是的，有可能。只需通过job.setnumreducetasks（1）将作业配置为使用单个减速机。这个简化程序将遍历所有键/值对。在 reduce() 方法只需在 cleanup() 方法输出最终结果。示例 (k, v) = (year, temperature) :

public class MaxTemperatureReducer extends Reducer<IntWritable, DoubleWritable, IntWritable, DoubleWritable> {
    private static int year = 0;
    private static double maxTemp = 0.0;

    @Override
    public void reduce(IntWritable key, Iterable<DoubleWritable> values, Context context) throws IOException, InterruptedException {
        for (DoubleWritable value : values) {
            if (value.get() > maxTemp) {
                year = key.get();
                maxTemp = value.get();
            }
        }
    }

    @Override
    public void cleanup(Context context) throws IOException, InterruptedException {
        context.write(new IntWritable(year), new DoubleWritable(maxTemp));
    }
}

简单的方法是简单地使用任意键（“月”）并在值中同时包含温度和日期-然后在reduce方法中，找到温度的最高值并返回日期和温度。