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package com.sun.jdi;

import com.sun.jdi.event.ModificationWatchpointEvent;


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 tables illustrate 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 values



  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 role="presentation">
 * <TR>
 *   <TD>{@link ObjectReference#getValue(Field)
 *                 ObjectReference.getValue(Field)}
 *   <TD>- value of a field
 * <TR>
 *   <TD>{@link StackFrame#getValue(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 ModificationWatchpointEvent#valueToBe()
 *                 ModificationWatchpointEvent.valueToBe()}
 *   <TD>- returned with an event
 * </TABLE></BLOCKQUOTE>
 * <P>
 * The following tables illustrate which subinterfaces of Value
 * are used to mirror values in the target VM --
 * <TABLE class="plain">
 * <CAPTION>Subinterfaces of {@link PrimitiveValue}</CAPTION>
 * <THEAD style="background-color:#EEEEFF; text-align:left">
 * <TR>
 *   <TH scope="col" style="width:10em">Kind of value</TH>
 *   <TH scope="col" style="width:15em">For example -<br>expression in target</TH>
 *   <TH scope="col" style="width:15em">Is mirrored as an<br>instance of</TH>
 *   <TH scope="col" style="width:15em">{@link Type} of value<br>{@link #type() Value.type()}</TH>
 * </THEAD>
 * <TBODY style="text-align:left">
 * <TR>
 *   <TH scope="row">a boolean</TH>
 *   <TD>{@code true}</TD>
 *   <TD>{@link BooleanValue}</TD>
 *   <TD>{@link BooleanType}</TD>
 * <TR>
 *   <TH scope="row">a byte</TH>
 *   <TD>{@code (byte)4}</TD>
 *   <TD>{@link ByteValue}</TD>
 *   <TD>{@link ByteType}</TD>
 * <TR>
 *   <TH scope="row">a char</TH>
 *   <TD>{@code 'a'}</TD>
 *   <TD>{@link CharValue}</TD>
 *   <TD>{@link CharType}</TD>
 * <TR>
 *   <TH scope="row">a double</TH>
 *   <TD>{@code 3.1415926}</TD>
 *   <TD>{@link DoubleValue}</TD>
 *   <TD>{@link DoubleType}</TD>
 * <TR>
 *   <TH scope="row">a float</TH>
 *   <TD>{@code 2.5f}</TD>
 *   <TD>{@link FloatValue}</TD>
 *   <TD>{@link FloatType}</TD>
 * <TR>
 *   <TH scope="row">an int</TH>
 *   <TD>{@code 22}</TD>
 *   <TD>{@link IntegerValue}</TD>
 *   <TD>{@link IntegerType}</TD>
 * <TR>
 *   <TH scope="row">a long</TH>
 *   <TD>{@code 1024L}</TD>
 *   <TD>{@link LongValue}</TD>
 *   <TD>{@link LongType}</TD>
 * <TR>
 *   <TH scope="row">a short</TH>
 *   <TD>{@code (short)12}</TD>
 *   <TD>{@link ShortValue}</TD>
 *   <TD>{@link ShortType}</TD>
 * <TR>
 *   <TH scope="row">a void</TH>
 *   <TD></TD>
 *   <TD>{@link VoidValue}</TD>
 *   <TD>{@link VoidType}</TD>
 * </TBODY>
 * </TABLE>
 *
 * <TABLE class="plain">
 * <CAPTION>Subinterfaces of {@link ObjectReference}</CAPTION>
 * <THEAD style="background-color:#EEEEFF; text-align:left">
 * <TR>
 *   <TH scope="col" style="width:10em">Kind of value</TH>
 *   <TH scope="col" style="width:15em">For example -<br>expression in target</TH>
 *   <TH scope="col" style="width:15em">Is mirrored as an<br>instance of</TH>
 *   <TH scope="col" style="width:15em">{@link Type} of value<br>{@link #type() Value.type()}</TH>
 * </THEAD>
 * <TBODY style="text-align:left">
 * <TR>
 *   <TH scope="row">a class instance</TH>
 *   <TD>{@code this}</TD>
 *   <TD>{@link ObjectReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * <TR>
 *   <TH scope="row">an array</TH>
 *   <TD>{@code new int[5]}</TD>
 *   <TD>{@link ArrayReference}</TD>
 *   <TD>{@link ArrayType}</TD>
 * <TR>
 *   <TH scope="row">a string</TH>
 *   <TD>{@code "hello"}</TD>
 *   <TD>{@link StringReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * <TR>
 *   <TH scope="row">a thread</TH>
 *   <TD>{@code Thread.currentThread()}</TD>
 *   <TD>{@link ThreadReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * <TR>
 *   <TH scope="row">a thread group</TH>
 *   <TD>{@code Thread.currentThread()}<br>&nbsp;&nbsp;{@code .getThreadGroup()}</TD>
 *   <TD>{@link ThreadGroupReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * <TR>
 *   <TH scope="row">a {@code java.lang.Class}<br>instance</TH>
 *   <TD>{@code this.getClass()}</TD>
 *   <TD>{@link ClassObjectReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * <TR>
 *   <TH scope="row">a class loader</TH>
 *   <TD>{@code this.getClass()}<br>&nbsp;&nbsp;{@code .getClassLoader()}</TD>
 *   <TD>{@link ClassLoaderReference}</TD>
 *   <TD>{@link ClassType}</TD>
 * </TBODY>
 * </TABLE>
 *
 * <TABLE class="plain">
 * <CAPTION>Other values</CAPTION>
 * <THEAD style="background-color:#EEEEFF; text-align:left">
 * <TR>
 *   <TH scope="col" style="width:10em">Kind of value</TH>
 *   <TH scope="col" style="width:15em">For example -<br>expression in target</TH>
 *   <TH scope="col" style="width:15em">Is mirrored as</TH>
 *   <TH scope="col" style="width:15em">{@link Type} of value</TH>
 * </THEAD>
 * <TBODY style="text-align:left">
 * <TR>
 *   <TH scope="row">null</TH>
 *   <TD>{@code null}</TD>
 *   <TD>{@code null}</TD>
 *   <TD>n/a</TD>
 * </TBODY>
 * </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();
}