New APIs in Java 21

Comparing Java 21 (21.0.2+13-LTS-tem) with Java 18 (18.0.2.1+1-tem).

Element	Modification
java.base
java.io
BufferedInputStream
transferTo(OutputStream)	added
Console	- final + sealed
InvalidClassException
InvalidClassException(String, String, Throwable)	added
InvalidClassException(String, Throwable)	added
InvalidObjectException
InvalidObjectException(String, Throwable)	added
ObjectStreamClass	+ final
ObjectStreamException
ObjectStreamException(String, Throwable)	added
ObjectStreamException(Throwable)	added
PushbackInputStream
transferTo(OutputStream)	added
SequenceInputStream
transferTo(OutputStream)	added
java.lang.constant
ConstantDescs
BSM_CLASS_DATA	added
BSM_CLASS_DATA_AT	added
CLASS_INIT_NAME	added
INIT_NAME	added
MTD_void	added
ClassDesc
ofInternalName(String)	added
resolveConstantDesc(MethodHandles.Lookup)	added
MethodHandleDesc
resolveConstantDesc(MethodHandles.Lookup)	added
MethodTypeDesc
descriptorString()	+ abstract
of(ClassDesc)	added
of(ClassDesc, List)	added
resolveConstantDesc(MethodHandles.Lookup)	added
ModuleDesc	added
PackageDesc	added
java.lang.foreign	added
java.lang.invoke
CallSite	+ sealed
ClassSpecializer.Factory	removed
ClassSpecializer.SpeciesData	removed
MethodHandle	+ sealed
MethodHandles
collectCoordinates(VarHandle, int, MethodHandle)	added preview
dropCoordinates(VarHandle, int, Class...)	added preview
filterCoordinates(VarHandle, int, MethodHandle...)	added preview
filterValue(VarHandle, MethodHandle, MethodHandle)	added preview
insertCoordinates(VarHandle, int, Object...)	added preview
memorySegmentViewVarHandle(ValueLayout)	added preview
permuteCoordinates(VarHandle, List, int...)	added preview
StringConcatFactory
MAX_INDY_CONCAT_ARG_SLOTS	added preview
makeConcatWithTemplate(List, List)	added preview
makeConcatWithTemplateCluster(List, List, int)	added preview
makeConcatWithTemplateGetters(List, List, int)	added preview
VarHandle	+ sealed
isAccessModeSupported(VarHandle.AccessMode)	- final
java.lang.module
ModuleDescriptor.Exports
accessFlags()	added
ModuleDescriptor.Opens
accessFlags()	added
ModuleDescriptor.Requires
accessFlags()	added
ModuleDescriptor
accessFlags()	added
java.lang.ref
ReferenceQueue
remove(long)	- throws IllegalArgumentException
Reference	+ sealed
java.lang.reflect
Executable
accessFlags()	added
getParameterCount()	+ abstract
Field
accessFlags()	added
Parameter
accessFlags()	added
AccessFlag.Location	added
AccessFlag	added
ClassFileFormatVersion	added
Member
accessFlags()	added
java.lang.runtime
SwitchBootstraps	- preview
TemplateRuntime	added preview
java.lang
Character.UnicodeBlock
ARABIC_EXTENDED_B	added
ARABIC_EXTENDED_C	added
CJK_UNIFIED_IDEOGRAPHS_EXTENSION_H	added
CYPRO_MINOAN	added
CYRILLIC_EXTENDED_D	added
DEVANAGARI_EXTENDED_A	added
ETHIOPIC_EXTENDED_B	added
KAKTOVIK_NUMERALS	added
KANA_EXTENDED_B	added
KAWI	added
LATIN_EXTENDED_F	added
LATIN_EXTENDED_G	added
NAG_MUNDARI	added
OLD_UYGHUR	added
TANGSA	added
TOTO	added
UNIFIED_CANADIAN_ABORIGINAL_SYLLABICS_EXTENDED_A	added
VITHKUQI	added
ZNAMENNY_MUSICAL_NOTATION	added
Character
isEmoji(int)	added
isEmojiComponent(int)	added
isEmojiModifier(int)	added
isEmojiModifierBase(int)	added
isEmojiPresentation(int)	added
isExtendedPictographic(int)	added
Class
accessFlags()	added
isUnnamedClass()	added preview
Compiler	removed
Double
PRECISION	added
FdLibm.Cbrt	removed
FdLibm.Hypot	removed
FdLibm.Pow	removed
Float
PRECISION	added
float16ToFloat(short)	added
floatToFloat16(float)	added
Integer
compress(int, int)	added
expand(int, int)	added
Long
compress(long, long)	added
expand(long, long)	added
MatchException	added
Math
TAU	added
clamp(double, double, double)	added
clamp(float, float, float)	added
clamp(long, int, int)	added
clamp(long, long, long)	added
ModuleLayer.Controller
enableNativeAccess(Module)	added preview
Module
