content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 com.aliyun.odps.mapred.example.local.lib.aggregate;
  
  import java.util.ArrayList;
  
  /**
   * This class implements a value aggregator that maintain the biggest of a
   * sequence of strings.
   */
  public class StringValueMax implements ValueAggregator {
  
    String maxVal = null;
  
    /**
     * the default constructor
     */
    public StringValueMax() {
      reset();
    }
  
    /**
     * add a value to the aggregator
     *
     * @param val
     *     a string.
     */
    public void addNextValue(Object val) {
      String newVal = val.toString();
      if (this.maxVal == null || this.maxVal.compareTo(newVal) < 0) {
        this.maxVal = newVal;
      }
    }
  
    /**
     * @return the aggregated value
     */
    public String getVal() {
      return this.maxVal;
    }
  
    /**
     * @return the string representation of the aggregated value
     */
    public String getReport() {
      return maxVal;
    }
  
    /**
     * reset the aggregator
     */
    public void reset() {
      maxVal = null;
    }
  
    /**
     * @return return an array of one element. The element is a string
     * representation of the aggregated value. The return value is
     * expected to be used by the a combiner.
     */
    public ArrayList<String> getCombinerOutput() {
      ArrayList<String> retv = new ArrayList<String>(1);
      retv.add(maxVal);
      return retv;
    }
  }
  