Here you can find the source of blurKeepingExtension(String s)
public static String blurKeepingExtension(String s)
//package com.java2s; /*//from w w w . j av a2 s.com Copyright (C) 2012 The Stanford MobiSocial Laboratory Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ public class Main { public static boolean BLUR = true; /** blurs a filename but keeps the extension intact. * e.g. "secret.jpg" becomes "s....t.jpg" */ public static String blurKeepingExtension(String s) { if (s == null) return null; int idx = s.lastIndexOf("."); if (idx <= 0) return blur(s); // no extension int MAX_EXTENSION_LENGTH = 6; if (s.length() - idx > MAX_EXTENSION_LENGTH) return blur(s); // unusually long "extension", don't what's happening, play it safe by ignoring it // tail is everything from one char before the . till the end, String tail = s.substring(idx); // tail is [idx-1 to s.length] // blur the part before tail and append the rest to it. return blur(s.substring(0, idx)) + tail; } /** replaces everything but the first and last letter of the input string s by '.' * useful for bluring potentially sensitive information that is needed in log files * like email folder names * e.g. SECRET is returned as S....T */ public static String blur(String s) { if (!BLUR) return s; if (s == null || s.length() <= 1) return s; char c[] = s.toCharArray(); for (int i = 1; i < s.length() - 1; i++) c[i] = '.'; return new String(c); } }