org.josql.expressions

类 BinaryExpression

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.BinaryExpression

直接已知子类:

AndOrExpression, BetweenExpression, EqualsExpression, GTLTExpression, InExpression, IsNullExpression, LikeExpression

public abstract class BinaryExpression
extends Expression

字段概要

字段

限定符和类型	字段和说明
protected Expression	left
protected Expression	right

构造器概要

构造器

构造器和说明
BinaryExpression()

方法概要

限定符和类型	方法和说明
Class	getExpectedReturnType(Query q) Return the expected return type from this expression.
Expression	getLeft() Get the LHS.
Expression	getRight() Get the RHS.
Object	getValue(Object o, Query q) Get the value of this expression.
boolean	hasFixedResult(Query q) Return whether the expression will evaluate to a fixed/constant result.
void	init(Query q) Init the expression.
void	setLeft(Expression exp)
void	setRight(Expression exp)

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

isBracketed, isTrue, setBracketed, toString

从类继承的方法 java.lang.Object

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

字段详细资料

left

protected Expression left

right

protected Expression right

构造器详细资料

BinaryExpression

public BinaryExpression()

方法详细资料

hasFixedResult

public boolean hasFixedResult(Query q)

从类复制的说明: Expression

Return whether the expression will evaluate to a fixed/constant result. This allows certain optimisations to be performed when an expression is evaluated. A "fixed result" is basically one in which multiple calls to either the: Expression.isTrue(Object,Query) or Expression.getValue(Object,Query) methods will return the same object (or that o1.equals (o2) == true) regardless of the object passed to the method.

指定者:

hasFixedResult 在类中 Expression

参数:

q - The Query object.

返回:

true if the expression evaluates to a fixed/constant result.

getExpectedReturnType

public Class getExpectedReturnType(Query q)

Return the expected return type from this expression.

指定者:

getExpectedReturnType 在类中 Expression

参数:

q - The Query object.

返回:

The class of the return type, this method ALWAYS returns Boolean.class.

init

public void init(Query q)
          throws QueryParseException

Init the expression. Sub-classes will often override this method. This method just calls: Expression.init(Query) on the LHS and RHS (if present) of the expression.

指定者:

init 在类中 Expression

参数:

q - The Query object.

抛出:

QueryParseException - If the LHS and/or RHS cannot be inited.

getValue

public Object getValue(Object o,
                       Query q)
                throws QueryExecutionException

Get the value of this expression. This will always return an instance of: java.lang.Boolean created as the result of a call to: Expression.getValue(Object,Query).

指定者:

getValue 在类中 Expression

参数:

o - The object to evaluate the expression on.

q - The Query object.

返回:

An instance of Boolean.

抛出:

QueryExecutionException - If the expression cannot be evaluated.

getRight

public Expression getRight()

Get the RHS.

返回:

The RHS of the expression.

getLeft

public Expression getLeft()

Get the LHS.

返回:

The LHS of the expression.

setLeft

public void setLeft(Expression exp)

setRight

public void setRight(Expression exp)