/*
* @(#)SegmentCache.java 1.5 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.text;
import java.util.ArrayList;
import java.util.List;
/**
* SegmentCache caches Segment
s to avoid continually creating
* and destroying of Segment
s. A common use of this class would
* be:
*
* Segment segment = segmentCache.getSegment(); * // do something with segment * ... * segmentCache.releaseSegment(segment); ** * @version 1.5 12/19/03 */ class SegmentCache { /** * A global cache. */ private static SegmentCache sharedCache = new SegmentCache(); /** * A list of the currently unused Segments. */ private List segments; /** * Returns the shared SegmentCache. */ public static SegmentCache getSharedInstance() { return sharedCache; } /** * A convenience method to get a Segment from the shared *
SegmentCache
.
*/
public static Segment getSharedSegment() {
return getSharedInstance().getSegment();
}
/**
* A convenience method to release a Segment to the shared
* SegmentCache
.
*/
public static void releaseSharedSegment(Segment segment) {
getSharedInstance().releaseSegment(segment);
}
/**
* Creates and returns a SegmentCache.
*/
public SegmentCache() {
segments = new ArrayList(11);
}
/**
* Returns a Segment
. When done, the Segment
* should be recycled by invoking releaseSegment
.
*/
public Segment getSegment() {
synchronized(this) {
int size = segments.size();
if (size > 0) {
return (Segment)segments.remove(size - 1);
}
}
return new CachedSegment();
}
/**
* Releases a Segment. You should not use a Segment after you release it,
* and you should NEVER release the same Segment more than once, eg:
* * segmentCache.releaseSegment(segment); * segmentCache.releaseSegment(segment); ** Will likely result in very bad things happening! */ public void releaseSegment(Segment segment) { if (segment instanceof CachedSegment) { synchronized(this) { segment.array = null; segment.count = 0; segments.add(segment); } } } /** * CachedSegment is used as a tagging interface to determine if * a Segment can successfully be shared. */ private static class CachedSegment extends Segment { } }