edu.hws.jcm.awt
Class VariableInput

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.TextComponent
              |
              +--java.awt.TextField
                    |
                    +--edu.hws.jcm.awt.VariableInput

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.image.ImageObserver, InputObject, java.awt.MenuContainer, java.io.Serializable, Tieable, Value

public class VariableInput

extends java.awt.TextField

implements InputObject, Tieable, Value

A VariableInput is an input box into which the user can type a real number value, which becomes the value of an associated Variable. The value of the Variable can change only when the VariableInput's checkInput() method is called (usually by a Controller). See the Controller class for more information.

Whenever checkInput is called, an error of type JCMError might be generated. If throwErrors is true, this error is thrown; if it is false, the error is caught, the value of the variable is set to Double.NaN, and no error is thrown. The error message associated with the error can be retrieved by calling getErrorMessage(), if desired. (This value is null if no error occurred the last time checkInput was called.)

A VariableInput is a Value, so it can be used directly where a Value object is needed.

An VariableInput will ordinarily be registered with a Controller in TWO ways: It's added to a Controller with the Controller's add() method. This makes the Controller call the VariableInput's checkInput() method during the Controller's compute() method. Secondly, a Controller is set as the "onUserAction" property. This causes the Controller's compute() method to be called when the user presses return in the VariableInput box. This is optional-- you might, for example, only want the Controller to compute() when a Compute button is pressed. You can also set the VariableInput's onTextChange property to a Controller that you want to compute every time the text in the box changes.

After the VariableInput is created, it is possible to specify the largest and smallest allowed values for the variable. It is also possible to specify what sytle of input is allowed. The style can be to allow any constant expression, constant real numbers only, or integers only. Set these parameters with setMin(), setMax(), and setInputStyle(). For setInputStyle(), the legal parameter values are VariableInput.EXPRESSION, VariableInput.REAL, and VariableInput.INTEGER. The default input style is EXPRESSION.

See Also:

Serialized Form

Inner classes inherited from class java.awt.TextField

java.awt.TextField.AccessibleAWTTextField

Inner classes inherited from class java.awt.TextComponent

java.awt.TextComponent.AccessibleAWTTextComponent

Inner classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent

Field Summary

protected java.lang.String	errorMessage Error message from the most recent time checkInput() as called.
static int	EXPRESSION A constant for use in the setInputStyle() method.
protected boolean	hasChanged This is set to true if the text in the box has been changed since the last time the value of the variable was checked by checkInput().
protected int	inputStyle One of the constant values EXPRESSION, REAL, or INTEGER, specifying the style of input.
static int	INTEGER A constant for use in the setInputStyle() method.
protected double	maxValue Largest allowable value.
protected double	minValue Smallest allowable value.
static int	REAL A constant for use in the setInputStyle() method.
protected long	serialNumber This serial number is increased each time the value of the variable changes.
protected boolean	throwErrors True if an error should be thrown when checkInput() is calles and the contents do not define a legal number.
protected edu.hws.jcm.awt.VariableInput.VI	variable The Variable that represents the value of this input box.

Fields inherited from class java.awt.TextComponent

textListener

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

VariableInput()
Create an unnamed VariableInput with initial contents "0".

VariableInput(java.lang.String name, java.lang.String initialString)
Construct a VariableInput with the given name and initial String (which can both be null).

VariableInput(java.lang.String name, java.lang.String initialString, Parser parser)
Create a VariableInput just as in the constructor VariableInput(String,String).

