more about Maven, check out this article. Also when we call this function, we put a try-catch block around the function call to catch NullPointerException.
If any of the arguments given in the function turn out to be null , the function would throw a NullPointerException. This would then be caught by the try-catch block. If you run the above snippet, it will work just fine.
Get matched to a bootcamp today. The average bootcamp grad spent less than six months in career transition, from starting a bootcamp to finding their first job. As you can see, we did not initialize an instance of the StringBuilder class while declaring it. When the sb. This is where a NullPointerException gets thrown. Due to the exception being thrown, the JVM cannot execute any statements after this.
Creating a Null Pointer Exception is easy, but avoiding or fixing it is tricky. While some integrated development environments IDEs warn you if you are accessing a variable before initializing it with some compatible value, most IDEs can not figure this out in complex situations, such as when passing a variable through multiple method calls. The exact fix for a Null Pointer Exception depends upon your situation and code.
Here are some of the top ways to fix common Null Pointer scenarios:. The biggest reason why Null Pointer Exceptions occur is human error. Make sure the program you have written carries the correct logic that you had initially intended. Also, run your eyes through the source code to check if you have missed out any statements, or misspelled any variables which may have led to some variable not being assigned a value.
Ensure that you have written your code the way your logic directs you to, and you have not missed out on writing any statements, or have not assigned objects to wrong references. As a rule of thumb, check that before any variable is used, it is initialized with an object. If you know the line of code that is causing your NullPointer and believe your logic is correct as well, you can wrap the section of code in a try-catch block, and define the behavior for when a Null Pointer is caught.
This is how such a set-up will look like:. This happens in situations where a certain reference variable may or may not contain null. More often than not, remote API responses, device interface responses are prone to this scenario.
Depending upon the availability of a result or hardware, the response variable may or may not point to an instantiated object.
Change Language. Related Articles. Table of Contents. Improve Article. Save Article. Like Article. A sample way to create at most one instance of a class is to declare all its constructors as private and then, create a public method that returns the unique instance of the class:.
It throws. Attention reader! Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. Previous Chained Exceptions in Java. Recommended Articles.
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