Try this and see if it works:
public class MyObj implements WritableComparable<MyObj>{
    private String date;
    private Double name;
    public String getDate() { return date;}
    public Double getName() { return name;}
    @Override
    public void readFields(DataInput in) throws IOException {
        //Define how you want to read the fields
        }
    @Override
    public void writeFields(DataOutput out) throws IOException {
        //Define how you want to write the fields
    }
        .......
        .......
        .......
}