isNativeAccessEnabled()	added preview
ScopedValue.Carrier	added preview
ScopedValue	added preview
StrictMath
TAU	added
clamp(double, double, double)	added
clamp(float, float, float)	added
clamp(long, int, int)	added
clamp(long, long, long)	added
StringBuffer	+ implements Appendable
repeat(CharSequence, int)	added
repeat(int, int)	added
StringBuilder	+ implements Appendable
repeat(CharSequence, int)	added
repeat(int, int)	added
String
indexOf(String, int, int)	added
indexOf(int, int, int)	added
splitWithDelimiters(String, int)	added
ThreadDeath	+ deprecated + forRemoval
ThreadGroup
allowThreadSuspension(boolean)	removed
Thread
getId()	+ deprecated
isVirtual()	added
join(Duration)	added
ofPlatform()	added
ofVirtual()	added
sleep(Duration)	added
startVirtualThread(Runnable)	added
threadId()	added
WrongThreadException	added
Character.UnicodeScript
CYPRO_MINOAN	added
KAWI	added
NAG_MUNDARI	added
OLD_UYGHUR	added
TANGSA	added
TOTO	added
VITHKUQI	added
StringTemplate.Processor.Linkage	added preview
StringTemplate.Processor	added preview
StringTemplate	added preview
Thread.Builder.OfPlatform	added
Thread.Builder.OfVirtual	added
Thread.Builder	added
java.math
BigDecimal
TWO	added
BigInteger
parallelMultiply(BigInteger)	added
java.net
InetAddress	+ sealed
SocketException
SocketException(String, Throwable)	added
SocketException(Throwable)	added
URL
URL(String)	+ deprecated
URL(String, String, String)	+ deprecated
URL(String, String, int, String)	+ deprecated
URL(String, String, int, String, URLStreamHandler)	+ deprecated
URL(URL, String)	+ deprecated
URL(URL, String, URLStreamHandler)	+ deprecated
of(URI, URLStreamHandler)	added
java.nio.channels
FileChannel
map(FileChannel.MapMode, long, long, Arena)	added preview
java.nio.file.spi
FileSystemProvider
exists(Path, LinkOption...)	added
readAttributesIfExists(Path, Class, LinkOption...)	added
java.nio
Buffer	+ sealed
ByteBuffer	+ sealed
CharBuffer	+ sealed
DoubleBuffer	+ sealed
FloatBuffer	+ sealed
IntBuffer	+ sealed
LongBuffer	+ sealed
MappedByteBuffer	+ sealed
ShortBuffer	+ sealed
java.security.interfaces
DSAKeyPairGenerator
initialize(DSAParams, SecureRandom)	- throws InvalidParameterException
initialize(int, boolean, SecureRandom)	- throws InvalidParameterException
java.security.spec
PSSParameterSpec
DEFAULT	+ deprecated
PSSParameterSpec(int)	+ deprecated
java.security
InvalidParameterException
InvalidParameterException(String, Throwable)	added
InvalidParameterException(Throwable)	added
java.text
DecimalFormatSymbols
getLocale()	added
java.time.chrono
IsoChronology
isIsoBased()	added
JapaneseChronology
isIsoBased()	added
MinguoChronology
isIsoBased()	added
ThaiBuddhistChronology
isIsoBased()	added
Chronology
isIsoBased()	added
java.time.format
DateTimeFormatterBuilder
appendLocalized(String)	added
getLocalizedDateTimePattern(String, Chronology,...	added
DateTimeFormatter
ofLocalizedPattern(String)	added
java.time
ZoneId	+ sealed
ZoneOffset
normalized()	added
java.util.concurrent
CompletableFuture
exceptionNow()	added
resultNow()	added
state()	added
ConcurrentHashMap.KeySetView	+ final
ConcurrentSkipListMap
putFirst(Object, Object)	added
putLast(Object, Object)	added
ConcurrentSkipListSet
addFirst(Object)	added
addLast(Object)	added
CopyOnWriteArrayList
addFirst(Object)	added
addLast(Object)	added
getFirst()	added
getLast()	added
removeFirst()	added
removeLast()	added
reversed()	added
DelayQueue
remove()	added
Executors
newThreadPerTaskExecutor(ThreadFactory)	added
newVirtualThreadPerTaskExecutor()	added
ForkJoinPool
close()	added
externalSubmit(ForkJoinTask)	added
lazySubmit(ForkJoinTask)	added
setParallelism(int)	added
ForkJoinTask
adaptInterruptible(Callable)	added
exceptionNow()	added
quietlyJoin(long, TimeUnit)	added
quietlyJoinUninterruptibly(long, TimeUnit)	added
resultNow()	added
state()	added
