SecondarySort-OverrideError(删除注释)

Question

它在eclipse中指出的错误是我必须删除注释覆盖。尽管我试图删除注释，但再次出现错误，它表明该方法必须重新实现

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package com.secondarysort;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableUtils;
/**
 * @author mrinmoy
 *
 */
public class CompositeKey implements WritableComparable
{
    public String Text;
    public String count;
    public CompositeKey (String Text,String count)
    {
        this.Text=Text;
        this.count=count;
    }
    public CompositeKey() {
        // TODO Auto-generated constructor stub
    }
    public String getText() {
        return Text;
    }
    public void setText(String text) {
        Text = text;
    }
    public String getCount() {
        return count;
    }
    public void setCount(String count) {
        this.count = count;
    }

    public String toString()
    {
        return (new StringBuilder()).append(Text).append(',').append(count).toString();
    }

    @Override
    public void readFields(DataInput arg0) throws IOException {
        // TODO Auto-generated method stub
        Text = WritableUtils.readString(arg0);
        count=WritableUtils.readString(arg0);
    }
    @Override
    public void write(DataOutput arg0) throws IOException {
        // TODO Auto-generated method stub
        WritableUtils.writeString(arg0,Text);
        WritableUtils.writeString(arg0, count);
    }
    @Override
    public int compareTo(CompositeKey com) {
        // TODO Auto-generated method stub
        int result=Text.compareTo(com.Text);
        if(0==result)
        {
            result=count.compareTo(com.count);
        }
        return result;
    }

}

Answer 1

您需要指定要重写的WritableComparable的泛型类型，否则将无法正确重写compareTo。这是因为编译器没有用泛型代替Object，所以只使用CompositeKey s的compareTo不会覆盖它

public class CompositeKey implements WritableComparable<CompositeKey> {
    // ...
}