Introduction

• In Java, when we provide data like 101, Deepak, 91.4, etc., we need to specify that which type of data we are providing.
• For example, we need to specify that 101 is of type int, Deepak is of type String, and 91.4 is of type float or double.
• So, we can say that in Java, every piece of data has a specific type, known as a "data type".

• Purpose of Data Types :
  • Data types inform the compiler about the kind of data to be stored in a variable.
    For example: Declaring int rollno = 101; tells the compiler that rollno will store an integer.
  • They help allocate the necessary memory for that data, ensuring that the program uses memory efficiently and that data is stored and processed correctly.
    For example: int rollno allocates 4 bytes of memory, same float marks will also store 4 bytes of memory.
  
  
• Data Types & Variables :
  • Data is stored in variables, and each variable is assigned a specific data type.
  • A variable's data type determines what kind of value it can hold and what operations can be performed on it.
  • For example :

    int rollno = 101;
    // "int" is "data type"
    // "rollno" is "variable"
    // "101" is "literal' or "data" (value assigned to the variable)

  
  
• Diagram :
  
  

Types of Data Types

• There are 2 types of Data Types in Java which are as below :-
  1. Primitive Data Types
  2. Non - Primitive Data Types

• Below is the diagram representing the data types in java....

1. Primitive Data Types

• Primitive data types are pre-defined data types.
• There are total 8 primitive data types in Java i.e. boolean, char, byte, short, int, long, float and double.
• Primitive data types have fixed memory sizes for example char always occupies 2 byte of memory, int occupies 4 byte of memory etc.
• Click here to read primitive data types more deeply.

2. Non-Primitive Data Types

• Non-Primitive data types are user-defined or derived data types.
• Non-Primitive data types examples are Strings, Arrays, classes, interfaces etc.
• Non-Primitive data types does'nt have fixed memory sizes, they depends on the data or objects they reference.
  For example, a String object’s memory usage depends on the string's length.
• Click here to read non-primitive data types more deeply.