1 /*
   2  * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /* @test
  25  * @bug 4546734 5007612
  26  * @summary Test StringBuffer.trimToSize
  27  */
  28 
  29 import java.util.Random;
  30 
  31 public class Trim {
  32     private static Random generator = new Random();
  33 
  34     public static void main(String[] args) throws Exception {
  35         bash();
  36         //capacityCheck();
  37     }
  38 
  39     // Make sure trimToSize is safe to use; it should never cause an
  40     // exception or mutation
  41     private static void bash() throws Exception {
  42         for (int i=0; i<1000; i++) {
  43             StringBuffer sb1 = generateTestBuffer(0, 100);
  44             StringBuffer sb2 = new StringBuffer(sb1);
  45             sb1.trimToSize();
  46             if (!sb1.toString().equals(sb2.toString()))
  47                 throw new RuntimeException(
  48                     "trim mutated stringbuffer contents");
  49             // Append a random sb
  50             StringBuffer sb3 = generateTestBuffer(0, 100);
  51             sb1.append(sb3);
  52             sb2.append(sb3);
  53             if (generator.nextInt(2) == 0)
  54                 sb1.trimToSize();
  55             else
  56                 sb2.trimToSize();
  57             if (!sb1.toString().equals(sb2.toString()))
  58                 throw new RuntimeException(
  59                     "trim mutated stringbuffer contents");
  60             // Append sb with lots of extra space
  61             sb3 = new StringBuffer(100);
  62             sb3.append("a");
  63             sb1.append(sb3);
  64             sb2.append(sb3);
  65             if (generator.nextInt(2) == 0)
  66                 sb1.trimToSize();
  67             else
  68                 sb2.trimToSize();
  69             if (!sb1.toString().equals(sb2.toString()))
  70                 throw new RuntimeException(
  71                     "trim mutated stringbuffer contents");
  72         }
  73     }
  74 
  75     // This test gives some assurance that trimToSize is working but
  76     // it should not be part of an automated run, and a failure here
  77     // is not against spec; this method is provided simply to be run
  78     // by hand and assure the engineer that it is working. The test
  79     // may stop working at some time in the future depending on
  80     // how String and StringBuffer are implemented because it depends
  81     // upon the capacity method.
  82     private static void capacityCheck() {
  83         for (int i=0; i<100; i++) {
  84             int sizeNeeded = generator.nextInt(1000)+1;
  85             int sizeExtra = generator.nextInt(100) + 1;
  86             StringBuffer sb = new StringBuffer(sizeNeeded + sizeExtra);
  87             StringBuffer sb2 = generateTestBuffer(sizeNeeded, sizeNeeded);
  88             if (sb2.length() != sizeNeeded)
  89                 throw new RuntimeException("sb generated incorrectly");
  90             sb.append(sb2);
  91             int oldCapacity = sb.capacity();
  92             sb.trimToSize();
  93             int newCapacity = sb.capacity();
  94             if (oldCapacity == newCapacity)
  95                 throw new RuntimeException("trim failed");
  96         }
  97     }
  98 
  99     private static int getRandomIndex(int constraint1, int constraint2) {
 100         int range = constraint2 - constraint1;
 101         if (range <= 0)
 102             return constraint1;
 103         int x = generator.nextInt(range);
 104         return constraint1 + x;
 105     }
 106 
 107     private static StringBuffer generateTestBuffer(int min, int max) {
 108         StringBuffer aNewStringBuffer = new StringBuffer();
 109         int aNewLength = getRandomIndex(min, max);
 110         for(int y=0; y<aNewLength; y++) {
 111             int achar = generator.nextInt(30)+30;
 112             char test = (char)(achar);
 113             aNewStringBuffer.append(test);
 114         }
 115         return aNewStringBuffer;
 116     }
 117 
 118 }