System.out.println 同时打印

Question

我正在构建一个简单的程序，该程序使用 Ganymed for SSH2 库对 linux 服务器执行单个命令。这是我的代码...

public class Main {

static Scanner reader = new Scanner(System.in);


public static void main(String[] args) throws IOException, InterruptedException{        


    String hostname; // = "192.168.1.241";
    int port; // = 22
    String username; // = "root";
    String password; 
    String cmd; // = "echo 'Hello World'";

    //ask user for hostname/IP
    System.out.print("Enter hostname or IP: ");
    hostname = reader.nextLine();


    //ask user for port #
    System.out.print("Enter port number: ");
    port = reader.nextInt();        

        //create connection
        Connection connect = new Connection(hostname, port);

    //ask user for username
    System.out.println("Enter Username (best to use 'root'): ");
    username = reader.nextLine();

    //ask user for password
    System.out.println("Enter Password: ");
    password = reader.nextLine();   


    System.out.println("Attempting to log in...");

    reader.close(); 

        //establish connection
        connect.connect();

        //login using password
        connect.authenticateWithPassword(username, password);

        Thread.sleep(1000);
        if (Thread.interrupted())  // Clears interrupted status!
              throw new InterruptedException();

        Boolean didConnect = connect.isAuthenticationComplete();
        if (didConnect==false){
            throw new IOException("Authentication Unsucessful \nCheck hostname and port number, then try again.");
        }

            //open session
            Session session = connect.openSession();
            System.out.println("Opened session!");              




        System.out.println("Enter a command to execute: ");
        cmd = reader.nextLine();

        //execute command
        session.execCommand(cmd);


        //get output
        InputStream stdout = new StreamGobbler(session.getStdout());

        BufferedReader br = new BufferedReader(new InputStreamReader(stdout));

        String line = br.readLine();
        if (line!=null){
            System.out.println("Command sent succesfully!" + "\nOutput: " + "\n" + "\n" + line);
        }else{
            System.out.println("Command sent succesfully!" + "\nNo Output");
        }

        //close buffered reader
        br.close();

        //close session
        session.close();

        //close connection
        connect.close();


    }



}

不知为何……

//ask user for username
    System.out.println("Enter Username (best to use 'root'): ");
    username = reader.nextLine();

    //ask user for password
    System.out.println("Enter Password: ");
    password = reader.nextLine();   

同时打印，我不知道为什么！当使用 println 和使用 print 时，它还会在完全不同的行而不是紧挨着它的旁边获取用户输入。

我希望他们先询问用户名，然后询问密码，将用户输入放在输出旁边。但是，当我询问主机名和端口号时，它们会单独/按顺序打印，就像我想要的那样。我做错了什么？

Answer 1

在您执行port = reader.nextInt(); 之后，您需要放置一个reader.nextLine() 来读取具有int 的行的其余部分（和换行符）。

//ask user for port #
System.out.print("Enter port number: ");
port = reader.nextInt();        

reader.nextInt() 不会读取换行符或数字后的任何内容。

添加reader.nextLine()，然后其余代码如下：

reader.nextLine();

//ask user for username
System.out.println("Enter Username (best to use 'root'): ");
username = reader.nextLine();

//ask user for password
System.out.println("Enter Password: ");
password = reader.nextLine();

Answer 2

您的问题是您多次使用同一个 Scanner 对象来读取一行。它跳过了代码：

 //ask user for username
System.out.println("Enter Username (best to use 'root'): ");
username = reader.nextLine();

//ask user for password
System.out.println("Enter Password: ");
password = reader.nextLine();

因为对象已经为您正在调用的方法设置了值。

解决方法：每次使用时重新实例化对象：

reader = new Scanner(System.in);