New APIs in Java 21

Comparing Java 21 (21.0.1+12-LTS-tem) with Java 19 (19.0.2+7-tem).

Element	Modification
java.base
java.io
BufferedInputStream
transferTo(OutputStream)	added
Console	- final + sealed
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
ValueLayout.OfAddress	removed
AddressLayout	added preview
Addressable	removed
Arena	added preview
FunctionDescriptor	+ abstract
appendArgumentLayouts(MemoryLayout...)	+ abstract
argumentLayouts()	+ abstract
asVariadic(MemoryLayout...)	removed
changeReturnLayout(MemoryLayout)	+ abstract
dropReturnLayout()	+ abstract
equals(Object)	removed
firstVariadicArgumentIndex()	removed
hashCode()	removed
insertArgumentLayouts(int, MemoryLayout...)	+ abstract
returnLayout()	+ abstract
toMethodType()	added
toString()	removed
GroupLayout	- extends AbstractLayout - final + abstract + extends Object + sealed
equals(Object)	removed
hashCode()	removed
isStruct()	removed
isUnion()	removed
memberLayouts()	+ abstract
toString()	removed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withoutName()	added
Linker.Option	added preview
Linker
downcallHandle(Addressable, FunctionDescriptor)	removed
downcallHandle(FunctionDescriptor)	removed
downcallHandle(FunctionDescriptor,...	added
downcallHandle(MemorySegment, FunctionDescriptor,...	added
downcallType(FunctionDescriptor)	removed
upcallStub(MethodHandle, FunctionDescriptor,...	added
upcallStub(MethodHandle, FunctionDescriptor,...	removed
upcallType(FunctionDescriptor)	removed
MemoryAddress	removed
MemoryLayout.PathElement
dereferenceElement()	added
groupElement(long)	added
MemoryLayout
bitAlignment()	removed
bitOffset(MemoryLayout.PathElement...)	removed
bitOffsetHandle(MemoryLayout.PathElement...)	removed
bitSize()	removed
byteAlignment()	+ abstract
isPadding()	removed
paddingLayout(long)	added
paddingLayout(long)	removed
sequenceLayout(MemoryLayout)	added
structLayout(MemoryLayout...)	added
structLayout(MemoryLayout...)	removed
unionLayout(MemoryLayout...)	added
unionLayout(MemoryLayout...)	removed
valueLayout(Class, ByteOrder)	removed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withoutName()	added
MemorySegment.Scope	added preview
MemorySegment	- implements Addressable
NULL	added
address()	added
address()	removed
allocateNative(MemoryLayout, MemorySession)	removed
allocateNative(long, MemorySession)	removed
allocateNative(long, long, MemorySession)	removed
asSlice(long)	+ abstract
asSlice(long, MemoryLayout)	added
asSlice(long, long, long)	added
get(AddressLayout, long)	added
get(ValueLayout.OfAddress, long)	removed
getAtIndex(AddressLayout, long)	added
getAtIndex(ValueLayout.OfAddress, long)	removed
getAtIndex(ValueLayout.OfBoolean, long)	added
getAtIndex(ValueLayout.OfByte, long)	added
heapBase()	added
isAccessibleBy(Thread)	added
mismatch(MemorySegment)	- abstract
mismatch(MemorySegment, long, long, MemorySegment,...	added
ofAddress(MemoryAddress, long, MemorySession)	removed
ofAddress(long)	added
reinterpret(Arena, Consumer)	added
reinterpret(long)	added
reinterpret(long, Arena, Consumer)	added
scope()	added
session()	removed
set(AddressLayout, long, MemorySegment)	added
set(ValueLayout.OfAddress, long, Addressable)	removed
setAtIndex(AddressLayout, long, MemorySegment)	added
setAtIndex(ValueLayout.OfAddress, long,...	removed
setAtIndex(ValueLayout.OfBoolean, long, boolean)	added
setAtIndex(ValueLayout.OfByte, long, byte)	added
MemorySession	removed
PaddingLayout	added preview
SegmentAllocator
allocate(AddressLayout, MemorySegment)	added
allocate(ValueLayout.OfAddress, Addressable)	removed
implicitAllocator()	removed
newNativeArena(MemorySession)	removed
newNativeArena(long, MemorySession)	removed
newNativeArena(long, long, MemorySession)	removed
slicingAllocator(MemorySegment)	added
SequenceLayout	- extends AbstractLayout - final + abstract + extends Object + sealed
elementCount()	+ abstract
elementLayout()	+ abstract
equals(Object)	removed
flatten()	+ abstract
hashCode()	removed
reshape(long...)	+ abstract
toString()	removed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withElementCount(long)	+ abstract
withName(String)	+ abstract
withoutName()	added
StructLayout	added preview
SymbolLookup
find(String)	added
