import java.io.*;

import java.util.*;

/**

 * This class prompts the user for a password and attempts to mask input with "*"

 */

public class PasswordField {

  /**

   *@param input stream to be used (e.g. System.in)

   *@param prompt The prompt to display to the user.

   *@return The password as entered by the user.

   */

  public static final char[] getPassword(InputStream in, String prompt)

    throws IOException {

      MaskingThread maskingthread = new MaskingThread(prompt);

      Thread thread = new Thread(maskingthread);

      thread.start();

      char[] lineBuffer;

      char[] buf;

      int i;

      buf = lineBuffer = new char[128];

      int room = buf.length;

      int offset = 0;

      int c;

      loop:   while (true) {

         switch (c = in.read()) {

            case -1:

            case '\n':

               break loop;

            case '\r':

               int c2 = in.read();

               if ((c2 != '\n') && (c2 != -1)) {

                  if (!(in instanceof PushbackInputStream)) {

                     in = new PushbackInputStream(in);

                  }

                  ((PushbackInputStream)in).unread(c2);

                } else {

                  break loop;

                }

                default:

                   if (--room < 0) {

                      buf = new char[offset + 128];

                      room = buf.length - offset - 1;

                      System.arraycopy(lineBuffer, 0, buf, 0, offset);

                      Arrays.fill(lineBuffer, ' ');

                      lineBuffer = buf;

                   }

                   buf[offset++] = (char) c;

                   break;

         }

      }

      maskingthread.stopMasking();

      if (offset == 0) {

         return null;

      }

      char[] ret = new char[offset];

      System.arraycopy(buf, 0, ret, 0, offset);

      Arrays.fill(buf, ' ');

      return ret;

   }

}

import java.io.*;

public class PasswordApp {

   public static void main(String argv[]) {

      char password[] = null;

      try {

         password = PasswordField.getPassword(System.in, "Enter your password: ");

      } catch(IOException ioe) {

         ioe.printStackTrace();

      }

      if(password == null ) {

         System.out.println("No password entered");

      } else {

         System.out.println("The password entered is: "+String.valueOf(password));

      }

   }

}