|
1
55
56 package org.apache.bsf.debug.util;
57
58 import java.util.Enumeration  ;
59 import java.util.NoSuchElementException ;
60
76
77 public class IntHashtable implements Cloneable {
78
79 int elementCount;
80 IntHashMapEntry[] elementData;
81 private int loadFactor;
82 private int threshold;
83
84 private static final class HashEnumerator implements Enumeration {
85 IntHashMapEntry array[];
86 int start, end;
87 IntHashMapEntry entry;
88 HashEnumerator (IntHashMapEntry[] entries) {
89 array = entries;
90 start = 0;
91 end = array.length;
92 }
93 public boolean hasMoreElements () {
94 if (entry != null) return true;
95 while (start < end) {
96 if (array[start] == null) start++;
97 else return true;
98 }
99 return false;
100 }
101 public Object nextElement () {
102 if (hasMoreElements()) {
103 if (entry == null) entry = array[start++];
104 Object result = entry.value;
105 entry = entry.next;
106 return result;
107 }
108 throw new NoSuchElementException ();
109 }
110 }
111
112
119 public IntHashtable() {
120 this (101);
121 }
122
131 public IntHashtable(int capacity) {
132 if (capacity < 0) throw new IllegalArgumentException ();
133 elementCount = 0;
134 elementData = new IntHashMapEntry[capacity == 0 ? 1 : capacity];
135 loadFactor = 7500; computeMaxSize();
137 }
138
148 public IntHashtable(int capacity, float loadFactor) {
149 if (capacity < 0 || loadFactor <= 0)
150 throw new IllegalArgumentException ();
151 elementCount = 0;
152 elementData = new IntHashMapEntry[capacity];
153 this.loadFactor = (int)(loadFactor * 10000);
154 computeMaxSize();
155 }
156
166 public synchronized void clear() {
167 elementCount = 0;
168 for (int i = elementData.length; --i >= 0;) {
169 elementData[i] = null;
170 }
171 }
172
183 public synchronized Object clone() {
184 try {
185 IntHashtable hashtable = (IntHashtable) super.clone ();
186 hashtable.elementData = (IntHashMapEntry[])elementData.clone();
187 IntHashMapEntry entry;
188 for (int i=elementData.length; --i >= 0;) {
189 if ((entry = elementData[i]) != null)
190 hashtable.elementData[i] = (IntHashMapEntry)entry.clone();
191 }
192 return hashtable;
193 } catch (CloneNotSupportedException e) {
194 return null;
195 }
196 }
197 private void computeMaxSize() {
198 threshold = (int)((long)elementData.length * loadFactor / 10000);
199 }
200
213 public synchronized boolean contains(Object value) {
214 for (int i=elementData.length; --i >= 0;) {
215 IntHashMapEntry entry = elementData[i];
216 while (entry != null) {
217 if (entry.value == value || entry.value.equals(value))
218 return true;
219 entry = entry.next;
220 }
221 }
222 return false;
223 }
224
237 public synchronized boolean containsKey(int key) {
238 return getEntry(key) != null;
239 }
240
254 public synchronized Enumeration elements() {
255 return new HashEnumerator (elementData);
256 }
257
270 public synchronized Object get(int key) {
271 int index = (key & 0x7FFFFFFF) % elementData.length;
272 IntHashMapEntry entry = elementData[index];
273 while (entry != null) {
274 if (entry.key == key) return entry.value;
275 entry = entry.next;
276 }
277 return null;
278 }
279 private IntHashMapEntry getEntry(int key) {
280 int index = (key & 0x7FFFFFFF) % elementData.length;
281 IntHashMapEntry entry = elementData[index];
282 while (entry != null) {
283 if (entry.key == key) return entry;
284 entry = entry.next;
285 }
286 return null;
287 }
288
298 public boolean isEmpty() {
299 return elementCount == 0;
300 }
301
319 public synchronized Object put(int key, Object value) {
320 if (value == null) throw new NullPointerException ();
321 int index = (key & 0x7FFFFFFF) % elementData.length;
322 IntHashMapEntry entry = elementData[index];
323 while (entry != null) {
324 if (entry.key == key) break;
325 entry = entry.next;
326 }
327 if (entry == null) {
328 if (++elementCount > threshold) {
329 rehash();
330 index = (key & 0x7FFFFFFF) % elementData.length;
331 }
332 entry = new IntHashMapEntry(key, value);
333 entry.next = elementData[index];
334 elementData[index] = entry;
335 return null;
336 }
337 Object result = entry.value;
338 entry.value = value;
339 return result;
340 }
341
348 protected void rehash() {
349 int length = elementData.length<<1;
350 if (length == 0) length = 1;
351 IntHashMapEntry[] newData = new IntHashMapEntry[length];
352 for (int i=elementData.length; --i >= 0;) {
353 IntHashMapEntry entry = elementData[i];
354 while (entry != null) {
355 int index = (entry.key & 0x7FFFFFFF) % length;
356 IntHashMapEntry next = entry.next;
357 entry.next = newData[index];
358 newData[index] = entry;
359 entry = next;
360 }
361 }
362 elementData = newData;
363 computeMaxSize();
364 }
365
378 public synchronized Object remove(int key) {
379 IntHashMapEntry last = null;
380 int index = (key & 0x7FFFFFFF) % elementData.length;
381 IntHashMapEntry entry = elementData[index];
382 while (entry != null) {
383 if (entry.key == key) break;
384 last = entry;
385 entry = entry.next;
386 }
387 if (entry != null) {
388 if (last == null) elementData[index] = entry.next;
389 else last.next = entry.next;
390 elementCount--;
391 return entry.value;
392 }
393 return null;
394 }
395
406 public int size() {
407 return elementCount;
408 }
409
417 public synchronized String toString() {
418 Object key;
419 int count = 0;
420 StringBuffer buffer = new StringBuffer ();
421 buffer.append ('{');
422 for (int i=elementData.length; --i >= 0;) {
423 IntHashMapEntry entry = elementData[i];
424 while (entry != null) {
425 buffer.append(entry.key);
426 buffer.append('=');
427 buffer.append(entry.value);
428 buffer.append(',');
429 entry = entry.next;
430 }
431 }
432 if (elementCount > 0) buffer.setLength(buffer.length() - 1);
434 buffer.append ('}');
435 return buffer.toString ();
436 }
437 }
438 |
Popular Tags |
Java API By Example, From Geeks To Geeks.