Why do you need to use static variables in Java?

Static variables in Java are used when we want to create a variable that is common to all objects of a class, rather than having a separate instance of the variable for each object. This is useful in situations where we need to keep track of information that applies to a class as a whole, rather than to individual objects.

Some common use cases for static variables include:

1. Counter to keep track of the number of instances of a class that have been created.
2. To store a constant value that is common to all objects of a class.
3. To store configuration information that is common to all objects of a class.