密码暗示提示

import java.io.BufferedReader;
import java.io.InputStreamReader;

class  passwordTest
{
	public static void main(String[] args) throws Exception
	{
		    String pwd = null;
			System.out.println("请输入您的密码:");
			pwd = getStr();
	}
	public static String getStr()throws Exception
	{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		Eraser es=new Eraser();
		Thread t=new Thread(es);
		t.start();
		Thread.yield();
		String str=br.readLine();
		return str;
	}
}
class Eraser implements Runnable
{
	boolean flag=true;
	public void run()
	{
	   while(flag)
		{
		   System.out.print("\b*");
		}
	}
};