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
93 */
94 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
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;
926 if (cache != null) {
927 // IntegerCache has been AOT-initialized.
928 precomputed = cache;
929 } else {
930 // Legacy CDS archive support (to be deprecated):
931 // Load IntegerCache.archivedCache from archive, if possible
932 CDS.initializeFromArchive(IntegerCache.class);
933 precomputed = archivedCache;
934 }
935
936 cache = loadOrInitializeCache(precomputed);
937 archivedCache = cache; // Legacy CDS archive support (to be deprecated)
938 // range [-128, 127] must be interned (JLS7 5.1.7)
939 assert IntegerCache.high >= 127;
940 }
941
942 private static Integer[] loadOrInitializeCache(Integer[] precomputed) {
943 int size = (high - low) + 1;
944
945 // Use the precomputed cache if it exists and is large enough
946 if (precomputed != null && size <= precomputed.length) {
947 return precomputed;
948 }
949
950 Integer[] c = new Integer[size];
951 int j = low;
952 // If we loading a precomputed cache (from AOT cache or CDS archive),
953 // we must use all instances from it.
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
1011 * likely to yield significantly better space and time performance.
1012 */
1013 @Deprecated(since="9")
1014 public Integer(int value) {
1015 this.value = value;
1016 }
1017
1018 /**
1019 * Constructs a newly allocated {@code Integer} object that
1020 * represents the {@code int} value indicated by the
1021 * {@code String} parameter. The string is converted to an
1022 * {@code int} value in exactly the manner used by the
1023 * {@code parseInt} method for radix 10.
1024 *
1025 * @param s the {@code String} to be converted to an {@code Integer}.
1026 * @throws NumberFormatException if the {@code String} does not
1027 * contain a parsable integer.
1028 *
1029 * @deprecated
1030 * It is rarely appropriate to use this constructor.
1031 * Use {@link #parseInt(String)} to convert a string to a
1032 * {@code int} primitive, or use {@link #valueOf(String)}
1033 * to convert a string to an {@code Integer} object.
|
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.Deserializer;
33 import jdk.internal.value.ValueClass;
34 import jdk.internal.vm.annotation.AOTRuntimeSetup;
35 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
36 import jdk.internal.vm.annotation.ForceInline;
37 import jdk.internal.vm.annotation.IntrinsicCandidate;
38 import jdk.internal.vm.annotation.Stable;
39
40 import java.lang.annotation.Native;
41 import java.lang.constant.Constable;
42 import java.lang.constant.ConstantDesc;
43 import java.lang.invoke.MethodHandles;
44 import java.util.Objects;
45 import java.util.Optional;
46
47 import static java.lang.Character.digit;
48 import static java.lang.String.COMPACT_STRINGS;
49
50 /**
51 * The {@code Integer} class is the {@linkplain
52 * java.lang##wrapperClass wrapper class} for values of the primitive
53 * type {@code int}. An object of type {@code Integer} contains a
54 * single field whose type is {@code int}.
55 *
56 * <p>In addition, this class provides several methods for converting
57 * an {@code int} to a {@code String} and a {@code String} to an
58 * {@code int}, as well as other constants and methods useful when
59 * dealing with an {@code int}.
60 *
61 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
62 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
63 * as interchangeable and should not use instances for synchronization or
64 * with {@linkplain java.lang.ref.Reference object references}.
65 *
66 * <div class="preview-block">
67 * <div class="preview-comment">
68 * When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
69 * Use of value class instances for synchronization or with
70 * {@linkplain java.lang.ref.Reference object references} result in
71 * {@link IdentityException}.
72 * </div>
73 * </div>
74 *
75 * <p>Implementation note: The implementations of the "bit twiddling"
76 * methods (such as {@link #highestOneBit(int) highestOneBit} and
77 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
78 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
79 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
80 * Delight, Second Edition</cite>, (Pearson Education, 2013).
81 *
82 * @since 1.0
83 */
84 @jdk.internal.ValueBased
85 public final /*value*/ 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
104 */
105 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
916 runtimeSetup();
917 }
918
919 @AOTRuntimeSetup
920 private static void runtimeSetup() {
921 // high value may be configured by property
922 int h = 127;
923 String integerCacheHighPropValue =
924 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
925 if (integerCacheHighPropValue != null) {
926 try {
927 h = Math.max(parseInt(integerCacheHighPropValue), 127);
928 // Maximum array size is Integer.MAX_VALUE
929 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
930 } catch( NumberFormatException nfe) {
931 // If the property cannot be parsed into an int, ignore it.
