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1   /**
2    * Copyright 2010-2013 The Kuali Foundation
3    *
4    * Licensed under the Educational Community License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    * http://www.opensource.org/licenses/ecl2.php
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.kuali.common.util;
17  
18  public class Counter {
19  
20  	int count;
21  
22  	public Counter() {
23  		this(0);
24  	}
25  
26  	public Counter(int startValue) {
27  		this.count = startValue;
28  	}
29  
30  	public synchronized int increment() {
31  		return increment(1);
32  	}
33  
34  	public synchronized int increment(int amount) {
35  		Assert.isTrue(amount > 0, "amount must be > 0");
36  		Assert.isTrue(count <= Integer.MAX_VALUE - amount, "max value exceeded");
37  		return count += amount;
38  	}
39  
40  	public synchronized int decrement() {
41  		return decrement(1);
42  	}
43  
44  	public synchronized int decrement(int amount) {
45  		Assert.isTrue(amount > 0, "amount must be > 0");
46  		Assert.isTrue(count >= Integer.MIN_VALUE + amount, "min value exceeded");
47  		return count -= amount;
48  	}
49  
50  	public synchronized int getValue() {
51  		return count;
52  	}
53  }