9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import jdk.internal.misc.CDS;
29 import jdk.internal.misc.VM;
30 import jdk.internal.util.DecimalDigits;
31 import jdk.internal.vm.annotation.AOTRuntimeSetup;
32 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
33 import jdk.internal.vm.annotation.ForceInline;
34 import jdk.internal.vm.annotation.IntrinsicCandidate;
35 import jdk.internal.vm.annotation.Stable;
36
37 import java.lang.annotation.Native;
38 import java.lang.constant.Constable;
39 import java.lang.constant.ConstantDesc;
40 import java.lang.invoke.MethodHandles;
41 import java.util.Objects;
42 import java.util.Optional;
43
44 import static java.lang.Character.digit;
45 import static java.lang.String.COMPACT_STRINGS;
46
47 /**
48 * The {@code Integer} class is the {@linkplain
49 * java.lang##wrapperClass wrapper class} for values of the primitive
50 * type {@code int}. An object of type {@code Integer} contains a
51 * single field whose type is {@code int}.
52 *
53 * <p>In addition, this class provides several methods for converting
54 * an {@code int} to a {@code String} and a {@code String} to an
55 * {@code int}, as well as other constants and methods useful when
56 * dealing with an {@code int}.
57 *
58 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
59 * class; programmers should treat instances that are
60 * {@linkplain #equals(Object) equal} as interchangeable and should not
61 * use instances for synchronization, or unpredictable behavior may
62 * occur. For example, in a future release, synchronization may fail.
63 *
64 * <p>Implementation note: The implementations of the "bit twiddling"
65 * methods (such as {@link #highestOneBit(int) highestOneBit} and
66 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
67 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
68 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
69 * Delight, Second Edition</cite>, (Pearson Education, 2013).
70 *
71 * @since 1.0
72 */
73 @jdk.internal.ValueBased
74 public final class Integer extends Number
75 implements Comparable<Integer>, Constable, ConstantDesc {
76 /**
77 * A constant holding the minimum value an {@code int} can
78 * have, -2<sup>31</sup>.
79 */
80 @Native public static final int MIN_VALUE = 0x80000000;
81
82 /**
83 * A constant holding the maximum value an {@code int} can
84 * have, 2<sup>31</sup>-1.
85 */
86 @Native public static final int MAX_VALUE = 0x7fffffff;
87
88 /**
89 * The {@code Class} instance representing the primitive type
90 * {@code int}.
91 *
92 * @since 1.1
885 * During VM initialization, java.lang.Integer.IntegerCache.high property
886 * may be set and saved in the private system properties in the
887 * jdk.internal.misc.VM class.
888 *
889 * WARNING: The cache is archived with CDS and reloaded from the shared
890 * archive at runtime. The archived cache (Integer[]) and Integer objects
891 * reside in the closed archive heap regions. Care should be taken when
892 * changing the implementation and the cache array should not be assigned
893 * with new Integer object(s) after initialization.
894 */
895
896 @AOTSafeClassInitializer
897 private static final class IntegerCache {
898 static final int low = -128;
899 @Stable static int high;
900
901 @Stable static Integer[] cache;
902 static Integer[] archivedCache;
903
904 static {
905 runtimeSetup();
906 }
907
908 @AOTRuntimeSetup
909 private static void runtimeSetup() {
910 // high value may be configured by property
911 int h = 127;
912 String integerCacheHighPropValue =
913 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
914 if (integerCacheHighPropValue != null) {
915 try {
916 h = Math.max(parseInt(integerCacheHighPropValue), 127);
917 // Maximum array size is Integer.MAX_VALUE
918 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
919 } catch( NumberFormatException nfe) {
920 // If the property cannot be parsed into an int, ignore it.
921 }
922 }
923 high = h;
924
925 Integer[] precomputed = null;
954 // Otherwise, the Integers from the AOT cache (or CDS archive) will not
955 // have the same object identity as items in IntegerCache.cache[].
956 int precomputedSize = (precomputed == null) ? 0 : precomputed.length;
957 for (int i = 0; i < precomputedSize; i++) {
958 c[i] = precomputed[i];
959 assert j == precomputed[i];
960 j++;
961 }
962 // Fill the rest of the cache.
