References and Primitive Data Types

Two types of entities are identified by JAVA

  • Primitive
  • Objects

Primitive Data Types in JAVA

  • most basic types of data
  • 8 primitive data types
  • They have fixed size
  • They are limited to range of value
  • byte
    • has size of 8 bits
    • minimum value is -128
    • maximum value is +127
    • example : byte c=32;
  • short
    • size of 16 bits
    • minimum value: -2^15
    • maximum value: (2^15)-1
    • example: short s=55;
  • char
    • size of 16 bits
    • minimum value: 0
    • maximum value: (2^16)-1
    • All Unicode characters are char
  • int
    • size: 32 bits
    • minimum value: 0-2^31
    • maximum value: (2^31_-1
    • Example: int i=25;
  • long
    • 64 bits size
    • minimum value: (-2)^31
    • maximum value: (2^31)-1
  • Float
    • Size: 32 bits
    • minimum value: 2^-149
    • maximum value: (2-2^-23)·2^127
  • double
    • 64 bits size
    • +/-10-308 to +/-10+308 and 0, about 15 digits precision
  • boolean
    • True or false

Reference variables

store the address of an object

No notion of “object (physically) in the stack”

No notion of “object (physically) within an object