ca.roumani.i2c

Class Utility

java.lang.Object

ca.roumani.i2c.Utility

public class Utility
extends java.lang.Object

This class contains various utilities. Refer to the Prof Roumani's textbooks for details.

Version:

0.1

Author:

H. Roumani, prof@roumani.ca

Method Summary

Modifier and Type	Method and Description
static void	crash(boolean condition, java.lang.String msg) Test the passed condition and throw an exception if it is true.
static double	factorial(int n) Determine the factorial of the passed integer.
static int	gcd(int a, int b) Determine the GCD (Greatest Common Divisor) of the two passed integers.
static double	getBMI(double weight, java.lang.String height) Compute the body mass index.
static int	gf(int x) Determine the Greatest Factor (GF) of the passed integer.
static java.lang.String	m2FtInch(double h) Convert from meters to feet and inches.
static double	mark() Mark the current time and determine the elapsed time since the last invocation.
static double	mortgagePayment(double amount, double rate, int period) Compute the monthly payment on a mortgage assuming constant payments and constant interest rate.
static java.lang.String	repeat(int count, char c) Create a string containing the passed character repeated as many times as specified.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

crash

public static void crash(boolean condition,
                         java.lang.String msg)

Test the passed condition and throw an exception if it is true. Otherwise do nothing. This is a convenience method to be used in lieu of an if and a throw statements.

Parameters:

condition - to test.

msg - a custom exception message.

Throws:

java.lang.RuntimeException - (with the passed message)

repeat

public static java.lang.String repeat(int count,
                                      char c)

Create a string containing the passed character repeated as many times as specified. If count is less than 1, a zero-length string is returned.

Parameters:

count - the number of repetitions.

c - the character to be repeated.

Returns:

a string containing count repetitions of c.

mortgagePayment

public static double mortgagePayment(double amount,
                                     double rate,
                                     int period)

Compute the monthly payment on a mortgage assuming constant payments and constant interest rate.

Parameters:

amount - the present value

rate - the interest rate as an annualized percent, i.e. pass 4.5 for 4.5%

period - the amortization period in years

Returns:

the monthly payment

Throws:

java.lang.RuntimeException - if amount < 0, rate ≤ 0, or rate ≥ 100

getBMI

public static double getBMI(double weight,
                            java.lang.String height)

Compute the body mass index.

Parameters:

weight - the weight in pounds. To be valid, weight must be positive.

height - the height in feet'inches. To be valid, height must have a feet component (a positive integer) optionally followed by an inches component (a non-negative integer less than 12). And if both components are present then they must be separated by a single quote.

Returns:

the body mass index (BMI) for the given weight and height

Throws:

java.lang.RuntimeException - if either weight or height is not valid as defined above.

factorial

public static double factorial(int n)

Determine the factorial of the passed integer.

Parameters:

n - a non-negative integer

Returns:

the factorial of n, n!.

Throws:

java.lang.RuntimeException - if n is negative.

gcd

public static int gcd(int a,
                      int b)

Determine the GCD (Greatest Common Divisor) of the two passed integers.

Parameters:

a - a positive integer.

b - a positive integer.

Returns:

GCD(a,b).

Throws:

java.lang.RuntimeException - if either integer is not positive.

gf

public static int gf(int x)

Determine the Greatest Factor (GF) of the passed integer. A factor of a positive integer x is an integer in [1,x) that divides x evenly.

Parameters:

x - the positive integer to factor.

Returns:

the greatest factor of x.

Throws:

java.lang.RuntimeException - if x ≤ 0.

m2FtInch

public static java.lang.String m2FtInch(double h)

Convert from meters to feet and inches.

Parameters:

h - the meter amount to be converted.

Returns:

the same amount in the format F'I" where F and I are the corresponding feet and inches. The inches are rounded to the nearest inch.

mark

public static double mark()

Mark the current time and determine the elapsed time since the last invocation.

Returns:

the number of milliseconds that have elapsed since this method was called last.