What are the data types in Java?

In Java, there are two main types of data: primitive and reference.

Primitive data types store their values directly in memory allocated for the variable.

Type	Size (bits)	Range
byte	8	-128 to 127
short	16	-32,768 to 32,767
int	32	-2³¹ to 2³¹ - 1
long	64	-2⁶³ to 2⁶³ - 1
float	32	Single-precision floating point
double	64	Double-precision floating point
boolean	Not defined	true or false
char	16	Unicode character

Reference data types store references to objects in memory. The objects themselves are stored in the heap.

• Classes: Define the structure and behavior of objects.

  class MyClass {
      // Fields and methods
  }
  

• Interfaces: Define a contract for classes.

  interface MyInterface {
      // Abstract methods
  }
  

• Arrays: Collections of elements of the same type.

  int[] numbers = new int[5];
  String[] names = {"Alice", "Bob"};
  

• Enumerations: Set of named constants.

  enum Day {
      MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
  }
  

• Annotations: Provide metadata about the code.

  @Override
  

• Strings: Are objects of the String class.

  String message = "Hello, World!";