vmm.core
Class Util

java.lang.Object
  vmm.core.Util

public class Util
extends java.lang.Object

Provides several static utility funtions that can be used in various places.

Constructor Summary

Util()

Method Summary

static long	availableMemory() Tries to compute the amount of memory that is available and not yet used.
static java.awt.Cursor	createCursorFromResource(java.lang.String imageResourceFileName, int activeX, int activeY) A method that creates a cursor from an image file.
static java.lang.String[]	explode(java.lang.String str, java.lang.String separators) A convenience method that breaks up a string into tokens, where the tokens are substrings seprated by specified delimiters.
static java.lang.Object	externalStringToValue(java.lang.String str, java.lang.Class valueType) Tries to convert a string to a value of a specified type.
static javax.swing.KeyStroke	getAccelerator(java.lang.String description) Returns a KeyStroke, typically for use as the accelerator for a menu command.
static java.awt.geom.Point2D	getPoint2DFromUser(java.awt.Component parent, java.lang.String prompt)
static java.awt.geom.Point2D	getPoint2DFromUser(java.awt.Component parent, java.lang.String prompt, double initialX, double initialY)
static java.awt.geom.Point2D	getPoint2DFromUser(java.awt.Component parent, java.lang.String prompt, double initialX, double initialY, java.lang.String nameForX, java.lang.String nameForY)
static boolean	isMacOS() Test whether the program is running on Mac OS.
static ComplexExpression	parseComplexConstantExpression(java.lang.String expressionAsString) Parses a string to produce a constant ComplexExpression.
static Expression	parseConstantExpression(java.lang.String expressionAsString) Parses a string to produce a constant Expression.
static java.lang.String	toExternalString(java.lang.Object value) Converts any value to a string -- hopefull a string that can be parsed by externalStringToValue(String, Class) to recover the original value.

Methods inherited from class java.lang.Object

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

Constructor Detail

Util

public Util()

Method Detail

parseConstantExpression

public static Expression parseConstantExpression(java.lang.String expressionAsString)
                                          throws ParseError

Parses a string to produce a constant Expression. A default Parser is used to do the parsing.

Parameters:

expressionAsString - The constant expression, represented as a string. A ParseError is thrown if this is not a legal real-valued expression.

Returns:

The expression represented by the string

Throws:

ParseError

parseComplexConstantExpression

public static ComplexExpression parseComplexConstantExpression(java.lang.String expressionAsString)
                                                        throws ParseError

Parses a string to produce a constant ComplexExpression. A default Parser is used to do the parsing.

Parameters:

expressionAsString - The constant expression, represented as a string. A ParseError is thrown if this is not a legal complex expression.

Returns:

The expression represented by the string

Throws:

ParseError

createCursorFromResource

public static java.awt.Cursor createCursorFromResource(java.lang.String imageResourceFileName,
                                                       int activeX,
                                                       int activeY)

A method that creates a cursor from an image file. The image file is obtained as a resource using the getResource method of the Toolkit class. If the resource is not found or if any other error occurs, then the return value of the method will be null. The second and third parameters specify the active point of the cursor -- the point that determines the (x,y) position of the cursor in mouse events.

isMacOS

public static boolean isMacOS()

Test whether the program is running on Mac OS.

getAccelerator

public static javax.swing.KeyStroke getAccelerator(java.lang.String description)

Returns a KeyStroke, typically for use as the accelerator for a menu command. Depending on the OS, either "control" or "meta" will be added to the description that is passed to this method. The descriptions might be just a key name, such as "A", or it might include modifier keys, such as "shift A" or "alt A".

availableMemory

public static long availableMemory()

Tries to compute the amount of memory that is available and not yet used.

getPoint2DFromUser

public static java.awt.geom.Point2D getPoint2DFromUser(java.awt.Component parent,
                                                       java.lang.String prompt)

getPoint2DFromUser

public static java.awt.geom.Point2D getPoint2DFromUser(java.awt.Component parent,
                                                       java.lang.String prompt,
                                                       double initialX,
                                                       double initialY)

getPoint2DFromUser

public static java.awt.geom.Point2D getPoint2DFromUser(java.awt.Component parent,
                                                       java.lang.String prompt,
                                                       double initialX,
                                                       double initialY,
                                                       java.lang.String nameForX,
                                                       java.lang.String nameForY)

explode

public static java.lang.String[] explode(java.lang.String str,
                                         java.lang.String separators)

A convenience method that breaks up a string into tokens, where the tokens are substrings seprated by specified delimiters. For example, explode("ab,cde,f,ghij", ",") produces an array of the four substrings "ab" "cde" "f" "ghi".

Parameters:

str - the string that is to be exploded; if null, then the return value is null

separators - characters in this string are separatos between tokens in the string that is being exploded. If this is null, then the return value will be an array of length one containing str as its only element.

toExternalString

public static java.lang.String toExternalString(java.lang.Object value)

Converts any value to a string -- hopefull a string that can be parsed by externalStringToValue(String, Class) to recover the original value. This method definitely works for: the wrapper types such as Double, Complex, Color, Point2D, Vector3D, double[], int[]. For other types, this method returns value.toString(), which might work. In no case does it throw an exception. Note that a null value is converted to the string "##NULL##". For double and float numbers, the special strings NaN, +INF, -INF, and EPSILON are used to represent the special values Not-a-number, positive infinity, negative infinity, and min_value (the smallest positive value). This method is used in SaveAndRestore and in other places where conversion of an object to a string is needed.

externalStringToValue

public static java.lang.Object externalStringToValue(java.lang.String str,
                                                     java.lang.Class valueType)
                                              throws java.lang.IllegalArgumentException

Tries to convert a string to a value of a specified type. This method can handle the strings produced by toExternalString(Object) for at least the following types: the wrapper types, Color, Point2D, Complex, Vector3D, double[], and int[]. The special string "##NULL##" is converted to the value null (except in the case of primitive types.) The method will work for primitive types such as Double.TYPE. Note that for the type Double.TYPE, the return value is of type Double (just as it would be for Double.class). Aside from these built-in types, the method will try to find a static method in the class named "fromString" and with one parameter of type String. If such a method is found, it will be called and its return value will be the return value of this mthod. If no such method is found, an attempt is made to find a constructor in the class with one parameter of type String. If such a constructor is found, it is invoked to produce the return value.

An exception of type IllegalArgumentException will be thrown if none of this succeeds in producing an object of the specified type. No other type of exception will be thrown.

Throws:

java.lang.IllegalArgumentException