Method Summary

void	addTo(Parser p) A convenience method that registers this VariableInput's variable with Parser p (but only if both p and the name of the variable are non-null).
void	checkInput() Check whether the contents are valid, and change the value of the associated variable if the new contents do not match the current value.
protected double	convertInput(java.lang.String num) Convert a string into a real value.
java.lang.String	getErrorMessage() Get error message from previous call to checkInput().
int	getInputStyle() Return the input style, which determines what types of things are allowed in the input box.
double	getMax() Return the maximum value that will be accepted in this VariableInput box.
double	getMin() Return the minimum value that will be accepted in this VariableInput box.
Controller	getOnTextChange() Return the Controller, if any, that is notified when the text in this input box changes
Controller	getOnUserAction() Return the Controller, if any, that is notified when the user presses return in this text-input box.
long	getSerialNumber() Return this object's serial number, which increases whenever the value of the associated variable changes.
boolean	getThrowErrors() Return the value of the throwErrors property.
double	getVal() Return the value of the associated variable, which might not reflect the value of the contents of the input box.
Variable	getVariable() Get the associated variable for the VariableInput box.
void	notifyControllerOnChange(Controller c) Method required by InputObject interface; in this class, it simply calls setOnUserAction(c).
void	processActionEvent(java.awt.event.ActionEvent evt) Overridden to call onUserAction.compute() if onUserAction is non-null.
void	processKeyEvent(java.awt.event.KeyEvent evt) Override processKeyEvent to only allow characters that are legal in this VariableInput.
void	processTextEvent(java.awt.event.TextEvent evt) Overridden to call onUserAction.compute() if onUserAction is non-null.
void	setInputStyle(int style) Specify what types of things are allowed in the input box.
void	setMax(double max) Specify the largest allowed value for the content of this VariableInput box.
void	setMin(double min) Specify the smallest allowed value for the content of this VariableInput box.
void	setName(java.lang.String name) Set the name of the variable.
void	setOnTextChange(Controller c) If the Controller, cm is non-null, then its compute() method will be called whenever the text in this input box changes.
void	setOnUserAction(Controller c) If the Controller, c, is non-null, then its compute() method will be called whenever the user presses the return key while typing in this text-input box.
void	setText(java.lang.String text) This overrides the setText() method from the TextField class so that it will also force the contents to be checked the next time the checkInput() method is called.
void	setThrowErrors(boolean throwErrors) Set the throwErrors property.
void	setVal(double d) Set the value of the associated variable.
void	sync(Tie tie, Tieable newest) Synchronize serial number and value with newest, unless this VariableInput is itself newest.
JCMPanel	withLabel() Convenience method for creating a component containing this VariableInput together with a label of the form " = ".
JCMPanel	withLabel(java.awt.Color back, java.awt.Color fore) Convenience method for creating a component containing this VariableInput together with a label of the form "name = ".

Methods inherited from class java.awt.TextField

addActionListener, addNotify, echoCharIsSet, getAccessibleContext, getColumns, getEchoChar, getListeners, getMinimumSize, getMinimumSize, getPreferredSize, getPreferredSize, minimumSize, minimumSize, paramString, preferredSize, preferredSize, processEvent, removeActionListener, setColumns, setEchoChar, setEchoCharacter

Methods inherited from class java.awt.TextComponent

addTextListener, getBackground, getCaretPosition, getSelectedText, getSelectionEnd, getSelectionStart, getText, isEditable, removeNotify, removeTextListener, select, selectAll, setBackground, setCaretPosition, setEditable, setSelectionEnd, setSelectionStart

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getName, getParent, getPeer, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate

Methods inherited from class java.lang.Object

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

Field Detail

variable

protected edu.hws.jcm.awt.VariableInput.VI variable

The Variable that represents the value of this input box. (VI is a private nested class inside VariableInput.)

throwErrors

protected boolean throwErrors

True if an error should be thrown when checkInput() is calles and the contents do not define a legal number. True by default.

errorMessage

protected java.lang.String errorMessage

Error message from the most recent time checkInput() as called. Null if there was no error.

serialNumber

protected long serialNumber

This serial number is increased each time the value of the variable changes.

hasChanged

protected boolean hasChanged

This is set to true if the text in the box has been changed since the last time the value of the variable was checked by checkInput().

minValue

protected double minValue

Smallest allowable value.

maxValue

protected double maxValue

Largest allowable value.

inputStyle

protected int inputStyle

One of the constant values EXPRESSION, REAL, or INTEGER, specifying the style of input.

EXPRESSION

public static final int EXPRESSION

A constant for use in the setInputStyle() method. Any constant expression is allowed.

REAL

public static final int REAL

A constant for use in the setInputStyle() method. Only real numbers are allowed.

INTEGER

public static final int INTEGER

A constant for use in the setInputStyle() method. Only integers are allowed.

Constructor Detail

VariableInput

public VariableInput()

Create an unnamed VariableInput with initial contents "0".

VariableInput

public VariableInput(java.lang.String name,
                     java.lang.String initialString)

Construct a VariableInput with the given name and initial String (which can both be null). If initialString is null, the string "0" is used. No error occurs in the constructor if the initialString does not represent a legal value (A string rather than a double is used for initialization since the initial content can be an expression such as "pi/2".) If name is not null, it is used as the name of the VariableInput component as well as the name of the associated variable.

VariableInput

public VariableInput(java.lang.String name,
                     java.lang.String initialString,
                     Parser parser)

Create a VariableInput just as in the constructor VariableInput(String,String). Then, if both parser and name are non-null, register the associated variable with the parser.

Method Detail

getVariable

public Variable getVariable()

Get the associated variable for the VariableInput box. You will need this, for example, if you want to register the variable with a Parser.

withLabel

public JCMPanel withLabel()

Convenience method for creating a component containing this VariableInput together with a label of the form " = ". This version uses default colors for the label, which are inherited from the containing component.

withLabel

public JCMPanel withLabel(java.awt.Color back,
                          java.awt.Color fore)

Convenience method for creating a component containing this VariableInput together with a label of the form "name = ". Uses the given background and foreground colors for the label and the panel. The colors can be null to use the defaults, which will be inherited from the containing Component.

setName

public void setName(java.lang.String name)

Set the name of the variable. This should not be called while the variable is registered with a Parser. The name of the VariableInput Component is also set to name, if the name is non=null.

