Trim.java revision 2362:00cd9dc3c2b5 
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
29import java.util.Random;
30
31public 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}
119