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package com.sun.jdi;
The mirror for a value in the target VM.
This interface is the root of a
value hierarchy encompassing primitive values and object values.
Some examples of where values may be accessed:
ObjectReference.getValue(Field) - value of a field
StackFrame.getValue(LocalVariable) - value of a variable
VirtualMachine.mirrorOf(double) - created in the target VM by the JDI client
ModificationWatchpointEvent.valueToBe() - returned with an event
The following table illustrates which subinterfaces of Value
are used to mirror values in the target VM --
Subinterfaces of PrimitiveValue
Kind of value
For example -
expression in target
Is mirrored as an
instance of
Type of value
Value.type()
a boolean
true
BooleanValue
BooleanType
a byte
(byte)4
ByteValue
ByteType
a char
'a'
CharValue
CharType
a double
3.1415926
DoubleValue
DoubleType
a float
2.5f
FloatValue
FloatType
an int
22
IntegerValue
IntegerType
a long
1024L
LongValue
LongType
a short
(short)12
ShortValue
ShortType
a void
VoidValue
VoidType
Subinterfaces of ObjectReference
Kind of value
For example -
expression in target
Is mirrored as an
instance of
Type of value
Value.type()
a class instance
this
ObjectReference
ClassType
an array
new int[5]
ArrayReference
ArrayType
a string
"hello"
StringReference
ClassType
a thread
Thread.currentThread()
ThreadReference
ClassType
a thread group
Thread.currentThread()
.getThreadGroup()
ThreadGroupReference
ClassType
a java.lang.Class
instance
this.getClass()
ClassObjectReference
ClassType
a class loader
this.getClass()
.getClassLoader()
ClassLoaderReference
ClassType
Other
Kind of value
For example -
expression in target
Is mirrored as
Type of value
null
null
null
n/a
Author: Robert Field, Gordon Hirsch, James McIlree Since: 1.3
/**
* The mirror for a value in the target VM.
* This interface is the root of a
* value hierarchy encompassing primitive values and object values.
* <P>
* Some examples of where values may be accessed:
* <BLOCKQUOTE><TABLE SUMMARY="layout">
* <TR>
* <TD>{@link ObjectReference#getValue(com.sun.jdi.Field)
* ObjectReference.getValue(Field)}
* <TD>- value of a field
* <TR>
* <TD>{@link StackFrame#getValue(com.sun.jdi.LocalVariable)
* StackFrame.getValue(LocalVariable)}
* <TD>- value of a variable
* <TR>
* <TD>{@link VirtualMachine#mirrorOf(double)
* VirtualMachine.mirrorOf(double)}
* <TD>- created in the target VM by the JDI client
* <TR>
* <TD>{@link com.sun.jdi.event.ModificationWatchpointEvent#valueToBe()
* ModificationWatchpointEvent.valueToBe()}
* <TD>- returned with an event
* </TABLE></BLOCKQUOTE>
* <P>
* The following table illustrates which subinterfaces of Value
* are used to mirror values in the target VM --
* <TABLE BORDER=1 SUMMARY="Maps each kind of value to a mirrored
* instance of a subinterface of Value">
* <TR BGCOLOR="#EEEEFF">
* <TH id="primval" colspan=4>Subinterfaces of {@link PrimitiveValue}</TH>
* <TR BGCOLOR="#EEEEFF">
* <TH id="kind" align="left">Kind of value</TH>
* <TH id="example" align="left">For example -<br>expression in target</TH>
* <TH id="mirrored" align="left">Is mirrored as an<br>instance of</TH>
* <TH id="type" align="left">{@link Type} of value<br>{@link #type() Value.type()}</TH>
* <TR>
* <TD headers="primval kind"> a boolean</TD>
* <TD headers="primval example"> <CODE>true</CODE></TD>
* <TD headers="primval mirrored"> {@link BooleanValue}</TD>
* <TD headers="primval type"> {@link BooleanType}</TD>
* <TR>
* <TD headers="primval kind"> a byte</TD>
* <TD headers="primval example"> <CODE>(byte)4</CODE></TD>
* <TD headers="primval mirrored"> {@link ByteValue}</TD>
* <TD headers="primval type"> {@link ByteType}</TD>
* <TR>
* <TD headers="primval kind"> a char</TD>
* <TD headers="primval example"> <CODE>'a'</CODE></TD>
* <TD headers="primval mirrored"> {@link CharValue}</TD>
* <TD headers="primval type"> {@link CharType}</TD>
* <TR>
* <TD headers="primval kind"> a double</TD>
* <TD headers="primval example"> <CODE>3.1415926</CODE></TD>
* <TD headers="primval mirrored"> {@link DoubleValue}</TD>
* <TD headers="primval type"> {@link DoubleType}</TD>
