org.jboss.util.Counter.java Source code

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Here is the source code for org.jboss.util.Counter.java

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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;
    }
}