Class AttributeValueExp

All Implemented Interfaces:
Serializable, ValueExp 
public class AttributeValueExp
extends Object
implements ValueExp

Represents attributes used as arguments to relational constraints. Instances of this class are usually obtained using Query.attr.

An AttributeValueExp may be used anywhere a ValueExp is required.

Since:
1.5
See Also:
Serialized Form

Constructor Summary

Constructors
Constructor Description
AttributeValueExp()

Deprecated.

An instance created with this constructor cannot be used in a query.
AttributeValueExp​(String attr)

Creates a new AttributeValueExp representing the specified object attribute, named attr.

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type Method Description
ValueExp apply​(ObjectName name)

Applies the AttributeValueExp on an MBean.
protected Object getAttribute​(ObjectName name)

Return the value of the given attribute in the named MBean.
String getAttributeName()

Returns a string representation of the name of the attribute.
void setMBeanServer​(MBeanServer s)

Deprecated.

This method has no effect.
String toString()

Returns the string representing its value.

Methods declared in class java.lang.Object

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

Constructor Detail

AttributeValueExp

@Deprecated
public AttributeValueExp()
Deprecated.
An instance created with this constructor cannot be used in a query.

An AttributeValueExp with a null attribute.

AttributeValueExp

public AttributeValueExp​(String attr)

Creates a new AttributeValueExp representing the specified object attribute, named attr.

Parameters:
attr - the name of the attribute whose value is the value of this ValueExp.

Method Detail

getAttributeName

public String getAttributeName()

Returns a string representation of the name of the attribute.

Returns:
the attribute name.

apply

public ValueExp apply​(ObjectName name)
               throws BadStringOperationException,
                      BadBinaryOpValueExpException,
                      BadAttributeValueExpException,
                      InvalidApplicationException

Applies the AttributeValueExp on an MBean. This method calls getAttribute(name) and wraps the result as a ValueExp. The value returned by getAttribute must be a Number, String, or Boolean; otherwise this method throws a BadAttributeValueExpException, which will cause the containing query to be false for this name.

Specified by:
apply in interface ValueExp
Parameters:
name - The name of the MBean on which the AttributeValueExp will be applied.
Returns:
The ValueExp.
Throws:
BadStringOperationException - when an invalid string operation is passed to a method for constructing a query
BadBinaryOpValueExpException - when an invalid expression is passed to a method for constructing a query
BadAttributeValueExpException - when an invalid MBean attribute is passed to a query constructing method
InvalidApplicationException - when an invalid apply is attempted

toString

public String toString()

Returns the string representing its value.

Overrides:
toString in class Object
Returns:
a string representation of the object.

setMBeanServer

@Deprecated
public void setMBeanServer​(MBeanServer s)
Deprecated.
This method has no effect. The MBean Server used to obtain an attribute value is QueryEval.getMBeanServer().

Sets the MBean server on which the query is to be performed.

Specified by:
setMBeanServer in interface ValueExp
Parameters:
s - The MBean server on which the query is to be performed.

getAttribute

protected Object getAttribute​(ObjectName name)

Return the value of the given attribute in the named MBean. If the attempt to access the attribute generates an exception, return null.

The MBean Server used is the one returned by QueryEval.getMBeanServer().

Parameters:
name - the name of the MBean whose attribute is to be returned.
Returns:
the value of the attribute, or null if it could not be obtained.