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      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 {
     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      */
     27     public static boolean isEmpty(CharSequence str) {
     28         return (str == null || str.length() == 0);
     29     }
     30 
     31     /**
     32      * Returns true if a and b are equal, including if they are both null.
     33      * <p><i>Note: In platform versions 1.1 and earlier, this method only worked well if
     34      * both the arguments were instances of String.</i></p>
     35      * @param a first CharSequence to check
     36      * @param b second CharSequence to check
     37      * @return true if a and b are equal
     38      */
     39     public static boolean equals(CharSequence a, CharSequence b) {
     40         if (a == b) return true;
     41         int length;
     42         if (a != null && b != null && (length = a.length()) == b.length()) {
     43             if (a instanceof String && b instanceof String) {
     44                 return a.equals(b);
     45             }
     46             for (int i = 0; i < length; i++) {
     47                 if (a.charAt(i) != b.charAt(i)) return false;
     48             }
     49             return true;
     50         }
     51         return false;
     52     }
     53 
     54     /**
     55      * Returns list of multiple {@link CharSequence} joined into a single
     56      * {@link CharSequence} separated by localized delimiter such as ", ".
     57      *
     58      * @hide
     59      */
     60     public static CharSequence join(Iterable<CharSequence> list) {
     61         final CharSequence delimiter = ", ";
     62         return join(delimiter, list);
     63     }
     64 
     65     /**
     66      * Returns a string containing the tokens joined by delimiters.
     67      * @param tokens an array objects to be joined. Strings will be formed from
     68      *     the objects by calling object.toString().
     69      */
     70     public static String join(CharSequence delimiter, Object[] tokens) {
     71         StringBuilder sb = new StringBuilder();
     72         boolean firstTime = true;
     73         for (Object token: tokens) {
     74             if (firstTime) {
     75                 firstTime = false;
     76             } else {
     77                 sb.append(delimiter);
     78             }
     79             sb.append(token);
     80         }
     81         return sb.toString();
     82     }
     83 
     84     /**
     85      * Returns a string containing the tokens joined by delimiters.
     86      * @param tokens an array objects to be joined. Strings will be formed from
     87      *     the objects by calling object.toString().
     88      */
     89     public static String join(CharSequence delimiter, Iterable<?> tokens) {
     90         StringBuilder sb = new StringBuilder();
     91         boolean firstTime = true;
     92         for (Object token: tokens) {
     93             if (firstTime) {
     94                 firstTime = false;
     95             } else {
     96                 sb.append(delimiter);
     97             }
     98             sb.append(token);
     99         }
    100         return sb.toString();
    101     }
    102 
    103 }
    104