mapreduce排序中java.io.IOException: Illegal partition for 2 (-1)

mapreduce程序，自定义了Partition，运行时出现以下异常：

java.io.IOException: Illegal partition for 2 (-1)

 

自定义Partition代码：

public static class Partition extends Partitioner<IntWritable,IntWritable>
{
@Override
public int getPartition(IntWritable key, IntWritable value, int numPartitions) 
 {
int Maxnumber = 65223;
int bound = Maxnumber/numPartitions+1;
int keynumber = key.get();
for (int i = 0; i < numPartitions; i++) {
if(keynumber<bound*i&&keynumber>=bound*(i-1))
{
return i-1;
}
}
return -1;
}

}

 

原因：

出现错误的原因是在某种情况下getPartition函数返回了-1，Partition是从0开始的，默认返回-1是不正确的。

解决方法：

默认返回0

public static class Partition extends Partitioner<IntWritable,IntWritable>
{
@Override
public int getPartition(IntWritable key, IntWritable value, int numPartitions) 
 {
int Maxnumber = 65223;
int bound = Maxnumber/numPartitions+1;
int keynumber = key.get();
for (int i = 0; i < numPartitions; i++) {
if(keynumber<bound*i&&keynumber>=bound*(i-1))
{
return i-1;
}
}
return 0;
}

}