Java扫描仪输入循环

Question

I've got a loop that is controlled by a variable called running which tells if the program is running or not. I am trying to achieve a loop that the user enters a command, and the program is answering him, but for some reason, It's seems like my String splits if its more than one word, this is what I have tried:

import java.util.Scanner;
public class ScannerTest{
    private boolean running = true;
    public ScannerTest(){
        Scanner s = new Scanner(System.in);
        while(running){
           String command = s.next();
           System.out.println(command);
        }
    }
}

If I am entering two or more words in the Scanner, It seems to split them.

Input  >> Hello what's your name?
Output >> Hello
       >> what's
       >> your
       >> name?

Maybe it's because of the While loop? How can i fix it? Thanks in advance.

Answer 1

Scanner#next() does just this -- it grabs the next token defined by any white-space delimiter(s), and does not get the next line. If your words have white space between them, it will grab the individual words one at a time with each invocation of the method.

Use Scanner#nextLine() instead if you want to grab the complete line that the user entered.

Edit: this question has to be a duplicate of another somewhere on this site.

Answer 2

next() method will split your input by space delimiter.

nextLine() method will fix your problem. nextLine(); will read the entire line at once.

Replace String command = s.next(); to String command = s.nextLine();

Answer 3

You're using

System.out.println();

just use

System.out.print();

only use println if you want the next output/input to be entered onto the next line.

Answer 4

为什么不使用end-of-file indicator ，您在解决方案中使用的循环称为sentinel-controlled repetition ，我认为使用end-of-file indicator来控制它的更好的价值是看我的答案java Scanner.hasNext（）的用法