1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package libcore.util; 18 19 /** 20 * Converts integral types to strings. This class is public but hidden so that it can also be 21 * used by java.util.Formatter to speed up %d. This class is in java.lang so that it can take 22 * advantage of the package-private String constructor. 23 * 24 * The most important methods are appendInt/appendLong and intToString(int)/longToString(int). 25 * The former are used in the implementation of StringBuilder, StringBuffer, and Formatter, while 26 * the latter are used by Integer.toString and Long.toString. 27 * 28 * The append methods take AbstractStringBuilder rather than Appendable because the latter requires 29 * CharSequences, while we only have raw char[]s. Since much of the savings come from not creating 30 * any garbage, we can't afford temporary CharSequence instances. 31 * 32 * One day the performance advantage of the binary/hex/octal specializations will be small enough 33 * that we can lose the duplication, but until then this class offers the full set. 34 * 35 * @hide 36 */ 37 public final class IntegralToString { 38 /** 39 * The digits for every supported radix. 40 */ 41 private static final char[] DIGITS = { 42 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 43 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 44 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 45 'u', 'v', 'w', 'x', 'y', 'z' 46 }; 47 48 private static final char[] UPPER_CASE_DIGITS = { 49 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 50 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 51 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 52 'U', 'V', 'W', 'X', 'Y', 'Z' 53 }; 54 55 private IntegralToString() { 56 } 57 58 public static String bytesToHexString(byte[] bytes, boolean upperCase) { 59 char[] digits = upperCase ? UPPER_CASE_DIGITS : DIGITS; 60 char[] buf = new char[bytes.length * 2]; 61 int c = 0; 62 for (byte b : bytes) { 63 buf[c++] = digits[(b >> 4) & 0xf]; 64 buf[c++] = digits[b & 0xf]; 65 } 66 return new String(buf); 67 } 68 } 69
