Mega Code Archive
An integer synchronized counter class
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/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.util;
import java.io.Serializable;
/**
* An integer counter class.
*
* @version <tt>$Revision: 2800 $</tt>
* @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
*/
public class Counter
implements Serializable, Cloneable
{
/** The serialVersionUID */
private static final long serialVersionUID = 7736259185393081556L;
/** The current count */
private int count;
/**
* Construct a Counter with a starting value.
*
* @param count Starting value for counter.
*/
public Counter(final int count) {
this.count = count;
}
/**
* Construct a Counter.
*/
public Counter() {}
/**
* Increment the counter. (Optional operation)
*
* @return The incremented value of the counter.
*/
public int increment() {
return ++count;
}
/**
* Decrement the counter. (Optional operation)
*
* @return The decremented value of the counter.
*/
public int decrement() {
return --count;
}
/**
* Return the current value of the counter.
*
* @return The current value of the counter.
*/
public int getCount() {
return count;
}
/**
* Reset the counter to zero. (Optional operation)
*/
public void reset() {
this.count = 0;
}
/**
* Check if the given object is equal to this.
*
* @param obj Object to test equality with.
* @return True if object is equal to this.
*/
public boolean equals(final Object obj) {
if (obj == this) return true;
if (obj != null && obj.getClass() == getClass()) {
return ((Counter)obj).count == count;
}
return false;
}
/**
* Return a string representation of this.
*
* @return A string representation of this.
*/
public String toString() {
return String.valueOf(count);
}
/**
* Return a cloned copy of this object.
*
* @return A cloned copy of this object.
*/
public Object clone() {
try {
return super.clone();
}
catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/////////////////////////////////////////////////////////////////////////
// Wrappers //
/////////////////////////////////////////////////////////////////////////
/**
* Base wrapper class for other wrappers.
*/
private static class Wrapper
extends Counter
{
/** The serialVersionUID */
private static final long serialVersionUID = -1803971437884946242L;
/** The wrapped counter */
protected final Counter counter;
public Wrapper(final Counter counter) {
this.counter = counter;
}
public int increment() {
return counter.increment();
}
public int decrement() {
return counter.decrement();
}
public int getCount() {
return counter.getCount();
}
public void reset() {
counter.reset();
}
public boolean equals(final Object obj) {
return counter.equals(obj);
}
public String toString() {
return counter.toString();
}
public Object clone() {
return counter.clone();
}
}
/**
* Return a synchronized counter.
*
* @param counter Counter to synchronize.
* @return Synchronized counter.
*/
public static Counter makeSynchronized(final Counter counter) {
return new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = -6024309396861726945L;
public synchronized int increment() {
return this.counter.increment();
}
public synchronized int decrement() {
return this.counter.decrement();
}
public synchronized int getCount() {
return this.counter.getCount();
}
public synchronized void reset() {
this.counter.reset();
}
public synchronized int hashCode() {
return this.counter.hashCode();
}
public synchronized boolean equals(final Object obj) {
return this.counter.equals(obj);
}
public synchronized String toString() {
return this.counter.toString();
}
public synchronized Object clone() {
return this.counter.clone();
}
};
}
/**
* Returns a directional counter.
*
* @param counter Counter to make directional.
* @param increasing True to create an increasing only
* or false to create a decreasing only.
* @return A directional counter.
*/
public static Counter makeDirectional(final Counter counter,
final boolean increasing)
{
Counter temp;
if (increasing) {
temp = new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = 2161377898611431781L;
public int decrement() {
throw new UnsupportedOperationException();
}
public void reset() {
throw new UnsupportedOperationException();
}
};
}
else {
temp = new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = -4683457706354663230L;
public int increment() {
throw new UnsupportedOperationException();
}
};
}
return temp;
}
}
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