How do I overcome Java Lang 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 What causes Java Lang NullPointerException?Some of the common reasons for NullPointerException in java programs are: Invoking a method on an object instance but at runtime the object is null. Accessing variables of an object instance that is null at runtime. Throwing null in the program.
How can we avoid NullPointerException in Java if condition?To avoid NullPointerException in java programming, always make sure that all the objects are properly initialized before you use them. Before invoking a method on an object, verify that the object is not null while declaring a reference variable.
What causes a null pointer?NullPointerException is thrown when program attempts to use an object reference that has the null value. These can be: Invoking a method from a null object. Accessing or modifying a null object's field.
Can we override NullPointerException?Yes, we can override that method which throws NullPointerException in superclass and throws Runtime Exception in subclass.
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