org.josql.expressions
Class ConstantExpression

java.lang.Object
  org.josql.expressions.Expression
      org.josql.expressions.ValueExpression
          org.josql.expressions.ConstantExpression

public class ConstantExpression
extends ValueExpression

This class represents a constant String or number. ALL numbers in JoSQL are represented by double.

Constructor Summary

ConstantExpression()

Method Summary

Object	evaluate(Object o, Query q) Get the value of this constant.
Class	getExpectedReturnType(Query q) Get the expected return type.
Object	getValue(Object o, Query q) Get the value of this constant.
boolean	hasFixedResult(Query q) Always returns true, well duh!
void	init(Query q) Inits the expression, in reality does nothing here, can't init a constant!
boolean	isTrue(Object o, Query q) Returns whether the value of this constant represents a true value.
void	setValue(Object v)
String	toString() Returns a string representation of this constant.

Methods inherited from class org.josql.expressions.Expression

isBracketed, setBracketed

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantExpression

public ConstantExpression()

Method Detail

getExpectedReturnType

public Class getExpectedReturnType(Query q)

Get the expected return type. Will be either: java.lang.String.class or: java.lang.Double.class.

Specified by:

getExpectedReturnType in class Expression

Parameters:

q - The Query object.

Returns:

The expected class.

init

public void init(Query q)

Inits the expression, in reality does nothing here, can't init a constant!

Specified by:

init in class Expression

Parameters:

q - The Query object.

setValue

public void setValue(Object v)

isTrue

public boolean isTrue(Object o,
                      Query q)

Returns whether the value of this constant represents a true value. See: ArithmeticExpression.isTrue(Object,Query) for details of how the return value is determined.

Specified by:

isTrue in class Expression

Parameters:

o - The current object. Not used in this method.

q - The Query object.

Returns:

true if the constant evaluates to true.

getValue

public Object getValue(Object o,
                       Query q)

Get the value of this constant.

Overrides:

getValue in class ValueExpression

Parameters:

o - The current object, not used in this method.

q - The Query object, not used in this method.

Returns:

The constant value.

evaluate

public Object evaluate(Object o,
                       Query q)

Get the value of this constant.

Specified by:

evaluate in class ValueExpression

Parameters:

o - The current object, not used in this method.

q - The Query object, not used in this method.

Returns:

The constant value.

hasFixedResult

public boolean hasFixedResult(Query q)

Always returns true, well duh!

Specified by:

hasFixedResult in class Expression

Parameters:

q - The Query object.

Returns:

true always.

toString

public String toString()

Returns a string representation of this constant. If the constant is a String then it should be noted that the original quoting character is not kept in this class and the output of this method will contain the character "'" instead. If the constant is a number then "toString" is called on it, so any "," or other number formatting will have been lost.

Specified by:

toString in class Expression

Returns:

A string representation of this constant.