用Java打印字符串变量

Question

I'm getting some weird output when running (seemingly simple) code. Here's what I have:

import java.util.Scanner;

public class TestApplication {
  public static void main(String[] args) {
    System.out.println("Enter a password: ");
    Scanner input = new Scanner(System.in);
    input.next();
    String s = input.toString();
    System.out.println(s);
  }
}

And the output I get after compiling successfully is:

Enter a password: 
hello
java.util.Scanner[delimiters=\p{javaWhitespace}+][position=5][match valid=true][need input=false][source closed=false][skipped=false][group separator=\,][decimal separator=\.][positive prefix=][negative prefix=\Q-\E][positive suffix=][negative suffix=][NaN string=\Q�\E][infinity string=\Q∞\E]

Which is sort of weird. What's happening and how do I print the value of s ?

Answer 1

You're getting the toString() value returned by the Scanner object itself which is not what you want and not how you use a Scanner object. What you want instead is the data obtained by the Scanner object. For example,

Scanner input = new Scanner(System.in);
String data = input.nextLine();
System.out.println(data);

Please read the tutorial on how to use it as it will explain all.

Edit
Please look here: Scanner tutorial

Also have a look at the Scanner API which will explain some of the finer points of Scanner's methods and properties.

Answer 2

You could also use BufferedReader :

import java.io.*;

public class TestApplication {
   public static void main (String[] args) {
      System.out.print("Enter a password: ");
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      String password = null;
      try {
         password = br.readLine();
      } catch (IOException e) {
         System.out.println("IO error trying to read your password!");
         System.exit(1);
      }
      System.out.println("Successfully read your password.");
   }
}

Answer 3

input.next();
String s = input.toString();

change it to

String s = input.next();

May be that's what you were trying to do.

Answer 4

This is more likely to get you what you want:

Scanner input = new Scanner(System.in);
String s = input.next();
System.out.println(s);

Answer 5

You are printing the wrong value. Instead if the string you print the scanners object. Try this

Scanner input = new Scanner(System.in);
String s = input.next();
System.out.println(s);

Answer 6

If you have tried all the other answers, and it still hasn't work, you can try skipping a line:

Scanner scan = new Scanner(System.in);
scan.nextLine();
String s = scan.nextLine();
System.out.println("String is " + s);