Here you can find the source of rightPad(String str, int size)
public static String rightPad(String str, int size)
//package com.java2s; //License from project: Apache License public class Main { private static final int PAD_LIMIT = 8192; public static String rightPad(String str, int size) { return rightPad(str, size, ' '); }// w w w. j a va 2s. c o m public static String rightPad(String str, int size, char padChar) { if (str == null) { return null; } int pads = size - str.length(); if (pads <= 0) { return str; } if (pads > PAD_LIMIT) { return rightPad(str, size, String.valueOf(padChar)); } return str.concat(padding(pads, padChar)); } public static String rightPad(String str, int size, String padStr) { if (str == null) { return null; } if (isEmpty(padStr)) { padStr = " "; } int padLen = padStr.length(); int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; } if ((padLen == 1) && (pads <= PAD_LIMIT)) { return rightPad(str, size, padStr.charAt(0)); } if (pads == padLen) { return str.concat(padStr); } if (pads < padLen) { return str.concat(padStr.substring(0, pads)); } char[] padding = new char[pads]; char[] padChars = padStr.toCharArray(); for (int i = 0; i < pads; i++) { padding[i] = padChars[(i % padLen)]; } return str.concat(new String(padding)); } private static String padding(int repeat, char padChar) throws IndexOutOfBoundsException { if (repeat < 0) { throw new IndexOutOfBoundsException("Cannot pad a negative amount: " + repeat); } char[] buf = new char[repeat]; for (int i = 0; i < buf.length; i++) { buf[i] = padChar; } return new String(buf); } public static boolean isEmpty(String str) { return (str == null) || (str.length() == 0); } public static String substring(String str, int start) { if (str == null) { return null; } if (start < 0) { start = str.length() + start; } if (start < 0) { start = 0; } if (start > str.length()) { return ""; } return str.substring(start); } public static String substring(String str, int start, int end) { if (str == null) { return null; } if (end < 0) { end = str.length() + end; } if (start < 0) { start = str.length() + start; } if (end > str.length()) { end = str.length(); } if (start > end) { return ""; } if (start < 0) { start = 0; } if (end < 0) { end = 0; } return str.substring(start, end); } }