SegmentCache.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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packagejavax.swing.text;

importjava.util.ArrayList;
importjava.util.Arrays;
importjava.util.List;

/**
 * SegmentCache caches <code>Segment</code>s to avoid continually creating
 * and destroying of <code>Segment</code>s. A common use of this class would
 * be:
 * <pre>
 * Segment segment = segmentCache.getSegment();
 * // do something with segment
 * ...
 * segmentCache.releaseSegment(segment);
 * </pre>
 *
 */
classSegmentCache {
/**
 * A global cache.
 */
privatestaticSegmentCachesharedCache = newSegmentCache();

/**
 * A list of the currently unused Segments.
 */
privateList<Segment> segments;


/**
 * Returns the shared SegmentCache.
 */
publicstaticSegmentCachegetSharedInstance() {
returnsharedCache;
 }

/**
 * A convenience method to get a Segment from the shared
 * <code>SegmentCache</code>.
 */
publicstaticSegmentgetSharedSegment() {
returngetSharedInstance().getSegment();
 }

/**
 * A convenience method to release a Segment to the shared
 * <code>SegmentCache</code>.
 */
publicstaticvoidreleaseSharedSegment(Segmentsegment) {
getSharedInstance().releaseSegment(segment);
 }



/**
 * Creates and returns a SegmentCache.
 */
publicSegmentCache() {
segments = newArrayList<Segment>(11);
 }

/**
 * Returns a <code>Segment</code>. When done, the <code>Segment</code>
 * should be recycled by invoking <code>releaseSegment</code>.
 */
publicSegmentgetSegment() {
synchronized(this) {
intsize = segments.size();

if (size > 0) {
returnsegments.remove(size - 1);
 }
 }
returnnewCachedSegment();
 }

/**
 * 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:
 * <pre>
 * segmentCache.releaseSegment(segment);
 * segmentCache.releaseSegment(segment);
 * </pre>
 * Will likely result in very bad things happening!
 */
publicvoidreleaseSegment(Segmentsegment) {
if (segmentinstanceofCachedSegment) {
synchronized(this) {
if (segment.copy) {
Arrays.fill(segment.array, '\u0000');
 }
segment.array = null;
segment.copy = false;
segment.count = 0;
segments.add(segment);
 }
 }
 }


/**
 * CachedSegment is used as a tagging interface to determine if
 * a Segment can successfully be shared.
 */
privatestaticclassCachedSegmentextendsSegment {
 }
}