org.josql.expressions

类 ConstantExpression

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.ValueExpression

org.josql.expressions.ConstantExpression

public class ConstantExpression
extends ValueExpression

构造器概要

构造器

构造器和说明
ConstantExpression()

方法概要

限定符和类型	方法和说明
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.

从类继承的方法 org.josql.expressions.Expression

isBracketed, setBracketed

从类继承的方法 java.lang.Object

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

构造器详细资料

ConstantExpression

public ConstantExpression()

方法详细资料

getExpectedReturnType

public Class getExpectedReturnType(Query q)

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

指定者:

getExpectedReturnType 在类中 Expression

参数:

q - The Query object.

返回:

The expected class.

init

public void init(Query q)

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

指定者:

init 在类中 Expression

参数:

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.

指定者:

isTrue 在类中 Expression

参数:

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

q - The Query object.

返回:

true if the constant evaluates to true.

getValue

public Object getValue(Object o,
                       Query q)

Get the value of this constant.

覆盖:

getValue 在类中 ValueExpression

参数:

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

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

返回:

The constant value.

evaluate

public Object evaluate(Object o,
                       Query q)

Get the value of this constant.

指定者:

evaluate 在类中 ValueExpression

参数:

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

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

返回:

The constant value.

hasFixedResult

public boolean hasFixedResult(Query q)

Always returns true, well duh!

指定者:

hasFixedResult 在类中 Expression

参数:

q - The Query object.

返回:

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.

指定者:

toString 在类中 Expression

返回:

A string representation of this constant.