Java - Tips - 01

How do you determine the size of primitive data types in JAVA?

• sizeof() operator in C is used to determine the size of its operand (memory (RAM) required) 
• In JAVA, there is no sizeof() operator as in C

Wrapper classes: 

• It provides a way to use primitive data typesas objects 
• Byte, Short, Integer, Long, Float, Double, Character and Boolean are the wrapper classes for the primitive data types byte, short, int, long, float, double, char and boolean respectively
• Except for the Boolean wrapper class, all other classes have SIZE and BYTES attributes
• The SIZE attribute determines the size of the data type in bits whereas, the BYTES returns the size of the datatype in bytes.

Example:

class DetermineSize 

{ 

     public static void main(String args[])

     {

             System.out.println("size of byte (in bits)="+Byte.SIZE+" bits"); 

             System.out.println("size of byte (in bytes)="+Byte.BYTES+" byte"); 

             System.out.println("size of short (in bits)="+Short.SIZE+" bits"); 

             System.out.println("size of short (in bytes)="+Short.BYTES+" bytes"); 

             System.out.println("size of int (in bits)="+Integer.SIZE+" bits");

             System.out.println("size of int (in bytes)="+Integer.BYTES+" bytes");
             System.out.println("size of long (in bits)="+Long.SIZE+" bits");

             System.out.println("size of long (in bytes)="+Long.BYTES+" bytes");

             System.out.println("size of float (in bits)="+Float.SIZE+" bits");

             System.out.println("size of float (in bytes)="+Float.BYTES+" bytes");

             System.out.println("size of double (in bits)="+Double.SIZE+" bits"); 

             System.out.println("size of double (in bytes)="+Double.BYTES+" bytes"); 

             System.out.println("size of char (in bits)="+Character.SIZE+" bits");

             System.out.println("size of char(in bytes)="+Character.BYTES+" bytes");

      }

}

OUTPUT:

size of byte (in bits)=8 bits

size of byte (in bytes)=1 byte

size of short (in bits)=16 bits

size of short (in bytes)=2 bytes

size of int (in bits)=32 bits

size of int (in bytes)=4 bytes

size of long (in bits)=64 bits

size of long (in bytes)=8 bytes

size of float (in bits)=32 bits

size of float (in bytes)=4 bytes

size of double (in bits)=64 bits

size of double (in bytes)=8 bytes

size of char (in bits)=16 bits

size of char(in bytes)=2 bytes