JDEP 183H

Handout 2: Numerical Data

August 24, 2006

Table 2.1 Java numerical data types and their precisions.

Data Type	Content	Default Value*	Minimum Value	Maximum Value
byte	Integer	0	-128	127
short	Integer	0	-32768	32767
int	Integer	0	-2147483648	2147483647
long	Integer	0	-9223372036854775808	9223372036854775807
float	Real	0.0	-3.40282347E+38	3.40282347E+38
double	Real	0.0	-1.79769313486231570E+308	1.79769313486231570E+308

* No default value is assigned to a local variable

Table 2.2 Arithmetic operators.

Operation	Java Operator	Example	Value (x = 10, y = 7, z = 2.5)
Addition	+	x + y	17
Subtraction	-	x - y	3
Multiplication	*	x * y	70
Division	/	x / y x / z	1 4.0
Modulo Division (Remainder)	%	x % y	3

Table 2.3 Precedence rules for arithmetic operators and parentheses.

Order	Group	Operator	Rule
High Low	Subexpression	( )	Subexpressions are evaluated first. If parentheses are nested, the innermost subexpression is evaluated first. If two or more pairs of parentheses are on the same level, then they are evaluated from left to right.
	Unary operator	-, +	Unary minuses and pluses are evaluated second.
	Multiplicative operator	*, /, %	Multiplicative operators are evaluated third. If two or more multiplicative operators are in an expression, then they are evaluated from left to right.
	Additive operator	+, -	Additive operators are evaluated last. If two or more additive operators are in an expression, then they are evaluated from left to right.

Table 2.4 Rules for arithmetic promotion.

Operator Type	Promotion Rule
Unary	if the operand is of type byte or short, then it is converted to int. Otherwise, the operand remains the same type.
Binary	if either operand is of type double, then the other operand is converted to double. Otherwise, if either operand is of type float, then the other operand is converted to float. Otherwise, if either operand is of type long, then the other operand is converted to long. Otherwise, both operands are converted to int.

Table 2.5 Common wrapper classes and their conversion method.

Class	Method	Example
Integer	parseInt	Integer.parseInt(“25”) à 25 Integer.parseInt(“25.3”) à error
Long	parseLong	Long.parseLong(“25”) à 25L Long.parseLong(“25.3”) à error
Float	parseFloat	Float.parseFloat(“25.3”) à 25.3F Float.parseFloat(“ab3”) à error
Double	parseDouble	Double.parseDouble(“25”) à 25.0 Double.parseDouble(“ab3”) à error

Based on (Wu 2004)