org.nfunk.jep

Class Variable

java.lang.Object

java.util.Observable

org.nfunk.jep.Variable

Direct Known Subclasses:

XVariable

public class Variable
extends Observable

Information about a variable. Each variable has a name, a value. There is a flag to indicate whether it is a constant or not (constants cannot have their value changed). There is also a flag to indicate whether the value of the variable is valid, if the variable is initialised without a value then its value is said to be invalid.

Version:

2.3.0 beta 2 Now extends Observable so observers can track if the value has been changed.

Author:

Rich Morris Created on 18-Nov-2003

Field Summary

Fields

Modifier and Type	Field and Description
protected String	name

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Variable(String name) Constructors are protected.
protected	Variable(String name, Object value) Constructors are protected.

Method Summary

Modifier and Type	Method and Description
String	getName()
Object	getValue()
boolean	hasValidValue() Is the value of this variable valid?
boolean	isConstant()
void	setIsConstant(boolean b)
void	setValidValue(boolean val) Sets whether the value of variable is valid.
boolean	setValue(Object object) Sets the value of the variable.
protected boolean	setValueRaw(Object object) In general subclasses should override this method rather than setValue.
String	toString() Returns a string with the variable name followed by it's value.

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

name

protected String name

Constructor Detail

Variable

protected Variable(String name)

Constructors are protected. Variables should only be created through the associated VariableFactory which are in turned called by SymbolTable.

Variable

protected Variable(String name,
                   Object value)

Constructors are protected. Variables should only be created through the associated VariableFactory which are in turned called by SymbolTable.

Method Detail

getName

public String getName()

isConstant

public boolean isConstant()

setIsConstant

public void setIsConstant(boolean b)

getValue

public Object getValue()

hasValidValue

public boolean hasValidValue()

Is the value of this variable valid?

setValidValue

public void setValidValue(boolean val)

Sets whether the value of variable is valid.

setValue

public boolean setValue(Object object)

Sets the value of the variable. Constant values cannot be changed.

This method call java.util.Observable.notifyObservers() to indicate to anyone interested that the value has been changed. Note subclasses should override setValueRaw rather than this method so they do not need to handle the Observable methods.

Returns:

false if tried to change a constant value.

Since:

2.3.0 beta 2 added Observable

setValueRaw

protected boolean setValueRaw(Object object)

In general subclasses should override this method rather than setValue. This is because setValue notifies any observers and then calls this method.

Parameters:

object -

Returns:

false if tried to change a constant value.

Since:

2.3.0 beta 2

toString

public String toString()

Returns a string with the variable name followed by it's value. For example for the variable "a" with the value 10, the following string is returned:

a: 10

If the variable is a constant the string " (Constant" is appended.

Overrides:

toString in class Object

Returns:

A string with the variable name and value.