ImmutableUtils.java revision 22c3185bb7c8618437eabe6c597549e0989ec4e6 
1/*
2 * Copyright 2012, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32package org.jf.util;
33
34import com.google.common.collect.ImmutableList;
35import com.google.common.collect.ImmutableSet;
36import com.google.common.collect.ImmutableSortedSet;
37
38import javax.annotation.Nonnull;
39import javax.annotation.Nullable;
40
41public class ImmutableUtils {
42    @Nonnull public static <T> ImmutableList<T> nullToEmptyList(@Nullable ImmutableList<T> list) {
43        if (list == null) {
44            return ImmutableList.of();
45        }
46        return list;
47    }
48
49    @Nonnull public static <T> ImmutableSet<T> nullToEmptySet(@Nullable ImmutableSet<T> set) {
50        if (set == null) {
51            return ImmutableSet.of();
52        }
53        return set;
54    }
55
56    @Nonnull public static <T> ImmutableSortedSet<T> nullToEmptySortedSet(@Nullable ImmutableSortedSet<T> set) {
57        if (set == null) {
58            return ImmutableSortedSet.of();
59        }
60        return set;
61    }
62}
63