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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:

layout
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 --

Maps each kind of value to a mirrored instance of a subinterface of Value
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><CAPTION style="display:none">layout</CAPTION> * <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"> * <CAPTION style="display:none">Maps each kind of value to a mirrored * instance of a subinterface of Value</CAPTION> * <TR style="background-color:#EEEEFF"> * <TH id="primval" colspan=4>Subinterfaces of {@link PrimitiveValue}</TH> * <TR style="background-color:#EEEEFF"> * <TH id="kind" style="text-align:left">Kind of value</TH> * <TH id="example" style="text-align:left">For example -<br>expression in target</TH> * <TH id="mirrored" style="text-align:left">Is mirrored as an<br>instance of</TH> * <TH id="type" style="text-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}</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}</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'}</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}</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}</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}</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}</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}</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"> </TD> * <TD headers="primval mirrored"> {@link VoidValue}</TD> * <TD headers="primval type"> {@link VoidType}</TD> * <TR style="background-color:#EEEEFF"> * <TH id="objref" colspan=4>Subinterfaces of {@link ObjectReference}</TH> * <TR style="background-color:#EEEEFF"> * <TH id="kind2" style="text-align:left">Kind of value</TH> * <TH id="example2" style="text-align:left">For example -<br>expression in target</TH> * <TH id="mirrored2" style="text-align:left">Is mirrored as an<br>instance of</TH> * <TH id="type2" style="text-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}</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]}</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"}</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()}</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>&nbsp;&nbsp;{@code .getThreadGroup()}</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}<br>instance</TD> * <TD headers="objref example2"> {@code this.getClass()}</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>&nbsp;&nbsp;{@code .getClassLoader()}</TD> * <TD headers="objref mirrored2"> {@link ClassLoaderReference}</TD> * <TD headers="objref type2"> {@link ClassType}</TD> * <TR style="background-color:#EEEEFF"> * <TH id="other" colspan=4>Other</TH> * <TR style="background-color:#EEEEFF"> * <TD id="kind3" style="text-align:left">Kind of value</TD> * <TD id="example3" style="text-align:left">For example -<br>expression in target</TD> * <TD id="mirrored3" style="text-align:left">Is mirrored as</TD> * <TD id="type3" style="text-align:left">{@link Type} of value</TD> * <TR> * <TD headers="other kind3"> null</TD> * <TD headers="other example3"> {@code null}</TD> * <TD headers="other mirrored3"> {@code null}</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(); }