Java扫描仪而循环不会停止

Question

Im a first year CS student and I am working on an assignment but I ran into this while loop that won't stop...

import java.io.*;
import java.util.Scanner;

class Ass1{
public static void main(String[] args){
    int i=0;

    try{
        File myfile = new File ("./ages.txt");
        Scanner scanner = new Scanner(myfile);

        while(scanner.hasNext()){
            i++;
        }
        System.out.println("ages.txt contains " + i + " lines");
        scanner.close();
    }catch(IOException e){}
}
}

and the ages.txt file looks like the following (They are meant to be all in separate lines but somehow I can only show them in a line here :( )

200 201 202 203 205 205 207 208 210 213 214 217 218 219 219 221 225 226 227 227 231 232 238 238 240 309 313 314

I am trying to read all the lines from the text file and at the end print how many lines it contains.

Thank you in advance for your help.

Answer 1

You need to advance your scanner by calling scanner.next();

If you were counting lines, it would be better to use scanner.hasNextLine() and scanner.nextLine() respectively.

The way you have it written, scanner.hastNext() will always evaluate to true as the scanner has never actually left it's initial position, so there will always be a hasNext()

Answer 2

那是因为您没有在while循环内调用nextInt（）方法，这意味着扫描器永远不会前进到下一个标记。