我正在尝试用hadoop创建一个setwritable。这是我的实现。我刚开始使用mapreduce，我不知道该怎么做。我写了下面的代码，但它不工作。
自定义可写（需要是一个集合）：

public class TextPair implements Writable {

    private Text first;
    public HashSet<String> valueSet = new HashSet<String>();
    public TextPair() {

    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeInt(valueSet.size());
        Iterator<String> it = valueSet.iterator();
        while (it.hasNext()) {
            this.first = new Text(it.next());
            first.write(out);
        }
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        Iterator<String> it = valueSet.iterator();
        while (it.hasNext()) {
            this.first = new Text(it.next());
            first.readFields(in);
        }
    }

}

Map程序代码：

public class TokenizerMapper extends Mapper<Object, Text, Text, TextPair> {

    ArrayList<String> al = new ArrayList<String>();
    TextPair tp = new TextPair();

    public void map(Object key, Text value, Context context) throws IOException, InterruptedException {

        String [] val = value.toString().substring(2,value.toString().length()).split(" ");

        for(String v: val) {
            tp.valueSet.add(v);
        }
        String [] vals = value.toString().split(" ");

        for(int i=0; i<vals.length-1; i++) {
            setKey(vals[0],vals[i+1]);
            System.out.println(getKey());
            context.write(new Text(getKey()), tp); 
        }
    }

    public void setKey(String first,String second) {

        al.clear();
        al.add(first);
        al.add(second);

        java.util.Collections.sort(al);
    }

    public String getKey() {

        String tp = al.get(0)+al.get(1);
        return tp;
    }
 }

我基本上是想从Map器中发出一个setwritable as值。请建议我需要做什么改变。谢谢！