How do I get around NullPointerException?
If you have spent some time developing programs in Java, at some point you have definitely seen the following exception: Some major production issues arise due to Consider the following piece of code: If you run this code as is, you will get the following exception: The reason you are getting this error
is because we are trying to perform the An easy fix for this is to add a null check on This will ensure that, when But you may have the following question. In
that case you can try something like this:
The idea is that, when you expect a value to be This is applicable not only to strings, but to any other object in Java. Lombok Null CheckNow take the following example:
Here we have a function that accepts three arguments: If any of these values turn out to be How do you achieve this?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. Here's what the code
would look like with the Lombok
Before every argument of the function we add Also when we call this function, we put a If any of the arguments given in the function turn out to be This ensures that, if any of the function arguments turn out to be This can be done with a bunch of Lists and NullsSay that you have a list and you want to print all elements in the list:
Before looping over the list, we need to put a If the
Maps and NullsLet's take the scenario where you need to access the value for a particular key in a map:
First we need to do a null check on the map object itself. If this is not done, and the map is Once that is done, check if a particular key is present before accessing it. You can
check the presence of the key using Is it necessary to always add a Null Check?If you know for certain that a particular variable can never be But if you are not really
certain about the nullability of an object, it is best to add a CodeAll the code discussed in this article can be found in this Github repo. Congrats ?You now know how handle About the authorI love technology and follow advancements in the field. I also like helping others with my knowledge of tech. Feel free to read more of my articles on my blog, connect with me on LinkedIn, or follow me on Twitter. Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started How do I overcome NullPointerException?How to avoid the NullPointerException? To avoid the NullPointerException, we must ensure that all the objects are initialized properly, before you use them. When we declare a reference variable, we must verify that object is not null, before we request a method or a field from the objects.
What causes NullPointerException?What Causes NullPointerException. The NullPointerException occurs due to a situation in application code where an uninitialized object is attempted to be accessed or modified. Essentially, this means the object reference does not point anywhere and has a null value.
How do you fix a NullPointerException in Java?NullPointerException is thrown when a reference variable is accessed (or de-referenced) and is not pointing to any object. This error can be resolved by using a try-catch block or an if-else condition to check if a reference variable is null before dereferencing it.
Can we catch NullPointerException?It is generally a bad practice to catch NullPointerException. Programmers typically catch NullPointerException under three circumstances: The program contains a null pointer dereference. Catching the resulting exception was easier than fixing the underlying problem.
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