org.mpxj.common

Class NumberHelper

java.lang.Object

org.mpxj.common.NumberHelper

public final class NumberHelper
extends Object

This class contains utility methods for handling Number objects and numeric primitives.

Field Summary

Fields

Modifier and Type	Field and Description
static Double	DOUBLE_ONEHUNDRED
static Double	DOUBLE_ZERO

Constructor Summary

Constructors

Constructor and Description
NumberHelper()

Method Summary

Modifier and Type	Method and Description
static int	compare(Integer n1, Integer n2) Compare two integers, accounting for null values.
static boolean	equals(double lhs, double rhs, double delta) Compares two doubles for equality, within an allowable range of difference.
static boolean	equals(Number lhs, Number rhs) This method is used to compare two numbers.
static BigInteger	getBigInteger(Number value) Utility method used to convert a Number into a BigInteger.
static Double	getDouble(double value) Utility method used to convert a double into a Double.
static double	getDouble(Number value) Utility method used to convert a Number into a double.
static double	getDouble(String value) This method retrieves a double value from a String instance.
static Double	getDoubleObject(String value) This method retrieves a double value from a String instance.
static int	getInt(Number value) This method retrieves an int value from a Number instance.
static int	getInt(String value) This method retrieves an int value from a String instance.
static Integer	getInteger(Number value) Utility method used to convert an arbitrary Number into an Integer.
static Integer	getInteger(String value) Converts a string representation of an integer into an Integer object.
static Integer	parseInteger(String value) Utility method to convert a String to an Integer, and handles null values.
static double	round(double value, double precision) Utility method used to round a double to the given precision.
static Double	sumAsDouble(Number... values) Calculate the sum of a list of numbers and express the result as a Double instance.

Methods inherited from class java.lang.Object

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

Field Detail

DOUBLE_ZERO

public static final Double DOUBLE_ZERO

DOUBLE_ONEHUNDRED

public static final Double DOUBLE_ONEHUNDRED

Constructor Detail

NumberHelper

public NumberHelper()

Method Detail

getInt

public static final int getInt(Number value)

This method retrieves an int value from a Number instance. It returns zero by default if a null value is supplied.

Parameters:

value - Number instance

Returns:

int value

getInt

public static final int getInt(String value)

This method retrieves an int value from a String instance. It returns zero by default if a null value or an empty string is supplied.

Parameters:

value - string representation of an integer

Returns:

int value

getDouble

public static final double getDouble(String value)

This method retrieves a double value from a String instance. It returns zero by default if a null value or an empty string is supplied.

Parameters:

value - string representation of a double

Returns:

double value

getDoubleObject

public static final Double getDoubleObject(String value)

This method retrieves a double value from a String instance. It returns null by default if a null value or an empty string is supplied.

Parameters:

value - string representation of a double

Returns:

double value

getInteger

public static final Integer getInteger(Number value)

Utility method used to convert an arbitrary Number into an Integer.

Parameters:

value - Number instance

Returns:

Integer instance

getInteger

public static final Integer getInteger(String value)

Converts a string representation of an integer into an Integer object. Silently ignores any parse exceptions and returns null.

Parameters:

value - String representation of an integer

Returns:

Integer instance

getBigInteger

public static final BigInteger getBigInteger(Number value)

Utility method used to convert a Number into a BigInteger.

Parameters:

value - Number instance

Returns:

BigInteger instance

getDouble

public static final double getDouble(Number value)

Utility method used to convert a Number into a double. This has been implemented to allow a singleton to be used to represent zero. This makes a considerable saving in memory utilisation.

Parameters:

value - Number instance

Returns:

double value

getDouble

public static final Double getDouble(double value)

Utility method used to convert a double into a Double. This has been implemented to allow a singleton to be used to represent zero. This makes a considerable saving in memory utilisation. NOTE: as of Java 1.5 the Double.valueOf method is supposed to implement caching. The current JDK 1.5 implementation doesn't appear to do this, so we'll leave this method alone for now. We can look at replacing this when we move to 1.6.

Parameters:

value - Number instance

Returns:

double value

round

public static final double round(double value,
                                 double precision)

Utility method used to round a double to the given precision.

Parameters:

value - value to truncate

precision - Number of decimals to round to.

Returns:

double value

parseInteger

public static final Integer parseInteger(String value)

Utility method to convert a String to an Integer, and handles null values.

Parameters:

value - string representation of an integer

Returns:

int value

equals

public static boolean equals(Number lhs,
                             Number rhs)

This method is used to compare two numbers. The unusual point about this method is that it takes account of null values. If the two number objects are both null, these are taken to be equal, if one is null and the other is not null, these are taken to be different. Finally, if we have two valid number objects, these are compared in the normal manner to determine equality.

Parameters:

lhs - left hand argument

rhs - right hand argument

Returns:

result of equality test

compare

public static int compare(Integer n1,
                          Integer n2)

Compare two integers, accounting for null values.

Parameters:

n1 - integer value

n2 - integer value

Returns:

comparison result

equals

public static boolean equals(double lhs,
                             double rhs,
                             double delta)

Compares two doubles for equality, within an allowable range of difference.

Parameters:

lhs - value to test

rhs - value to test

delta - allowable difference

Returns:

boolean value

sumAsDouble

public static Double sumAsDouble(Number... values)

Calculate the sum of a list of numbers and express the result as a Double instance.

Parameters:

values - list of numbers

Returns:

Double instance