001 /* AccessibleValue.java -- aids in accessibly controlling values
002 Copyright (C) 2002, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
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013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
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019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
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031 independent module, the terms and conditions of the license of that
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033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package javax.accessibility;
040
041 /**
042 * If an object implements this interface then it must be able to control
043 * a numerical value. For example, a scroll bar has a position represented
044 * by a number. Accessibility software can use the implementations of this
045 * interface to change the associated value.
046 *
047 * <p>The <code>AccessibleContext.getAccessibleValue()</code> method should
048 * return <code>null</code> if an object does not implement this interface.
049 *
050 * @author Eric Blake (ebb9@email.byu.edu)
051 * @see Accessible
052 * @see AccessibleContext
053 * @see AccessibleContext#getAccessibleValue()
054 * @since 1.2
055 * @status updated to 1.4
056 */
057 public interface AccessibleValue
058 {
059 /**
060 * Gets the current value of this object, or null if it has not been set.
061 *
062 * @return the current value, or null
063 * @see #setCurrentAccessibleValue(Number)
064 */
065 Number getCurrentAccessibleValue();
066
067 /**
068 * Sets the current value of this object. Returns true if the number
069 * successfully changed.
070 *
071 * @param number the new value
072 * @return true on success
073 */
074 // XXX What happens if number is null?
075 boolean setCurrentAccessibleValue(Number number);
076
077 /**
078 * Gets the minimum value in the range of this object, or null if there is
079 * no minimum.
080 *
081 * @return the minimum
082 * @see #getMaximumAccessibleValue()
083 */
084 Number getMinimumAccessibleValue();
085
086 /**
087 * Gets the maximum value in the range of this object, or null if there is
088 * no maximum.
089 *
090 * @return the maximum
091 * @see #getMinimumAccessibleValue()
092 */
093 Number getMaximumAccessibleValue();
094 } // interface AccessibleValue