ForkJoinWorkerThread
ForkJoinWorkerThread(ThreadGroup, ForkJoinPool,...	added
getQueuedTaskCount()	added
FutureTask
exceptionNow()	added
resultNow()	added
state()	added
StructureViolationException	added preview
StructuredTaskScope.ShutdownOnFailure	added preview
StructuredTaskScope.ShutdownOnSuccess	added preview
StructuredTaskScope	added preview
ThreadLocalRandom	+ final
Future.State	added
StructuredTaskScope.Subtask.State	added preview
ExecutorService	+ implements AutoCloseable
close()	added
Future
exceptionNow()	added
resultNow()	added
state()	added
StructuredTaskScope.Subtask	added preview
java.util.regex
Matcher
hasMatch()	added
namedGroups()	added
Pattern
namedGroups()	added
splitWithDelimiters(CharSequence, int)	added
MatchResult
end(String)	added
group(String)	added
hasMatch()	added
namedGroups()	added
start(String)	added
java.util.spi
ToolProvider
description()	added
java.util.zip
ZipInputStream
read()	added
readAllBytes()	added
readNBytes(byte[], int, int)	added
readNBytes(int)	added
skipNBytes(long)	added
transferTo(OutputStream)	added
java.util
ArrayList
addFirst(Object)	added
addLast(Object)	added
getFirst()	added
getLast()	added
removeFirst()	added
removeLast()	added
Arrays	+ final
Collections
newSequencedSetFromMap(SequencedMap)	added
shuffle(List, RandomGenerator)	added
unmodifiableSequencedCollection(SequencedCollectio...	added
unmodifiableSequencedMap(SequencedMap)	added
unmodifiableSequencedSet(SequencedSet)	added
EnumSet	+ sealed
FormatProcessor	added preview
HashMap
newHashMap(int)	added
HashSet
newHashSet(int)	added
IdentityHashMap
remove(Object, Object)	added
replace(Object, Object, Object)	added
IllegalFormatException	+ sealed
LinkedHashMap	- implements Map + implements SequencedMap
newLinkedHashMap(int)	added
putFirst(Object, Object)	added
putLast(Object, Object)	added
reversed()	added
sequencedEntrySet()	added
sequencedKeySet()	added
sequencedValues()	added
LinkedHashSet	- implements Set + implements SequencedSet
addFirst(Object)	added
addLast(Object)	added
getFirst()	added
getLast()	added
newLinkedHashSet(int)	added
removeFirst()	added
removeLast()	added
reversed()	added
LinkedList
reversed()	added
Locale
Locale(String)	+ deprecated
Locale(String, String)	+ deprecated
Locale(String, String, String)	+ deprecated
availableLocales()	added
caseFoldLanguageTag(String)	added
of(String)	added
of(String, String)	added
of(String, String, String)	added
Objects
toIdentityString(Object)	added
Random
from(RandomGenerator)	added
TreeMap
putFirst(Object, Object)	added
putLast(Object, Object)	added
TreeSet
addFirst(Object)	added
addLast(Object)	added
WeakHashMap
newWeakHashMap(int)	added
Deque	+ implements SequencedCollection
reversed()	added
List	- implements Collection + implements SequencedCollection
addFirst(Object)	added
addLast(Object)	added
getFirst()	added
getLast()	added
removeFirst()	added
removeLast()	added
reversed()	added
NavigableMap
reversed()	added
NavigableSet
removeFirst()	added
removeLast()	added
reversed()	added
SequencedCollection	added
SequencedMap	added
SequencedSet	added
SortedMap	- implements Map + implements SequencedMap
putFirst(Object, Object)	added
putLast(Object, Object)	added
reversed()	added
SortedSet	+ implements SequencedSet
addFirst(Object)	added
addLast(Object)	added
getFirst()	added
getLast()	added
removeFirst()	added
removeLast()	added
reversed()	added
javax.crypto.spec
OAEPParameterSpec
DEFAULT	+ deprecated
javax.crypto
DecapsulateException	added
KEM.Decapsulator	added
KEM.Encapsulated	added
KEM.Encapsulator	added
KEM	added
KEMSpi.DecapsulatorSpi	added
KEMSpi.EncapsulatorSpi	added
KEMSpi	added
javax.net.ssl
SSLHandshakeException
SSLHandshakeException(String, Throwable)	added
SSLKeyException
SSLKeyException(String, Throwable)	added
SSLParameters
getNamedGroups()	added
getSignatureSchemes()	added
