我是hadoop新手。我有一个问题需要计算这些文件中特定数量字母的字数-例如，4个字母的字数，5个字母的字数等等。如果一个单词在课文中重复了20次，就要逐个数20次。我试过以下方法：
Map器类

public static class Map extends Mapper<LongWritable, Text, IntWritable, IntWritable> {
    final static IntWritable one = new IntWritable(1);
    IntWritable wordLength = new IntWritable();
    @Override
    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException
    {
        String line = value.toString();
        StringTokenizer tokenizer = new StringTokenizer(line);
        while (tokenizer.hasMoreTokens()) {
            wordLength.set(tokenizer.nextToken().length());
            context.write(wordLength, one);     
    }
    }
  }

减速器等级

public class Reduce extends Reducer<IntWritable, IntWritable, Text, IntWritable>{
    IntWritable tin = new IntWritable();
    IntWritable smal = new IntWritable();
    IntWritable bi = new IntWritable();
    int t, s, b;
    Text tiny = new Text("tiny");
    Text small = new Text("small");
    Text big = new Text("big");
    @Override
    public void reduce(IntWritable key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException{        
        for (IntWritable val:values){
            if(key.get() == 4){
                t += val.get();                         
                }
            else if(key.get()== 10){
                s += val.get();             
                }
            else if(10<=key.get()){
                b += val.get();             
                }
        }
        tin.set(t); 
        smal.set(s);
        bi.set(b);
        context.write(tiny, tin);
        context.write(small, smal);
        context.write(big, bi); 
    }
    }

在终端中运行时，我得到以下错误：error:java.io.ioexception:type mismatch in key from map:expected org.apache.hadoop.io.text，received org.apache.hadoop.io.intwriteable
我要做的是将键值对Map为，并减少它。这样我就可以得到长度为10,4的单词和长度最长的单词的输出。
我不确定我的方法是否正确，请求帮助解决