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: Open Source License public class Main { public static String rightPad(String str, int size) { return rightPad(str, size, ' '); }// w w w . j av a 2s . c o m public static String rightPad(String str, int size, char padChar) { if (str == null) { return null; } else { int pads = size - str.length(); return pads <= 0 ? str : (pads > 8192 ? rightPad(str, size, String.valueOf(padChar)) : str.concat(repeat(padChar, pads))); } } public static String rightPad(String str, int size, String padStr) { if (str == null) { return null; } else { if (isEmpty(padStr)) { padStr = " "; } int padLen = padStr.length(); int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; } else if (padLen == 1 && pads <= 8192) { return rightPad(str, size, padStr.charAt(0)); } else if (pads == padLen) { return str.concat(padStr); } else if (pads < padLen) { return str.concat(padStr.substring(0, pads)); } else { 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)); } } } public static String repeat(String str, int repeat) { if (str == null) { return null; } else if (repeat <= 0) { return ""; } else { int inputLength = str.length(); if (repeat != 1 && inputLength != 0) { if (inputLength == 1 && repeat <= 8192) { return repeat(str.charAt(0), repeat); } else { int outputLength = inputLength * repeat; switch (inputLength) { case 1: return repeat(str.charAt(0), repeat); case 2: char ch0 = str.charAt(0); char ch1 = str.charAt(1); char[] output2 = new char[outputLength]; for (int buf = repeat * 2 - 2; buf >= 0; --buf) { output2[buf] = ch0; output2[buf + 1] = ch1; --buf; } return new String(output2); default: StringBuilder var9 = new StringBuilder(outputLength); for (int i = 0; i < repeat; ++i) { var9.append(str); } return var9.toString(); } } } else { return str; } } } public static String repeat(char ch, int repeat) { if (repeat <= 0) { return ""; } else { char[] buf = new char[repeat]; for (int i = repeat - 1; i >= 0; --i) { buf[i] = ch; } return new String(buf); } } public static boolean isEmpty(CharSequence cs) { return cs == null || cs.length() == 0; } }