import java.util.TimerTask;

import java.util.Timer;

public class BackAndForth2{

static enum Direction{

FORWARDS,BACKWORDS

}

public static void main(String[] args){

TimerTask task = new TimerTask(){

final static int MAXSTEPS = 20;

Direction direction = Direction.FORWARDS;

int steps = -1; // need print one more time for the first round.

boolean isInitial = true;

@Override

public void run(){

switch(direction){

case FORWARDS:

if(!isInitial)

System.out.print("\b "); // \b stands for backspace, just move the edit place back, no replacement

System.out.print("*");

break;

case BACKWORDS:

System.out.print("\b "); // replace current asterisk by space: back the index, use new character

System.out.print("\b\b*");

break;

}

if(++steps == MAXSTEPS){

direction = (direction == Direction.FORWARDS) ? Direction.BACKWORDS : Direction.FORWARDS;

steps = 0;

}

isInitial = false;

}

};

Timer timer = new Timer();

int interval = 1000;

if(args.length!=0){

try{

interval = Integer.parseInt(args[0]);

}catch(NumberFormatException nfe){

nfe.printStackTrace();

}

}

timer.schedule(task, 1000, interval);

}

}