请问下面这个报错怎么解决java.io.IOException

请问下面这个报错怎么解决

public static class Map extends Mapper<LongWritable, Text, Text, Text>

public static class Combine extends Reducer<Text, Text, Text, MapWritable>

public static class Reduce extends Reducer<Text, MapWritable, Text, IntWritable>

这样写三个函数，map运行了一部分之后就报错 说class org.apache.hadoop.io.MapWritable is not class org.apache.hadoop.io.Text

java.io.IOException: Cannot create an instance of InputFormat class org.apache.hadoop.mapred.TextInputFormat as specified in mapredWork!

明显的类型不匹配啊