如何保持Java程序运行（循环），以便可以使用扫描仪输入相同的文本文件？

Question

I am trying to use the java scanner input to read multiple inputs (numbers as a string eg. 12345) from keyboard and send to a text file, I have a scanner reading input.nextLine(), where it will read in each line. I just would like to run my program and have it stay running so it will populate the text file with each scanner input. I am using the following code:

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

public class tap1 
{    
    public static void main(String[] args) throws IOException
    {
        System.out.println("Please enter number:");     
        File outFile = new File ("CardNumbers.txt");
        FileWriter fWriter = new FileWriter (outFile, true);
        PrintWriter pWriter = new PrintWriter (fWriter);
        Scanner scan = new Scanner(System.in);
        String num = scan.nextLine();
        pWriter.println (num);
        pWriter.close();                
    }   
}

Answer 1

You can wrap it in a loop like

  while(scanner.hasNext){
    scanner.nextLine();
  //Do some code
}

You'll keep "scanning" for new input until EOF is reached and untill then your program keep running.

Answer 2

You can try this

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

public class tap1 
{    
    public static void main(String[] args) throws IOException
    {
        System.out.println("Please enter number:");     
        File outFile = new File ("CardNumbers.txt");
        FileWriter fWriter = new FileWriter (outFile, true);
        PrintWriter pWriter = new PrintWriter (fWriter);
        Scanner scan = new Scanner(System.in);
        String num = "";
        while(true){
        num=scan.nextLine();
        if(num.equals("exit")){
           break;
        }
        pWriter.println (num);
        }
        pWriter.close();                
    }   
}