Numeric Data Types

1
Numeric Data Types

• There are six numeric data types byte, short,
  int, long, float, and double.
• Sample variable declarations
• int i, j, k
• float numberOne, numberTwo
• long bigInteger
• double bigNumber

2
Data Type Precisions
The six data types differ in the precision of
values they can store in memory.
3
Primitive Data Declaration and Assignments
int firstNumber, secondNumber firstNumber
234 secondNumber 87
State of Memory
Code
4
Assigning Numeric Data
int number number 237 number 35
int number number 237 number 35
State of Memory
Code
5
Numeric Data Types

• At the time a variable is declared, it also can
  be initialized. For example, we may initialize
  the integer variables count and height to 10 and
  34 as
• int count 10, height 34
• Ping out to reality NumericVariables.java

6
Numeric Literal Values

• Integer types can be
• Positive or negative
• Decimal, e.g., -5653
• Octal, e.g., 05653 (but not 09876)
• Hexidecimal, e.g., 0x5A1
• Long, e.g., 14084591234L
• Real types can be
• Float, e.g., 1.23f
• Double, e.g., -2.34
• Scientific, e.g., 2.17e-27f or -456.2345e19

7
Arithmetic Operators

• The following table summarizes the arithmetic
  operators available in Java.
• and -- for integer type variables

8
Arithmetic Expressions

• Examples
• sum firstNumber secondNumber avg (one
  two three) / 3.0
• total
• Assignment operators
• Tral-la-la, out to reality NumericOperators.java

9
Arithmetic Expressions

• How does the expression
• x 3 y
• get evaluated? Answer x is added to 3y.
• We determine the order of evaluation by following
  the precedence rules.
• A higher precedence operator is evaluated before
  the lower one. If two operators are the same
  precedence, then they are evaluated left to right
  for most operators.

10
Precedence Rules
11
Example

• a (b -(c / d) / e) (f - g h)
• a -b - (d e f) (-g h)
• a 10
• b 5
• c 23
• d 4
• e 2
• f 5
• g 8
• h 3

12
Example Program

• Flonk out to reality NumericPrecedence.java

13
Type Casting

• If x is a float and y is an int, what will be the
  data type of the following expression?
• x y
• The answer is float.
• The above expression is called a mixed
  expression.
• The data types of the operands in mixed
  expressions are converted based on the promotion
  rules. The promotion rules ensure that the data
  type of the expression will be the same as the
  data type of an operand whose type has the
  highest precision.

14
Promotion Rules
15
Assignment Conversion

• If a lower precision value is assigned to a
  higher precision variable, type casting occurs
• Example
• double number
• number 25
• is legal but
• int number
• number 23.45
• is not

16
Explicit Type Casting

• Instead of relying on the promotion rules, we can
  make an explicit type cast by prefixing the
  operand with the data type using the following
  syntax
• ( ltdata typegt ) ltexpressiongt
• Example
• (float) x / 3
• (int) (x / y 3.0)

17
Example Program

• Fuuuurtang out to reality NumericCasting.java

18
Constants

• We can change the value of a variable. If we want
  the value to remain the same, we use a constant.
• final double PI 3.14159 final
  int MONTH_IN_YEAR 12 final short
  FARADAY_CONSTANT 23060

19
Use of Constants

• Very often class variables that are initialized
• May be private or public
• Local and instance variables may be declared
  final so they can be assigned a value only once
• Yabbadabba out to reality FinalVariables.java

20
The Math Class

• The Math class in the java.lang package includes
  many common and useful mathematical functions
  such sin, cos, tan, square root, exponentiation,
  and others.
• The mathematical formula
• is expressed in Java as
• Math.abs( Math.sin( Math.PI / 4.0) x )
• Splodge out to reality MathFunctions.java