[출처]http://stackoverflow.com/questions/388461/how-can-i-pad-a-string-in-java
String phoneNumber = "4000";
String leftPadd = String.format("%-10s",
phoneNumber);
String rightPadd = String.format("%10s",
phoneNumber);
System.out.println(leftPadd);
System.out.println(rightPadAd);
Result:
4000
4000