Java example source code file (Value.java)

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Java - Java tags/keywords

mirror, type, value

The Value.java Java example source code

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

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.
 * <P>
 * Some examples of where values may be accessed:
 * <BLOCKQUOTE>
 * <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>
 * <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}
 * <TR BGCOLOR="#EEEEFF">
 *   <TH id="kind"     align="left">Kind of value
 *   <TH id="example"  align="left">For example -
expression in target
 *   <TH id="mirrored" align="left">Is mirrored as an
instance of
 *   <TH id="type"     align="left">{@link Type} of value
{@link #type() Value.type()}
 * <TR>
 *   <TD headers="primval kind">     a boolean
 *   <TD headers="primval example">  true
 *   <TD headers="primval mirrored"> {@link BooleanValue}
 *   <TD headers="primval type">     {@link BooleanType}
 * <TR>
 *   <TD headers="primval kind">     a byte
 *   <TD headers="primval example">  (byte)4
 *   <TD headers="primval mirrored"> {@link ByteValue}
 *   <TD headers="primval type">     {@link ByteType}
 * <TR>
 *   <TD headers="primval kind">     a char
 *   <TD headers="primval example">  'a'
 *   <TD headers="primval mirrored"> {@link CharValue}
 *   <TD headers="primval type">     {@link CharType}
 * <TR>
 *   <TD headers="primval kind">     a double
 *   <TD headers="primval example">  3.1415926
 *   <TD headers="primval mirrored"> {@link DoubleValue}
 *   <TD headers="primval type">     {@link DoubleType}
 * <TR>
 *   <TD headers="primval kind">     a float
 *   <TD headers="primval example">  2.5f
 *   <TD headers="primval mirrored"> {@link FloatValue}
 *   <TD headers="primval type">     {@link FloatType}
 * <TR>
 *   <TD headers="primval kind">     an int
 *   <TD headers="primval example">  22
 *   <TD headers="primval mirrored"> {@link IntegerValue}
 *   <TD headers="primval type">     {@link IntegerType}
 * <TR>
 *   <TD headers="primval kind">     a long
 *   <TD headers="primval example">  1024L
 *   <TD headers="primval mirrored"> {@link LongValue}
 *   <TD headers="primval type">     {@link LongType}
 * <TR>
 *   <TD headers="primval kind">     a short
 *   <TD headers="primval example">  (short)12
 *   <TD headers="primval mirrored"> {@link ShortValue}
 *   <TD headers="primval type">     {@link ShortType}
 * <TR>
 *   <TD headers="primval kind">     a void
 *   <TD headers="primval example">   
 *   <TD headers="primval mirrored"> {@link VoidValue}
 *   <TD headers="primval type">     {@link VoidType}
 * <TR BGCOLOR="#EEEEFF">
 *   <TH id="objref" colspan=4>Subinterfaces of {@link ObjectReference}
 * <TR BGCOLOR="#EEEEFF">
 *   <TH id="kind2"     align="left">Kind of value
 *   <TH id="example2"  align="left">For example -
expression in target
 *   <TH id="mirrored2" align="left">Is mirrored as an
instance of
 *   <TH id="type2"     align="left">{@link Type} of value
{@link #type() Value.type()}
 * <TR>
 *   <TD headers="objref kind2">     a class instance
 *   <TD headers="objref example2">  this
 *   <TD headers="objref mirrored2"> {@link ObjectReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR>
 *   <TD headers="objref kind2">     an array
 *   <TD headers="objref example2">  new int[5]
 *   <TD headers="objref mirrored2"> {@link ArrayReference}
 *   <TD headers="objref type2">     {@link ArrayType}
 * <TR>
 *   <TD headers="objref kind2">     a string
 *   <TD headers="objref example2">  "hello"
 *   <TD headers="objref mirrored2"> {@link StringReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR>
 *   <TD headers="objref kind2">     a thread
 *   <TD headers="objref example2">  Thread.currentThread()
 *   <TD headers="objref mirrored2"> {@link ThreadReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR>
 *   <TD headers="objref kind2">     a thread group
 *   <TD headers="objref example2">  Thread.currentThread()
  .getThreadGroup()
 *   <TD headers="objref mirrored2"> {@link ThreadGroupReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR>
 *   <TD headers="objref kind2">     a java.lang.Class
instance
 *   <TD headers="objref example2">  this.getClass()
 *   <TD headers="objref mirrored2"> {@link ClassObjectReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR>
 *   <TD headers="objref kind2">     a class loader
 *   <TD headers="objref example2">  this.getClass()
  .getClassLoader() 
 *   <TD headers="objref mirrored2"> {@link ClassLoaderReference}
 *   <TD headers="objref type2">     {@link ClassType}
 * <TR BGCOLOR="#EEEEFF">
 *   <TH id="other" colspan=4>Other
 * <TR BGCOLOR="#EEEEFF">
 *   <TH id="kind3"     align="left">Kind of value
 *   <TH id="example3"  align="left">For example -
expression in target
 *   <TH id="mirrored3" align="left">Is mirrored as
 *   <TH id="type3"     align="left">{@link Type} of value
 * <TR>
 *   <TD headers="other kind3">     null
 *   <TD headers="other example3">  null
 *   <TD headers="other mirrored3"> null
 *   <TD headers="other type3">     n/a
 * </TABLE>
 *
 * @author Robert Field
 * @author Gordon Hirsch
 * @author James McIlree
 * @since  1.3
 */

@jdk.Exported
public interface Value extends Mirror {
    /**
     * 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();
}

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