Overrides:

setName in class java.awt.Component

addTo

public void addTo(Parser p)

A convenience method that registers this VariableInput's variable with Parser p (but only if both p and the name of the variable are non-null).

setOnUserAction

public void setOnUserAction(Controller c)

If the Controller, c, is non-null, then its compute() method will be called whenever the user presses the return key while typing in this text-input box.

getOnUserAction

public Controller getOnUserAction()

Return the Controller, if any, that is notified when the user presses return in this text-input box.

notifyControllerOnChange

public void notifyControllerOnChange(Controller c)

Method required by InputObject interface; in this class, it simply calls setOnUserAction(c). This is meant to be called by JCMPanel.gatherInputs().

Specified by:

notifyControllerOnChange in interface InputObject

setOnTextChange

public void setOnTextChange(Controller c)

If the Controller, cm is non-null, then its compute() method will be called whenever the text in this input box changes. Furthermore, the throwErrors property will be set to false, to avoid throwing multiple errors while the user is typing. (You can change it back to true if you want by calling setThrowErrors(true).)

getOnTextChange

public Controller getOnTextChange()

Return the Controller, if any, that is notified when the text in this input box changes

getVal

public double getVal()

Return the value of the associated variable, which might not reflect the value of the contents of the input box. The value of the variable changes only when the checkInput() method is called, or when the setVal() method is called. Call checkInput() first, if you want to be sure of getting the same value that is currently shown in the box.

Specified by:

getVal in interface Value

setVal

public void setVal(double d)

Set the value of the associated variable. Also sets the content of the input box.

setThrowErrors

public void setThrowErrors(boolean throwErrors)

Set the throwErrors property. If the value is true, then an error will be thrown by the checkInput() method when the contents of the VariableInput box are not legal. Otherwise, no error is thrown; the value of the variable is just set to Double.NaN.

getThrowErrors

public boolean getThrowErrors()

Return the value of the throwErrors property.

setMin

public void setMin(double min)

Specify the smallest allowed value for the content of this VariableInput box.

getMin

public double getMin()

Return the minimum value that will be accepted in this VariableInput box.

setMax

public void setMax(double max)

Specify the largest allowed value for the content of this VariableInput box.

getMax

public double getMax()

Return the maximum value that will be accepted in this VariableInput box.

setInputStyle

public void setInputStyle(int style)

Specify what types of things are allowed in the input box. The value of the parameter, style, must be one of the constants VariableInput.EXPRESSION, VariableInput.REAL, or VariableInput.INTEGER. If not, the call to setInputStyle is ignored.

getInputStyle

public int getInputStyle()

Return the input style, which determines what types of things are allowed in the input box. The returned value is one of the contstants EXPRESSION, REAL, or INTEGER

getErrorMessage

public java.lang.String getErrorMessage()

Get error message from previous call to checkInput(). Returns null if there was no error.

checkInput

public void checkInput()

Check whether the contents are valid, and change the value of the associated variable if the new contents do not match the current value. This might throw an error of type JCMError, if throwErrors is true. This is usually called by a Controller.

Specified by:

checkInput in interface InputObject

getSerialNumber

public long getSerialNumber()

Return this object's serial number, which increases whenever the value of the associated variable changes.

Specified by:

getSerialNumber in interface Tieable

sync

public void sync(Tie tie,
                 Tieable newest)

Synchronize serial number and value with newest, unless this VariableInput is itself newest. This is required by the Tieable interface, and is usually called by an object of type Tie.

Specified by:

sync in interface Tieable

convertInput

protected double convertInput(java.lang.String num)

Convert a string into a real value. The parameter is taken from the input box when this method is called by VI.checkInput() Throw a JCMError if any error is found in the input.

Parameters:

num - String to be converted

Returns:

the real value.

processKeyEvent

public void processKeyEvent(java.awt.event.KeyEvent evt)

Override processKeyEvent to only allow characters that are legal in this VariableInput.

Overrides:

processKeyEvent in class java.awt.Component

Parameters:

evt - used internally.

setText

public void setText(java.lang.String text)

This overrides the setText() method from the TextField class so that it will also force the contents to be checked the next time the checkInput() method is called.

Overrides:

setText in class java.awt.TextField

Parameters:

text - change text to this.

processActionEvent

public void processActionEvent(java.awt.event.ActionEvent evt)

Overridden to call onUserAction.compute() if onUserAction is non-null. This is not meant to be called directly.

Overrides:

processActionEvent in class java.awt.TextField

processTextEvent

public void processTextEvent(java.awt.event.TextEvent evt)

Overridden to call onUserAction.compute() if onUserAction is non-null. This is not meant to be called directly.

Overrides:

processTextEvent in class java.awt.TextComponent