import java.io.File;
import java.io.IOException;
import java.util.Scanner;

/**
   Reads a data set from a file. The file must have the format
   numberOfValues
   value1
   value2
   . . .
*/
public class DataSetReader {
    private double[] data;

    /**
      Reads a data set.
      @param filename the name of the file holding the data
      @return the data in the file
   */
    public double[] readFile(String filename) throws IOException {
        File inFile = new File(filename);
        Scanner in = new Scanner(inFile);
        try {
            readData( in );
            return data;
        } finally { in .close();
        }
    }

    /**
      Reads all data.
      @param in the scanner that scans the data
   */
    private void readData(Scanner in ) throws BadDataException {

        if (! in .hasNextInt()) {
            throw new BadDataException("Length expected");
        }
        int numberOfValues = in .nextInt();
        data = new double[numberOfValues];

        for (int i = 0; i < numberOfValues; i++) {
            readValue( in , i);
        }

        if ( in .hasNext()) {
            throw new BadDataException("End of file expected");
        }
    }

    /**
      Reads one data value.
      @param in the scanner that scans the data
      @param i the position of the value to read
   */
    private void readValue(Scanner in , int i) throws BadDataException {
        i = 0;
        while ( in .hasNextLine()) {
            i++;
        }

        if (i < 3) {
            throw new BadDataException("Too few data values given");
        } else if (i > 4) {
            throw new BadDataException("Too many data values given");
        }
        data[i] = in .nextDouble();
    }
}
Setting Validate Copy Format