org.josql.expressions

类 IsNullExpression

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.BinaryExpression

org.josql.expressions.IsNullExpression

public class IsNullExpression
extends BinaryExpression

Represents an "IS NULL" (or "IS NOT NULL") expression.

字段概要

从类继承的字段 org.josql.expressions.BinaryExpression

left, right

构造器概要

构造器

构造器和说明
IsNullExpression()

方法概要

限定符和类型	方法和说明
boolean	isNot()
boolean	isTrue(Object o, Query q) Determine whether the LHS of this expression is or is not null.
void	setNot(boolean v)
String	toString() Return a string representation of this expression.

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

getExpectedReturnType, getLeft, getRight, getValue, hasFixedResult, init, setLeft, setRight

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

IsNullExpression

public IsNullExpression()

方法详细资料

isNot

public boolean isNot()

setNot

public void setNot(boolean v)

toString

public String toString()

Return a string representation of this expression. In the form: Expression.toString() IS [ NOT ] NULL

指定者:

toString 在类中 Expression

返回:

A string representation of this expression.

isTrue

public boolean isTrue(Object o,
                      Query q)
               throws QueryExecutionException

Determine whether the LHS of this expression is or is not null. Note that this is equivalent to: LHS = null or: LHS != null.

指定者:

isTrue 在类中 Expression

参数:

o - The current object to perform the expression on.

q - The Query object.

返回:

true if the LHS is null (or not null is specified).

抛出:

QueryExecutionException - If the expression cannot be evaluated.