Custom hash table based on customized array
/*
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Jakarta Element Construction Set",
* "Jakarta ECS" , and "Apache Software Foundation" must not be used
* to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* "Jakarta Element Construction Set" nor "Jakarta ECS" nor may "Apache"
* appear in their names without prior written permission of the Apache Group.
*
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
import java.util.Enumeration;
public class Hash implements java.io.Serializable {
private Array keys = new Array();
private Array elements = new Array();
public Hash() {
}
public void setSize(int newSize) {
keys.setSize(newSize);
elements.setSize(newSize);
}
public void setGrow(int growBy) {
keys.setGrow(growBy);
elements.setGrow(growBy);
}
public synchronized void put(String key, Object element) {
try {
if (containsKey(key)) {
elements.add(keys.location(key), element);
} else {
keys.add(key);
elements.add(element);
}
} catch (NoSuchObjectException nsoe) {
}
}
public synchronized void remove(String key) {
try {
if (containsKey(key)) {
elements.remove(keys.location(key));
elements.remove(elements.location(key));
}
} catch (NoSuchObjectException nsoe) {
}
}
public int size() {
return keys.getCurrentSize();
}
public boolean contains(Object element) {
try {
elements.location(element);
return (true);
} catch (NoSuchObjectException noSuchObject) {
return false;
}
}
public Enumeration keys() {
return keys;
}
public boolean containsKey(String key) {
try {
keys.location(key);
} catch (NoSuchObjectException noSuchObject) {
return false;
}
return (true);
}
public Enumeration elements() {
return elements;
}
public Object get(String key) {
try {
if (containsKey(key))
return (elements.get(keys.location(key)));
} catch (NoSuchObjectException nsoe) {
}
return null;
}
}
class Array implements java.util.Enumeration, java.io.Serializable {
private int current = 0;
private int size = 10;
private int grow = 2;
private int place = 0;
private Object[] elements = null;
private Object[] tmpElements = null;
public Array() {
init();
}
public Array(int size) {
setSize(size);
init();
}
public Array(int size, int grow) {
setSize(size);
setGrow(grow);
init();
}
private void init() {
elements = new Object[size];
}
public Object nextElement() throws java.util.NoSuchElementException {
if (elements[place] != null && place != current) {
place++;
return elements[place - 1];
} else {
place = 0;
throw new java.util.NoSuchElementException();
}
}
public boolean hasMoreElements() {
if (place < elements.length && current != place)
return true;
return false;
}
public void setSize(int size) {
this.size = size;
}
public int getCurrentSize() {
return current;
}
public void rehash() {
tmpElements = new Object[size];
int count = 0;
for (int x = 0; x < elements.length; x++) {
if (elements[x] != null) {
tmpElements[count] = elements[x];
count++;
}
}
elements = (Object[]) tmpElements.clone();
tmpElements = null;
current = count;
}
public void setGrow(int grow) {
this.grow = grow;
}
public void grow() {
size = size += (size / grow);
rehash();
}
public void add(Object o) {
if (current == elements.length)
grow();
try {
elements[current] = o;
current++;
} catch (java.lang.ArrayStoreException ase) {
}
}
public void add(int location, Object o) {
try {
elements[location] = o;
} catch (java.lang.ArrayStoreException ase) {
}
}
public void remove(int location) {
elements[location] = null;
}
public int location(Object o) throws NoSuchObjectException {
int loc = -1;
for (int x = 0; x < elements.length; x++) {
if ((elements[x] != null && elements[x] == o)
|| (elements[x] != null && elements[x].equals(o))) {
loc = x;
break;
}
}
if (loc == -1)
throw new NoSuchObjectException();
return (loc);
}
public Object get(int location) {
return elements[location];
}
public java.util.Enumeration elements() {
return this;
}
}
class NoSuchObjectException extends Exception {
public NoSuchObjectException() {
super("No such object found.");
}
}
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