从1个文件中读取以生成2个文件

Question

I've been trying to do this problem for my schoolwork and for the life of me I cannot figure it out. The problem is: Write a program that reads in "worked_example_1/babynames.txt" and produces two files, boynames.txt and girlnames.txt, separating the data for the boys and girls.

This is the code from Worked Example 11 from wiley.com/go/javaexamples for this problem:

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

public class BabyNames
{
public static final double LIMIT = 50;

public static void main(String[] args) throws FileNotFoundException
{
    Scanner in = new Scanner(new File("babynames.txt"));

    RecordReader boys = new RecordReader(LIMIT);
    RecordReader girls = new RecordReader(LIMIT);

    while (boys.hasMore() || girls.hasMore())
    {
        int rank = in.nextInt();
        System.out.print(rank + " ");
        boys.process(in);
        girls.process(in);
        System.out.println();
    }

    in.close();
}
}

And this:

import java.util.Scanner;

public class RecordReader
{
private double total;
private double limit;

public RecordReader(double aLimit)
{
    total = 0;
    limit = aLimit;
}

public void process(Scanner in)
{
    String name = in.next();
    int count = in.nextInt();
    double percent = in.nextDouble();

    if (total < limit)
    {
        System.out.print(name + " ");
    }

    total = total + percent;
}

public boolean hasMore()
{
    return total < limit;
}
}

I created the babynames.txt and put in the same src folder as the .java file, it comes up with file not found, if I give the direct path to the file with

Scanner in = new Scanner(new File("C:/Users/me/SkyDrive/Schoolwork/CIS150AB/Chapter 11.1/src/babynames.txt"));

it finds the file but gives me this error:

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at BabyNames.main(BabyNames.java:20)

To me it looks like this error is because of Line 20 where int rank = in.nextInt(); and its looking for a string when its looking for an int, but this is directly from Wiley website so I am not sure.

Any help with this would be appreciated, apparently I am not meant for online classes for Java. Next class I am taking in school once there is one that works around my schedule.

Answer 1

If this is the format of your babynames.txt, this is what'll happen (I think, didn't try it).

• The scanner "in" reads the first int into "rank" (OK)
• Enter into boys.process()
  • "in" reads the first name (Jacob)
  • "in" tries to read the first int (1), but finds 1.0013, which is not an int

This scenario doesn't match your error (you'd get a stacktrace from RecordReader rather than from BabyNames) but maybe the line of thinking will work for you.

Try it with a debugger. If you can't, use in.next() rather than in.nextInt() or in.nextDouble(). You can than print the value and see why it's not what you think it is.

Your question actually raises two questions. The answer to the hidden one may be:

try (InputStream inputStream = BabyNames.class.getResourceAsStream("/babynames.txt");
     Scanner in = new Scanner(inputStream))
{
    // do stuff with in
}