963 for (int i = precomputedSize; i < size; i++) {
964 c[i] = new Integer(j++);
965 }
966 return c;
967 }
968
969 private IntegerCache() {}
970 }
971
972 /**
973 * Returns an {@code Integer} instance representing the specified
974 * {@code int} value. If a new {@code Integer} instance is not
975 * required, this method should generally be used in preference to
976 * the constructor {@link #Integer(int)}, as this method is likely
977 * to yield significantly better space and time performance by
978 * caching frequently requested values.
979 *
980 * This method will always cache values in the range -128 to 127,
981 * inclusive, and may cache other values outside of this range.
982 *
983 * @param i an {@code int} value.
984 * @return an {@code Integer} instance representing {@code i}.
985 * @since 1.5
986 */
987 @IntrinsicCandidate
988 public static Integer valueOf(int i) {
989 if (i >= IntegerCache.low && i <= IntegerCache.high)
990 return IntegerCache.cache[i + (-IntegerCache.low)];
991 return new Integer(i);
992 }
993
994 /**
995 * The value of the {@code Integer}.
996 *
997 * @serial
998 */
999 private final int value;
1000
1001 /**
1002 * Constructs a newly allocated {@code Integer} object that
1003 * represents the specified {@code int} value.
1004 *
1005 * @param value the value to be represented by the
1006 * {@code Integer} object.
1007 *
1008 * @deprecated
1009 * It is rarely appropriate to use this constructor. The static factory
1010 * {@link #valueOf(int)} is generally a better choice, as it is
|
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import jdk.internal.misc.CDS;
29 import jdk.internal.misc.PreviewFeatures;
30 import jdk.internal.misc.VM;
31 import jdk.internal.util.DecimalDigits;
32 import jdk.internal.value.DeserializeConstructor;
33 import jdk.internal.vm.annotation.AOTRuntimeSetup;
34 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
35 import jdk.internal.vm.annotation.ForceInline;
36 import jdk.internal.vm.annotation.IntrinsicCandidate;
37 import jdk.internal.vm.annotation.Stable;
38
39 import java.lang.annotation.Native;
40 import java.lang.constant.Constable;
41 import java.lang.constant.ConstantDesc;
42 import java.lang.invoke.MethodHandles;
43 import java.util.Objects;
44 import java.util.Optional;
45
46 import static java.lang.Character.digit;
47 import static java.lang.String.COMPACT_STRINGS;
48
49 /**
50 * The {@code Integer} class is the {@linkplain
51 * java.lang##wrapperClass wrapper class} for values of the primitive
52 * type {@code int}. An object of type {@code Integer} contains a
53 * single field whose type is {@code int}.
54 *
55 * <p>In addition, this class provides several methods for converting
56 * an {@code int} to a {@code String} and a {@code String} to an
57 * {@code int}, as well as other constants and methods useful when
58 * dealing with an {@code int}.
59 *
60 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
61 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
62 * as interchangeable and should not use instances for synchronization, mutexes, or
63 * with {@linkplain java.lang.ref.Reference object references}.
64 *
65 * <div class="preview-block">
66 * <div class="preview-comment">
67 * When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
68 * Use of value class instances for synchronization, mutexes, or with
69 * {@linkplain java.lang.ref.Reference object references} result in
70 * {@link IdentityException}.
71 * </div>
72 * </div>
73 *
74 * <p>Implementation note: The implementations of the "bit twiddling"
75 * methods (such as {@link #highestOneBit(int) highestOneBit} and
76 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
77 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
78 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
79 * Delight, Second Edition</cite>, (Pearson Education, 2013).
80 *
81 * @since 1.0
82 */
83 @jdk.internal.MigratedValueClass
84 @jdk.internal.ValueBased
85 public final class Integer extends Number
86 implements Comparable<Integer>, Constable, ConstantDesc {
87 /**
88 * A constant holding the minimum value an {@code int} can
89 * have, -2<sup>31</sup>.
90 */
91 @Native public static final int MIN_VALUE = 0x80000000;
92
93 /**
94 * A constant holding the maximum value an {@code int} can
95 * have, 2<sup>31</sup>-1.
