In the 32-bit version, the representable range is calculated by considering a sign bit, a 23-bit mantissa, and an 8-bit exponent with values between -126 and 127.
Furthermore, the standard provides for the representation of two values for zero (from right to left) two for infinity (positive and negative), and NaN (not a number) values to be used, for example, as results of impossible operations (e.g., divisions by zero).
| Type | Memory Quantity | Represented Information | Default Value |
|---|---|---|---|
| byte | 8 bit | Variable with sign (with "two's complement" representation, two's complement) and represents values in a range [-128 to 127] (inclusive) | 0 |
| short | 16 bit | Signed integers in a range [-32,768, 32,767] | 0 |
| int | 32 bit | Integers (by default signed, signed) in a range [-231, 231-1]. With Java 8, the possibility of using integers to represent unsigned quantities was introduced, which can have a range [0, 232-1] (thanks to specific static methods introduced in the Integer and Long classes) | 0 |
| long | 64 bit | Integers (by default signed, signed) in a range [-263, 263-1]. As with integers in Java 8, there is the possibility of using them as unsigned quantities with a range (positive) that reaches up to 264-1. | 0L |
| float | 32 bit | Single-precision floating-point numbers according to the IEEE 754 specification, using sign, mantissa, and exponent representation.(-1)sign * mantissa * 2exponent | 0.0f |
| double | 64 bit | Double-precision floating-point numbers according to the IEEE 754 specification. The precision with which numbers are represented increases due to the increase in the number of bits used. | 0.0d |
| boolean | not specified, but a single bit would be sufficient | serves to represent only 2 values: true or false (true or false). | false |
| char | 16 bit | Used for storing characters from the Unicode character set) in the range [' ', ''] (in hexadecimal) or equivalently [0,65535]. | |
Exercise
/* I declare three types of variables to test their operation
*
* I perform the following exercise in the second instance to test the operation
* of the while loop
*
* a) I print the numbers from 1 to 10 and
* b) I print the numbers from 1 to 20 and when I reach 20, I continue printing in a
* decreasing manner from 20 to 1
* c) I print the odd numbers between 1 and 100
* d) I print the numbers from 1 to 100, highlighting the multiples of 25
* e) I print the numbers from 1 to 100 in a consecutive manner on a single line, highlighting the
* multiples of 100
* f) I print the numbers from 100 to 1, highlighting the multiples of 7
*
*
*/
public static void main(String[] args) {
// byte handles numbers from -128 to +127
// int char
byte a;
a=-128;
//System.out.println(a);
// we have tested that the number handled by byte
// ranges from -128 to +127
int b;
b=+2147483647;
// System.out.println(b);
char c;
c='@';
int contatore=0;
while(contatore<=1000)
{
System.out.print(contatore + " ");
System.out.print(c);
contatore++;
}
}
Online resources on the topic:
http://www.di-srv.unisa.it/professori/masucci/LPII-0405/slides/Lez03.pdf