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1   /*
2    * Copyright 2006-2013 the original author or authors.
3    *
4    * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
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.springframework.batch.core.job.flow.support.state;
17  
18  import java.util.Collection;
19  import java.util.Collections;
20  
21  import org.springframework.batch.core.job.flow.FlowExecution;
22  import org.springframework.batch.core.job.flow.FlowExecutionStatus;
23  
24  /**
25   * Implementation of the {@link FlowExecutionAggregator} interface that aggregates
26   * {@link FlowExecutionStatus}', using the status with the high precedence as the
27   * aggregate status.  See {@link FlowExecutionStatus} for details on status
28   * precedence.
29   *
30   * @author Dave Syer
31   * @since 2.0
32   */
33  public class MaxValueFlowExecutionAggregator implements FlowExecutionAggregator {
34  
35  	/**
36  	 * Aggregate all of the {@link FlowExecutionStatus}es of the
37  	 * {@link FlowExecution}s into one status. The aggregate status will be the
38  	 * status with the highest precedence.
39  	 *
40  	 * @see FlowExecutionAggregator#aggregate(Collection)
41  	 */
42  	@Override
43  	public FlowExecutionStatus aggregate(Collection<FlowExecution> executions) {
44  		if (executions == null || executions.size() == 0) {
45  			return FlowExecutionStatus.UNKNOWN;
46  		}
47  		return Collections.max(executions).getStatus();
48  	}
49  
50  }