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