如何在Java中同时读取多行作为输入

Question

I want to input a paragraph (multiple lines) at the same time (not one line by one line) in Java. I want to add "the line number is :" to each line I input in command prompt, and exit it when the input is null. The code below is my attempt.

I tried to research on Internet, but I am still confused with Scanner and BufferedReader.

How do I adjust my program?

import java.io.*;

public class Word {

    public static void main(String[] args) throws IOException{
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader input=new BufferedReader(is);
        String s=input.readLine();
        int lineNum=1;
        while(s!=null&&s.length()>0) {

            System.out.println("Line number "+lineNum+" : "+s);
            lineNum++;

        }
    }
}

Answer 1

In your code you cast the user input to variable "s" once before the loop. In the loop "s" never changes so there's no exit condition, and it will always print the exact same line. You have to put the line String s=input.readLine(); in the loop, so each time it will read a new line from the user.