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23 
24 /* @test
25  * @bug 4546734 5007612
26  * @summary Test StringBuffer.trimToSize
27  * @key randomness
28  */
29 
30 package test.java.lang.StringBuffer;
31 
32 import java.util.Random;
33 import org.testng.annotations.Test;
34 
35 public class Trim {
36     private static Random generator = new Random();
37 
38     // Android-changed: Add @Test annotation and remove empty arguments.
39     // public static void main(String[] args) throws Exception {
40     @Test
main()41     public static void main() throws Exception {
42         bash();
43         //capacityCheck();
44     }
45 
46     // Make sure trimToSize is safe to use; it should never cause an
47     // exception or mutation
bash()48     private static void bash() throws Exception {
49         for (int i=0; i<1000; i++) {
50             StringBuffer sb1 = generateTestBuffer(0, 100);
51             StringBuffer sb2 = new StringBuffer(sb1);
52             sb1.trimToSize();
53             if (!sb1.toString().equals(sb2.toString()))
54                 throw new RuntimeException(
55                     "trim mutated stringbuffer contents");
56             // Append a random sb
57             StringBuffer sb3 = generateTestBuffer(0, 100);
58             sb1.append(sb3);
59             sb2.append(sb3);
60             if (generator.nextInt(2) == 0)
61                 sb1.trimToSize();
62             else
63                 sb2.trimToSize();
64             if (!sb1.toString().equals(sb2.toString()))
65                 throw new RuntimeException(
66                     "trim mutated stringbuffer contents");
67             // Append sb with lots of extra space
68             sb3 = new StringBuffer(100);
69             sb3.append("a");
70             sb1.append(sb3);
71             sb2.append(sb3);
72             if (generator.nextInt(2) == 0)
73                 sb1.trimToSize();
74             else
75                 sb2.trimToSize();
76             if (!sb1.toString().equals(sb2.toString()))
77                 throw new RuntimeException(
78                     "trim mutated stringbuffer contents");
79         }
80     }
81 
82     // This test gives some assurance that trimToSize is working but
83     // it should not be part of an automated run, and a failure here
84     // is not against spec; this method is provided simply to be run
85     // by hand and assure the engineer that it is working. The test
86     // may stop working at some time in the future depending on
87     // how String and StringBuffer are implemented because it depends
88     // upon the capacity method.
capacityCheck()89     private static void capacityCheck() {
90         for (int i=0; i<100; i++) {
91             int sizeNeeded = generator.nextInt(1000)+1;
92             int sizeExtra = generator.nextInt(100) + 1;
93             StringBuffer sb = new StringBuffer(sizeNeeded + sizeExtra);
94             StringBuffer sb2 = generateTestBuffer(sizeNeeded, sizeNeeded);
95             if (sb2.length() != sizeNeeded)
96                 throw new RuntimeException("sb generated incorrectly");
97             sb.append(sb2);
98             int oldCapacity = sb.capacity();
99             sb.trimToSize();
100             int newCapacity = sb.capacity();
101             if (oldCapacity == newCapacity)
102                 throw new RuntimeException("trim failed");
103         }
104     }
105 
getRandomIndex(int constraint1, int constraint2)106     private static int getRandomIndex(int constraint1, int constraint2) {
107         int range = constraint2 - constraint1;
108         if (range <= 0)
109             return constraint1;
110         int x = generator.nextInt(range);
111         return constraint1 + x;
112     }
113 
generateTestBuffer(int min, int max)114     private static StringBuffer generateTestBuffer(int min, int max) {
115         StringBuffer aNewStringBuffer = new StringBuffer();
116         int aNewLength = getRandomIndex(min, max);
117         for(int y=0; y<aNewLength; y++) {
118             int achar = generator.nextInt(30)+30;
119             char test = (char)(achar);
120             aNewStringBuffer.append(test);
121         }
122         return aNewStringBuffer;
123     }
124 
125 }
126