Primitive Type

18 Oct 2024 . java .

  • 6 Digital types：
    • byte、short、int、long
    • float、double
  • char
  • boolean
Type Bits Bytes Default Range
byte 8 1 0 -128 ~ 127
short 16 2 0 -32768 ~ 32767
int 32 4 0 -2147483648 ~ 2147483647
long 64 8 0L -9223372036854775808 ~ 9223372036854775807
char 16 2 ‘u0000’ 0 ~ 65535
float 32 4 0f 1.4E-45 ~ 3.4028235E38
double 64 8 0d 4.9E-324 ~ 1.7976931348623157E308
boolean 1   false true、false

Primitive Type VS Packaging Type

  • If the packaging variable is default null, and the primitive variable has a default value (not null).
  • Packaging types can be used for generic, but primitive types cannot.
  • Primitive types take up less space

Packing VS Unpacking

  • Packing: Pack the primitive types with their corresponding packaging types.

    Integer A=Integer.valueOf(1)

  • Unpacking: Convert the packaging type to the primitive type.

    int a = new Integer(1).intValue()