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Jake Wharton2000b2f2019-12-11 20:37:49 -05001// Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file
2// for details. All rights reserved. Use of this source code is governed by a
3// BSD-style license that can be found in the LICENSE file.
4
5package backport;
6
7import java.util.Arrays;
8import java.util.HashSet;
9import java.util.List;
10import java.util.Set;
11
12public class SetBackportJava10Main {
13
14 public static void main(String[] args) {
15 testCopyOf();
16 }
17
18 private static void testCopyOf() {
19 Object anObject0 = new Object();
20 Object anObject1 = new Object();
21 List<Object> original = Arrays.asList(anObject0, anObject1);
22 Set<Object> copy = Set.copyOf(original);
23 assertEquals(2, copy.size());
24 assertEquals(new HashSet<>(original), copy);
25 assertTrue(copy.contains(anObject0));
26 assertTrue(copy.contains(anObject1));
27 assertMutationNotAllowed(copy);
28
29 // Mutate the original backing collection and ensure it's not reflected in copy.
30 Object newObject = new Object();
31 original.set(0, newObject);
32 assertFalse(copy.contains(newObject));
33
34 // Ensure duplicates are allowed and are de-duped.
35 assertEquals(Set.of(1, 2), Set.copyOf(List.of(1, 2, 1, 2)));
36
37 try {
38 Set.copyOf(null);
39 throw new AssertionError();
40 } catch (NullPointerException expected) {
41 }
42 try {
43 Set.copyOf(Arrays.asList(1, null, 2));
44 throw new AssertionError();
45 } catch (NullPointerException expected) {
46 }
47 }
48
49 private static void assertMutationNotAllowed(Set<Object> ofObject) {
50 try {
51 ofObject.add(new Object());
52 throw new AssertionError();
53 } catch (UnsupportedOperationException expected) {
54 }
55 }
56
57 private static void assertTrue(boolean value) {
58 if (!value) {
59 throw new AssertionError("Expected <true> but was <false>");
60 }
61 }
62
63 private static void assertFalse(boolean value) {
64 if (value) {
65 throw new AssertionError("Expected <false> but was <true>");
66 }
67 }
68
69 private static void assertEquals(Object expected, Object actual) {
70 if (expected != actual && !expected.equals(actual)) {
71 throw new AssertionError("Expected <" + expected + "> but was <" + actual + ">");
72 }
73 }
74}