1 /* 2 * Copyright (C) 2013 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 android.text; 18 19 public class TextUtils { TextUtils()20 private TextUtils() { /* cannot be instantiated */ } 21 22 /** 23 * Returns true if the string is null or 0-length. 24 * @param str the string to be examined 25 * @return true if str is null or zero length 26 */ isEmpty(CharSequence str)27 public static boolean isEmpty(CharSequence str) { 28 if (str == null || str.length() == 0) 29 return true; 30 else 31 return false; 32 } 33 34 /** 35 * Returns true if a and b are equal, including if they are both null. 36 * <p><i>Note: In platform versions 1.1 and earlier, this method only worked well if 37 * both the arguments were instances of String.</i></p> 38 * @param a first CharSequence to check 39 * @param b second CharSequence to check 40 * @return true if a and b are equal 41 */ equals(CharSequence a, CharSequence b)42 public static boolean equals(CharSequence a, CharSequence b) { 43 if (a == b) return true; 44 int length; 45 if (a != null && b != null && (length = a.length()) == b.length()) { 46 if (a instanceof String && b instanceof String) { 47 return a.equals(b); 48 } else { 49 for (int i = 0; i < length; i++) { 50 if (a.charAt(i) != b.charAt(i)) return false; 51 } 52 return true; 53 } 54 } 55 return false; 56 } 57 58 /** 59 * Returns list of multiple {@link CharSequence} joined into a single 60 * {@link CharSequence} separated by localized delimiter such as ", ". 61 * 62 * @hide 63 */ join(Iterable<CharSequence> list)64 public static CharSequence join(Iterable<CharSequence> list) { 65 final CharSequence delimiter = ", "; 66 return join(delimiter, list); 67 } 68 69 /** 70 * Returns a string containing the tokens joined by delimiters. 71 * @param tokens an array objects to be joined. Strings will be formed from 72 * the objects by calling object.toString(). 73 */ join(CharSequence delimiter, Object[] tokens)74 public static String join(CharSequence delimiter, Object[] tokens) { 75 StringBuilder sb = new StringBuilder(); 76 boolean firstTime = true; 77 for (Object token: tokens) { 78 if (firstTime) { 79 firstTime = false; 80 } else { 81 sb.append(delimiter); 82 } 83 sb.append(token); 84 } 85 return sb.toString(); 86 } 87 88 /** 89 * Returns a string containing the tokens joined by delimiters. 90 * @param tokens an array objects to be joined. Strings will be formed from 91 * the objects by calling object.toString(). 92 */ join(CharSequence delimiter, Iterable tokens)93 public static String join(CharSequence delimiter, Iterable tokens) { 94 StringBuilder sb = new StringBuilder(); 95 boolean firstTime = true; 96 for (Object token: tokens) { 97 if (firstTime) { 98 firstTime = false; 99 } else { 100 sb.append(delimiter); 101 } 102 sb.append(token); 103 } 104 return sb.toString(); 105 } 106 107 } 108