setNamedGroups(String[])	added
setSignatureSchemes(String[])	added
SSLPeerUnverifiedException
SSLPeerUnverifiedException(String, Throwable)	added
SSLProtocolException
SSLProtocolException(String, Throwable)	added
SSLSessionContext
setSessionCacheSize(int)	- throws IllegalArgumentException
setSessionTimeout(int)	- throws IllegalArgumentException
java.compiler
javax.lang.model.element
ElementKind
isDeclaredType()	added
isExecutable()	added
isInitializer()	added
isVariable()	added
TypeElement
isUnnamed()	added preview
VariableElement
isUnnamed()	added preview
javax.lang.model.util
Elements
isCanonicalConstructor(ExecutableElement)	added
isCompactConstructor(ExecutableElement)	added
javax.lang.model
SourceVersion
RELEASE_19	added
RELEASE_20	added
RELEASE_21	added
java.desktop
java.awt.color
ICC_ProfileGray	+ final
ICC_ProfileRGB	+ final
ICC_Profile	+ sealed
java.awt.desktop
AppEvent	+ sealed
FilesEvent	+ sealed
java.awt.dnd
DropTargetContext	+ final
java.awt.event
InputEvent	+ sealed
java.awt.geom
CubicCurve2D.Double
getBounds2D()	removed
CubicCurve2D.Float
getBounds2D()	removed
CubicCurve2D
getBounds2D()	added
Path2D	+ sealed
QuadCurve2D.Double
getBounds2D()	removed
QuadCurve2D.Float
getBounds2D()	removed
QuadCurve2D
getBounds2D()	added
java.awt
GridBagLayoutInfo	+ final
MultipleGradientPaint	+ sealed
PointerInfo	+ final
ScrollPaneAdjustable	+ final
TextComponent	+ sealed
javax.sound.midi
Track	+ final
javax.swing.plaf.basic
BasicDirectoryModel
intervalAdded(ListDataEvent)	+ forRemoval
intervalRemoved(ListDataEvent)	+ forRemoval
lt(File, File)	+ forRemoval
BasicMenuItemUI.MouseInputHandler	+ forRemoval
BasicScrollPaneUI.HSBChangeListener	+ forRemoval
BasicScrollPaneUI.PropertyChangeHandler	+ forRemoval
BasicScrollPaneUI.VSBChangeListener	+ forRemoval
BasicScrollPaneUI.ViewportChangeHandler	+ forRemoval
BasicSplitPaneUI.BasicHorizontalLayoutManager	+ sealed
BasicToolBarUI
createFloatingFrame(JToolBar)	+ forRemoval
javax.swing.plaf.synth
SynthComboBoxUI
getMinimumSize(JComponent)	added
SynthLookAndFeel
load(URL)	+ deprecated + forRemoval
SynthPasswordFieldUI
installDefaults()	added
javax.swing.text.html
AccessibleHTML.HTMLAccessibleContext
setElementInfo(AccessibleHTML.ElementInfo)	added
FormSubmitEvent	+ final
StyleSheet.BoxPainter	+ final
StyleSheet.ListPainter	+ final
javax.swing.text
DefaultEditorKit
beginLineUpAction	added
endLineDownAction	added
StyleConstants.CharacterConstants	+ final
StyleConstants.ColorConstants	+ final
StyleConstants.FontConstants	+ final
StyleConstants.ParagraphConstants	+ final
StyleConstants	+ sealed
javax.swing
GroupLayout.Group	+ sealed
GroupLayout.ParallelGroup	+ sealed
GroupLayout.SequentialGroup	+ final
ToolTipManager	+ final
java.management.rmi
javax.management.remote.rmi
RMIIIOPServerImpl	removed
java.management
javax.management.loading
MLetContent	+ deprecated + forRemoval
MLet	+ deprecated + forRemoval
PrivateMLet	+ deprecated + forRemoval
MLetMBean	+ deprecated + forRemoval
javax.management.remote
JMXConnector
getMBeanServerConnection(Subject)	+ deprecated + forRemoval
java.net.http
java.net.http
HttpClient	+ implements AutoCloseable
awaitTermination(Duration)	added
close()	added
isTerminated()	added
shutdown()	added
shutdownNow()	added
HttpClient.Builder
localAddress(InetAddress)	added
java.xml.crypto
javax.xml.crypto.dsig
SignatureMethod
ED25519	added
ED448	added

Data Source

This report is based on simple comparison of all public and protected APIs of the java.* and javax.* packages of JDK builds 21.0.2+13-LTS-tem and 18.0.2.1+1-tem. It does not make statements about compatibility.

For the latest Java versions the corresponding CSRs (Compatibility & Specification Review) are linked for a quick reference to find out about the reasoning of the change.

More detailed API comparisons based on the japicmp tool can be found here.