JAVA中如何读取TXT文件数据并计算

import

import org.apache.
import org.apache.
import org.apache.
import org.apache.hadoop.mapreduce.Mapper;

public class MyMapper extends Mapper<LongWritable, Text, Text, DoubleWritable>{
    protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, DoubleWritable>.Context context)
            throws IOException, InterruptedException {
        String line = value.toString();
        String[] arra = line.split(",");
        double[] arrb = new double[arra.length-1];
        for(int i=0; i<arra.length-1; i++) {
            arrb[i] = Double.parseDouble(arra[i]);
        }
        Double a = arrb[0] - arrb[1];
        Double b = arrb[2] - arrb[3];
        Double c = Math.sqrt((Math.pow(a, 2) + Math.pow(b, 2)));
        
        context.write(new Text(arra[arra.length-1]), new DoubleWritable(c));
    }
}
如果有错误请求指正，谢谢。