96 */
97 @Native public static final int MAX_VALUE = 0x7fffffff;
98
99 /**
100 * The {@code Class} instance representing the primitive type
101 * {@code int}.
102 *
103 * @since 1.1
896 * During VM initialization, java.lang.Integer.IntegerCache.high property
897 * may be set and saved in the private system properties in the
898 * jdk.internal.misc.VM class.
899 *
900 * WARNING: The cache is archived with CDS and reloaded from the shared
901 * archive at runtime. The archived cache (Integer[]) and Integer objects
902 * reside in the closed archive heap regions. Care should be taken when
903 * changing the implementation and the cache array should not be assigned
904 * with new Integer object(s) after initialization.
905 */
906
907 @AOTSafeClassInitializer
908 private static final class IntegerCache {
909 static final int low = -128;
910 @Stable static int high;
911
912 @Stable static Integer[] cache;
913 static Integer[] archivedCache;
914
915 static {
916 if (!PreviewFeatures.isEnabled()) {
917 runtimeSetup();
918 } else {
919 cache = null;
920 assert archivedCache == null;
921 }
922 }
923
924 @AOTRuntimeSetup
925 private static void runtimeSetup() {
926 // high value may be configured by property
927 int h = 127;
928 String integerCacheHighPropValue =
929 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
930 if (integerCacheHighPropValue != null) {
931 try {
932 h = Math.max(parseInt(integerCacheHighPropValue), 127);
933 // Maximum array size is Integer.MAX_VALUE
934 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
935 } catch( NumberFormatException nfe) {
936 // If the property cannot be parsed into an int, ignore it.
937 }
938 }
939 high = h;
940
941 Integer[] precomputed = null;
970 // Otherwise, the Integers from the AOT cache (or CDS archive) will not
971 // have the same object identity as items in IntegerCache.cache[].
972 int precomputedSize = (precomputed == null) ? 0 : precomputed.length;
973 for (int i = 0; i < precomputedSize; i++) {
974 c[i] = precomputed[i];
975 assert j == precomputed[i];
976 j++;
977 }
978 // Fill the rest of the cache.
979 for (int i = precomputedSize; i < size; i++) {
980 c[i] = new Integer(j++);
981 }
982 return c;
983 }
984
985 private IntegerCache() {}
986 }
987
988 /**
989 * Returns an {@code Integer} instance representing the specified
990 * {@code int} value.
991 * <div class="preview-block">
992 * <div class="preview-comment">
993 * <p>
994 * - When preview features are NOT enabled, {@code Integer} is an identity class.
995 * If a new {@code Integer} instance is not
996 * required, this method should generally be used in preference to
997 * the constructor {@link #Integer(int)}, as this method is likely
998 * to yield significantly better space and time performance by
999 * caching frequently requested values.
1000 * This method will always cache values in the range -128 to 127,
1001 * inclusive, and may cache other values outside of this range.
1002 * </p>
1003 * <p>
1004 * - When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
1005 * The {@code valueOf} behavior is the same as invoking the constructor,
1006 * whether cached or not.
1007 * </p>
1008 * </div>
1009 * </div>
1010 *
1011 * @param i an {@code int} value.
1012 * @return an {@code Integer} instance representing {@code i}.
1013 * @since 1.5
1014 */
1015 @IntrinsicCandidate
1016 @DeserializeConstructor
1017 public static Integer valueOf(int i) {
1018 if (!PreviewFeatures.isEnabled()) {
1019 if (i >= IntegerCache.low && i <= IntegerCache.high)
1020 return IntegerCache.cache[i + (-IntegerCache.low)];
1021 }
1022 return new Integer(i);
1023 }
1024
1025 /**
1026 * The value of the {@code Integer}.
1027 *
1028 * @serial
1029 */
1030 private final int value;
1031
1032 /**
1033 * Constructs a newly allocated {@code Integer} object that
1034 * represents the specified {@code int} value.
1035 *
1036 * @param value the value to be represented by the
1037 * {@code Integer} object.
1038 *
1039 * @deprecated
1040 * It is rarely appropriate to use this constructor. The static factory
1041 * {@link #valueOf(int)} is generally a better choice, as it is
|