sequentialidgenerator.java

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/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 
package org.apache.commons.betwixt.io.id;


/** <p>Generates <code>ID</code>'s in numeric sequence.
  * A simple counter is used.
  * Every time that {@link #nextIdImpl} is called, 
  * this counter is incremented.</p>
  *
  * <p>By default, the counter starts at zero.
  * A user can set the initial value by using the 
  * {@link #SequentialIDGenerator(int start)} constructor.</p>
  *
  * @author <a href="mailto:[e-mail]">Robert Burrell Donkin</a>
  * @version $Revision: 1.7 $
  */
public final class SequentialIDGenerator extends AbstractIDGenerator {
    
    /** Counter used to assign <code>ID</code>'s */
    private int counter = 0;
        
    /** 
      * Base constructor.
      * Counter starts at zero.
      */
    public SequentialIDGenerator() {} 
    
    /** 
     * Constructor sets the start value for the counter.
     * 
     * <p><strong>Note</strong> since the counter increments
     * before returning the next value, 
     * first <code>ID</code> generated will be <em>one more</em>
     * than the given <code>start</code> parameter.</p>
     * 
     * @param start start the counting at this value
     */
    public SequentialIDGenerator(int start) {
        this.counter = start;
    }
    
    /** 
      * Increment counter and then return value.
      *
      * @return one more than the current counter (converted to a string)
      */
    public String nextIdImpl() {
        return Integer.toString(++counter);
    }
    
    /** 
      * Gets the current counter value 
      *
      * @return the last ID in the sequence
      */
    public int getCount() {
        return counter;
    }
}