In Java, data types are used to define the type and size of values that can be stored in variables. Java's data types can be broadly categorized into two groups: primitive data types and reference data types.

1. Primitive Data Types: These data types represent simple values and are not objects. There are eight primitive data types in Java:

   • byte: 8-bit signed integer, ranges from -128 to 127.
   • short: 16-bit signed integer, ranges from -32,768 to 32,767.
   • int: 32-bit signed integer, ranges from -2^31 to 2^31 - 1.
   • long: 64-bit signed integer, ranges from -2^63 to 2^63 - 1.
   • float: 32-bit floating-point, suitable for decimal values.
   • double: 64-bit floating-point, suitable for precise decimal values.
   • char: 16-bit Unicode character, representing a single character.
   • boolean: Represents true or false values.

2. Reference Data Types: These data types refer to objects and are created using class constructors. They don't hold the actual data but rather store the memory address of the object. Some common reference data types include:

   • String: Represents a sequence of characters.
   • Array: A collection of elements of the same type.
   • Object: The superclass of all other classes in Java.

In addition to these, Java allows developers to create their own custom data types using classes and interfaces, making it a versatile and flexible language.

Remember that each data type has its own memory requirements and range of values it can store. It's essential to choose the appropriate data type based on the nature of the data and the expected range of values to ensure optimal memory usage and program performance. If you want to learn Java data types then choose the best Java training institute in Meerut, Lucknow, Indore, Gwalior and other cities in India.