In this post, we are going to talk about the NullPointerException in Java. We will discuss the main causes and solution to it. I will also discuss how to track down a NullPointerException in Android Studio. I will try to explain at a high level (no low-level explanations) so it can be easily understood.

What causes a NullPointerException?
A NullPointerException is usually thrown when you try to access a field or a method in a variable or an object that is null. This is simple to understand however, it might be a bit confusing for some programmers.

Now, the next question is:
What causes an object to be null?

When you create a variable or an object without instantiating it, then the value of that variable or object is null. So for example, when you have the following code:

String firstName;

The value of firstName in this case would be null.

Now if you try to call a method on the variable firstName, then the NullPointerException will be thrown.

For example:
String firstName;
firstName.toLowerCase();

The above code will throw a null pointer exception on line 2.
Similarly, if you create an object without equating the object, the ugly null pointer exception will be thrown.

For example:
Game newGame;
newGame.start();

The above code will throw the NullPointerException.

How to solve the NullPointerException.
To solve the NullPointerException, you simply need to assign a value to the variable involved. If it is an object, you need to instantiate that object with the new keyword.

Read more: https://fincoapps.com/6-tips-to-becoming-a-better-software-developer/