932 }
933 }
934 high = h;
935
936 Integer[] precomputed;
937 if (cache != null) {
938 // IntegerCache has been AOT-initialized.
939 precomputed = cache;
940 } else {
941 // Legacy CDS archive support (to be deprecated):
942 // Load IntegerCache.archivedCache from archive, if possible
943 CDS.initializeFromArchive(IntegerCache.class);
944 precomputed = archivedCache;
945 }
946
947 cache = loadOrInitializeCache(precomputed);
948 archivedCache = cache; // Legacy CDS archive support (to be deprecated)
949 // range [-128, 127] must be interned (JLS7 5.1.7)
950 assert IntegerCache.high >= 127;
951 }
952
953 private static Integer[] loadOrInitializeCache(Integer[] precomputed) {
954 int size = (high - low) + 1;
955
956 // Use the precomputed cache if it exists and is large enough
957 if (precomputed != null && size <= precomputed.length) {
958 return precomputed;
959 }
960
961 Integer[] c = newCacheArray(size);
962 int j = low;
963 // If we loading a precomputed cache (from AOT cache or CDS archive),
964 // we must use all instances from it.
965 // Otherwise, the Integers from the AOT cache (or CDS archive) will not
966 // have the same object identity as items in IntegerCache.cache[].
967 int precomputedSize = (precomputed == null) ? 0 : precomputed.length;
968 for (int i = 0; i < precomputedSize; i++) {
969 c[i] = precomputed[i];
970 assert j == precomputed[i];
971 j++;
972 }
973 // Fill the rest of the cache.
974 for (int i = precomputedSize; i < size; i++) {
975 c[i] = new Integer(j++);
976 }
977 return c;
978 }
979
980 private static Integer[] newCacheArray(int size) {
981 // ValueClass.newReferenceArray requires a value class component.
982 if (PreviewFeatures.isEnabled()) {
983 return (Integer[]) ValueClass.newReferenceArray(Integer.class, size);
984 }
985 return new Integer[size];
986 }
987
988 private IntegerCache() {}
989 }
990
991 /**
992 * Returns an {@code Integer} instance representing the specified
993 * {@code int} value.
994 * <div class="preview-block">
995 * <div class="preview-comment">
996 * <p>
997 * - When preview features are NOT enabled, {@code Integer} is an identity class.
998 * If a new {@code Integer} instance is not
999 * required, this method should generally be used in preference to
1000 * the constructor {@link #Integer(int)}, as this method is likely
1001 * to yield significantly better space and time performance by
1002 * caching frequently requested values.
1003 * This method will always cache values in the range -128 to 127,
1004 * inclusive, and may cache other values outside of this range.
1005 * </p>
1006 * <p>
1007 * - When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
1008 * The {@code valueOf} behavior is the same as invoking the constructor,
1009 * whether cached or not.
1010 * </p>
1011 * </div>
1012 * </div>
1013 *
1014 * @param i an {@code int} value.
1015 * @return an {@code Integer} instance representing {@code i}.
1016 * @since 1.5
1017 */
1018 @IntrinsicCandidate
1019 public static Integer valueOf(int i) {
1020 if (i >= IntegerCache.low && i <= IntegerCache.high)
1021 return IntegerCache.cache[i + (-IntegerCache.low)];
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
1042 * likely to yield significantly better space and time performance.
1043 */
1044 @Deprecated(since="9")
1045 @Deserializer("value")
1046 public Integer(int value) {
1047 this.value = value;
1048 }
1049
1050 /**
1051 * Constructs a newly allocated {@code Integer} object that
1052 * represents the {@code int} value indicated by the
1053 * {@code String} parameter. The string is converted to an
1054 * {@code int} value in exactly the manner used by the
1055 * {@code parseInt} method for radix 10.
1056 *
1057 * @param s the {@code String} to be converted to an {@code Integer}.
1058 * @throws NumberFormatException if the {@code String} does not
1059 * contain a parsable integer.
1060 *
1061 * @deprecated
1062 * It is rarely appropriate to use this constructor.
1063 * Use {@link #parseInt(String)} to convert a string to a
1064 * {@code int} primitive, or use {@link #valueOf(String)}
1065 * to convert a string to an {@code Integer} object.
|