Max与Min

MaxAggregate 实现最大值聚合，而 MinAggregate 实现最小值聚合。

类定义

    public static class MaxAggregate implements Aggregate<Comparable>
    {
        public void initialize(Comparable val) 
        {
            max = val;
        }
 
        public void accumulate(Comparable val) 
        {
            if (val.compareTo(max) > 0) 
            {
                max = val;
            }
        }
 
        public Object result() 
        {
            return max;
        }
 
        public void merge(Aggregate<Comparable> other) 
        {
            accumulate((Comparable)other.result());
        }
 
        Comparable max;
        
    }

MinAggregate

MinAggregate 的实现与 MaxAggregate 完全相同，只是变量名是 min 而不是 max（如下突出显示），并且 compareTo() 表达式是

    if (val.compareTo(min) < 0)

而不是

    if (val.compareTo(max) > 0)