Java – Basic Data Types

Integers

Java defines four integer types: byte, short, int, and long.

Type Width in Bits Range
byte
8
–128 to 127
short
16
–32,768 to 32,767
int
32
–2,147,483,648 to 2,147,483,647
long
64
–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

Java does not support unsigned (positive-only) integers.

Floating-Point Types

Type Width in Bits  Range
double
64
4.9e–324 to 1.8e+308
float
32
1.4e–045 to 3.4e+038

Characters

In Java, characters are not 8-bit quantities like they are in most other computer languages. Instead, Java uses Unicode. Unicode defines a character set that can represent all of the characters found in all human languages. Thus, in Java, char is an unsigned 16-bit type having a range of 0 to 65,536. The standard 8-bit ASCII character set is a subset of Unicode and ranges from 0 to 127. Thus, the ASCII characters are still valid Java characters.

A character variable can be assigned a value by enclosing the character in single quotes. For example, this assigns the variable ch the letter X:

  char ch;
  ch = 'X';

You can output a char value using a println( ) statement. For example, this line outputs the value in ch:

System.out.println("This is ch: " + ch);

In java it is possible to perform arithmetic operations on characters like increment character with + sign. example :

class CharArithmetic {
 public static void main(String args[]) {
 char ch;
 ch = 'X';
 System.out.println("ch contains " + ch);
 ch++; // increment ch
 System.out.println("ch is now " + ch);
 ch = 90; // give ch the value Z
 System.out.println("ch is now " + ch);
 }
}

Booleans

The boolean type represents true/false values. Java defines the values true and false using the reserved words true and false. Thus, a variable or expression of type boolean will be one of these two values.

class BooleanCheck {
public static void main(String args[]) {
 boolean b1;
 b1 = false;
 System.out.println("b is " + b1);
 b1 = true;
 System.out.println("b is " + b1);
 // a boolean value can control the if statement, because if(true or
 // false) is evaluation for if condition which was o and 1 in c and c++
 if (b1)
 System.out.println("b1 is true");
 b1 = false;
 if (b1)
 System.out.println("b1 is false, will not executed");
}
}