StringExt


1   package org.incava.lang;
2   
3   import java.util.*;
4   
5   
6   /**
7    * Extensions to the String class.
8    */
9   public class StringExt
10  {
11      /**
12       * Set this to true for debugging output.
13       */
14      public static boolean DEBUG = false;
15  
16      /**
17       * Returns an array of strings split at the character delimiter.
18       */
19      public static String  [] split(String   str, char delim, int max) 
20      {
21          return split(str, "" + delim, max);
22      }
23  
24      /**
25       * Returns an array of strings split at the string delimiter.
26       */
27      public static String  [] split(String   str, String   delim, int max) 
28      {
29          if (max == 1) {
30              return new String  [] { str };
31          }
32          else {
33              --max;              // adjust count between 0 and 1
34              List splitList = new ArrayList();
35              int  nFound    = 0;
36              int  strlen    = str.length();
37              int  end       = 0;
38              int  beg       = 0;
39              int  delimlen  = delim.length();
40              for (int idx = 0; idx < strlen; ++idx) {
41                  if (left(str.substring(idx), delimlen).equals(delim)) {
42                      String   substr = str.substring(beg, end);
43                      splitList.add(substr);
44                      beg = end + 1;
45                      if (max > 0 && ++nFound >= max) {
46                          break;
47                      }
48                  }
49                  ++end;
50              }
51  
52              if (strlen > beg) {
53                  String   tmp = strlen == beg ? "" : str.substring(beg, strlen);
54                  splitList.add(tmp);
55              }
56  
57              if (DEBUG) {
58                  System.out.println("split(" + str + ", " + delim + ", " + max + "):");
59                  for (int i = 0; i < splitList.size(); ++i) {
60                      System.out.println("    [" + i + "] = '" + splitList.get(i) + "'");
61                  }
62              }
63              
64              return (String  [])splitList.toArray(new String  [0]);
65          }
66      }
67  
68      /**
69       * Returns an array of strings split at the character delimiter.
70       */
71      public static String  [] split(String   str, char delim) 
72      {
73          return split(str, "" + delim, -1);
74      }
75  
76      /**
77       * Returns an array of strings split at the string delimiter.
78       */
79      public static String  [] split(String   str, String   delim) 
80      {
81          return split(str, delim, -1);
82      }
83  
84      /**
85       * Converts the (possibly quoted) string into a list, delimited by
86       * whitespace and commas..
87       */
88      public static List listify(String   str)
89      {
90          // strip leading/trailing single/double quotes
91          if (str.charAt(0) == str.charAt(str.length() - 1) &&
92              (str.charAt(0) == '"' || str.charAt(0) == '\'')) {
93              str = str.substring(1, str.length() - 1);
94          }
95          
96          List list = new ArrayList();
97          StringTokenizer st = new StringTokenizer(str, " \t\n\r\f,");
98          while (st.hasMoreTokens()) {
99              String   tk = st.nextToken();
100             list.add(tk);
101         }
102         return list;
103     }
104 
105     /**
106      * Returns a string starting with the <code>str</code> parameter, with
107      * <code>ch</code>'s following the string to a length of
108      * <code>length</code>.
109      *
110      * Examples:
111      *     pad("abcd", '*', 8) -> "abcd****"
112      *     pad("abcd", '*', 3) -> "abcd"
113      */
114     public static String   pad(String   str, char ch, int length) 
115     {
116         StringBuffer   buf = new StringBuffer  (str);
117         while (buf.length() < length) {
118             buf.append(ch);
119         }
120         return buf.toString();
121     }
122 
123     /**
124      * Same as the <code>pad</code> method, but applies the padding to the
125      * left-hand (leading) side of the string.
126      *
127      * Examples:
128      * <pre>
129      *     pad("420", '*', 8) -> "*****420"
130      *     pad("1144", '*', 3) -> "1144"
131      * </pre>
132      */
133     public static String   padLeft(String   str, char ch, int length) 
134     {
135         return repeat(ch, length - str.length()) + str;
136     }
137 
138     public static String   pad(String   str, int length) 
139     {
140         return pad(str, ' ', length);
141     }
142 
143     public static String   repeat(String   str, int length) 
144     {
145         StringBuffer   buf = new StringBuffer  ();
146         for (int i = 0; i < length; ++i) {
147             buf.append(str);
148         }
149         return buf.toString();
150     }
151 
152     public static String   repeat(char ch, int length) 
153     {
154         StringBuffer   buf = new StringBuffer  ();
155         for (int i = 0; i < length; ++i) {
156             buf.append(ch);
157         }
158         return buf.toString();
159     }
160 
161     public String   toString(double n, int precision) 
162     {
163         String   str = Double.toString(n);
164         int    dot = str.indexOf('.');
165         if (dot != -1 && dot + precision < str.length()) {
166             str = str.substring(0, dot + precision);
167         }
168         return str;
169     }
170 
171     /**
172      * Returns the leftmost n characters of the string, not exceeding the length
173      * of the string. Does not throw the annoying IndexOutOfBoundsException.
174      */
175     public static String   left(String   str, int n) 
176     {
177         int x = Math.min(n, str.length());
178         x = Math.max(0, x);     // guard against 0
179         return str.substring(0, x);
180     }
181 
182     /**
183      * Returns the rightmost n characters of the string, not exceeding the
184      * length of the string. Does not throw the annoying
185      * IndexOutOfBoundsException.
186      */
187     public static String   right(String   str, int n) 
188     {
189         int x = Math.min(n, str.length());
190         x = Math.max(0, x);     // guard against 0
191         int s = str.length() - x;
192         return str.substring(s);
193     }
194 
195     public static String   join(Collection c, String   str)
196     {
197         StringBuffer   buf = new StringBuffer  ();
198         boolean isFirst = true;
199         Iterator it = c.iterator();
200         while (it.hasNext()) {
201             if (!isFirst) {
202                 buf.append(str);
203             }
204             else {
205                 isFirst = false;
206             }
207             buf.append(it.next());
208         }
209         return buf.toString();
210     }
211 
212     public static void test(String   str, char del) 
213     {
214         System.out.println("-----  test: \"" + str + "\"  -----");
215         String  [] splits = StringExt.split(str, del);
216         System.out.println("#splits: " + splits.length);
217         for (int i = 0; i < splits.length; ++i) {
218             System.out.println("    # " + i + ": " + splits[i]);
219         }
220     }
221 
222     public static void test(String   str, String   del) 
223     {
224         System.out.println("-----  test: \"" + str + "\"  -----");
225         String  [] splits = StringExt.split(str, del);
226         System.out.println("#splits: " + splits.length);
227         for (int i = 0; i < splits.length; ++i) {
228             System.out.println("    # " + i + ": " + splits[i]);
229         }
230     }
231 
232     public static void main(String  [] args) 
233     {
234         test("this;is;a;test", ';');
235         test(";is;a;test", ';');
236         test("this;is;a;", ';');
237         test("this;;a;test", ';');
238         test(";this;;a;test;;", ';');
239         test("this is yet another test, it is.", "is");
240     }
241 }
242 
243 
244
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