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