* <TR>
* <TD headers="primval kind"> a float</TD>
* <TD headers="primval example"> <CODE>2.5f</CODE></TD>
* <TD headers="primval mirrored"> {@link FloatValue}</TD>
* <TD headers="primval type"> {@link FloatType}</TD>
* <TR>
* <TD headers="primval kind"> an int</TD>
* <TD headers="primval example"> <CODE>22</CODE></TD>
* <TD headers="primval mirrored"> {@link IntegerValue}</TD>
* <TD headers="primval type"> {@link IntegerType}</TD>
* <TR>
* <TD headers="primval kind"> a long</TD>
* <TD headers="primval example"> <CODE>1024L</CODE></TD>
* <TD headers="primval mirrored"> {@link LongValue}</TD>
* <TD headers="primval type"> {@link LongType}</TD>
* <TR>
* <TD headers="primval kind"> a short</TD>
* <TD headers="primval example"> <CODE>(short)12</CODE></TD>
* <TD headers="primval mirrored"> {@link ShortValue}</TD>
* <TD headers="primval type"> {@link ShortType}</TD>
* <TR>
* <TD headers="primval kind"> a void</TD>
* <TD headers="primval example"> <CODE> </CODE></TD>
* <TD headers="primval mirrored"> {@link VoidValue}</TD>
* <TD headers="primval type"> {@link VoidType}</TD>
* <TR BGCOLOR="#EEEEFF">
* <TH id="objref" colspan=4>Subinterfaces of {@link ObjectReference}</TH>
* <TR BGCOLOR="#EEEEFF">
* <TH id="kind2" align="left">Kind of value</TH>
* <TH id="example2" align="left">For example -<br>expression in target</TH>
* <TH id="mirrored2" align="left">Is mirrored as an<br>instance of</TH>
* <TH id="type2" align="left">{@link Type} of value<br>{@link #type() Value.type()}</TH>
* <TR>
* <TD headers="objref kind2"> a class instance</TD>
* <TD headers="objref example2"> <CODE>this</CODE></TD>
* <TD headers="objref mirrored2"> {@link ObjectReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR>
* <TD headers="objref kind2"> an array</TD>
* <TD headers="objref example2"> <CODE>new int[5]</CODE></TD>
* <TD headers="objref mirrored2"> {@link ArrayReference}</TD>
* <TD headers="objref type2"> {@link ArrayType}</TD>
* <TR>
* <TD headers="objref kind2"> a string</TD>
* <TD headers="objref example2"> <CODE>"hello"</CODE></TD>
* <TD headers="objref mirrored2"> {@link StringReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR>
* <TD headers="objref kind2"> a thread</TD>
* <TD headers="objref example2"> <CODE>Thread.currentThread()</CODE></TD>
* <TD headers="objref mirrored2"> {@link ThreadReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR>
* <TD headers="objref kind2"> a thread group</TD>
* <TD headers="objref example2"> <CODE>Thread.currentThread()<br> .getThreadGroup()</CODE></TD>
* <TD headers="objref mirrored2"> {@link ThreadGroupReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR>
* <TD headers="objref kind2"> a <CODE>java.lang.Class</CODE><br>instance</TD>
* <TD headers="objref example2"> <CODE>this.getClass()</CODE></TD>
* <TD headers="objref mirrored2"> {@link ClassObjectReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR>
* <TD headers="objref kind2"> a class loader</TD>
* <TD headers="objref example2"> <CODE>this.getClass()<br> .getClassLoader() </CODE></TD>
* <TD headers="objref mirrored2"> {@link ClassLoaderReference}</TD>
* <TD headers="objref type2"> {@link ClassType}</TD>
* <TR BGCOLOR="#EEEEFF">
* <TH id="other" colspan=4>Other</TH>
* <TR BGCOLOR="#EEEEFF">
* <TH id="kind3" align="left">Kind of value</TD>
* <TH id="example3" align="left">For example -<br>expression in target</TD>
* <TH id="mirrored3" align="left">Is mirrored as</TD>
* <TH id="type3" align="left">{@link Type} of value</TD>
* <TR>
* <TD headers="other kind3"> null</TD>
* <TD headers="other example3"> <CODE>null</CODE></TD>
* <TD headers="other mirrored3"> <CODE>null</CODE></TD>
* <TD headers="other type3"> n/a</TD>
* </TABLE>
*
* @author Robert Field
* @author Gordon Hirsch
* @author James McIlree
* @since 1.3
*/
public interface Value extends Mirror
{
Returns the run-time type of this value.
See Also: - Type
Returns: a Type which mirrors the value's type in the target VM.
/**
* Returns the run-time type of this value.
*
* @see Type
* @return a {@link Type} which mirrors the value's type in the
* target VM.
*/
Type type();
}