What are the different types of Java variables?

In Java, variables can be divided into different types based on their data type.

1. Basic data types: include integers (byte, short, int, long), floating-point numbers (float, double), characters (char), and booleans (boolean).
2. Data types in Java include class, interfaces, arrays, enums, and strings.
3. Automatic packing and unpacking types include automatic packing wrapper types (Byte, Short, Integer, Long, Float, Double, Character, Boolean).
4. Null type: represents a variable that does not reference any object.

These variable types can be used to store different types of data, each with its own operations and limitations.