libraryLookup(Path, Arena)	added
libraryLookup(Path, MemorySession)	removed
libraryLookup(String, Arena)	added
libraryLookup(String, MemorySession)	removed
lookup(String)	removed
or(SymbolLookup)	added
UnionLayout	added preview
VaList.Builder	removed
VaList	removed
ValueLayout.OfBoolean	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfByte	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfChar	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfDouble	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfFloat	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfInt	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfLong	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout.OfShort	- extends ValueLayout - final + abstract + extends Object + implements ValueLayout + sealed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
ValueLayout	- extends AbstractLayout + abstract + extends Object
ADDRESS_UNALIGNED	added
JAVA_CHAR_UNALIGNED	added
JAVA_DOUBLE_UNALIGNED	added
JAVA_FLOAT_UNALIGNED	added
JAVA_INT_UNALIGNED	added
JAVA_LONG_UNALIGNED	added
JAVA_SHORT_UNALIGNED	added
arrayElementVarHandle(int...)	+ abstract
carrier()	+ abstract
equals(Object)	removed
hashCode()	removed
order()	+ abstract
toString()	removed
withBitAlignment(long)	removed
withByteAlignment(long)	added
withName(String)	+ abstract
withOrder(ByteOrder)	+ abstract
withoutName()	added
java.lang.invoke
ClassSpecializer.Factory	removed
ClassSpecializer.SpeciesData	removed
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
isAccessModeSupported(VarHandle.AccessMode)	- final
java.lang.module
ModuleDescriptor.Exports
accessFlags()	added
ModuleDescriptor.Opens
accessFlags()	added
ModuleDescriptor.Requires
accessFlags()	added
ModuleDescriptor
accessFlags()	added
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_C	added
CJK_UNIFIED_IDEOGRAPHS_EXTENSION_H	added
CYRILLIC_EXTENDED_D	added
DEVANAGARI_EXTENDED_A	added
KAKTOVIK_NUMERALS	added
KAWI	added
NAG_MUNDARI	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
FdLibm.Cbrt	removed
FdLibm.Hypot	removed
FdLibm.Pow	removed
Float
float16ToFloat(short)	added
floatToFloat16(float)	added
MatchException	- preview
Math
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
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
isVirtual()	- preview
ofPlatform()	- preview
ofVirtual()	- preview
startVirtualThread(Runnable)	- preview
Character.UnicodeScript
KAWI	added
NAG_MUNDARI	added
StringTemplate.Processor.Linkage	added preview
StringTemplate.Processor	added preview
StringTemplate	added preview
Thread.Builder.OfPlatform	- preview
allowSetThreadLocals(boolean)	removed
Thread.Builder.OfVirtual	- preview
allowSetThreadLocals(boolean)	removed
Thread.Builder	- preview
allowSetThreadLocals(boolean)	removed
java.net
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
map(FileChannel.MapMode, long, long,...	removed
java.nio.file.spi
FileSystemProvider
exists(Path, LinkOption...)	added
readAttributesIfExists(Path, Class, LinkOption...)	added
java.security.interfaces
DSAKeyPairGenerator
initialize(DSAParams, SecureRandom)	- throws InvalidParameterException
initialize(int, boolean, SecureRandom)	- throws InvalidParameterException
java.security
InvalidParameterException
InvalidParameterException(String, Throwable)	added
InvalidParameterException(Throwable)	added
java.util.concurrent
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)	- preview
newVirtualThreadPerTaskExecutor()	- preview
ForkJoinPool
externalSubmit(ForkJoinTask)	added
ForkJoinWorkerThread
getQueuedTaskCount()	added
StructureViolationException	added preview
StructuredTaskScope.ShutdownOnFailure	added preview
StructuredTaskScope.ShutdownOnSuccess	added preview
StructuredTaskScope	added preview
StructuredTaskScope.Subtask.State	added preview
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.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
FormatProcessor	added preview
IdentityHashMap
remove(Object, Object)	added
replace(Object, Object, Object)	added
LinkedHashMap	- implements Map + implements SequencedMap
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
removeFirst()	added
removeLast()	added
reversed()	added
LinkedList
reversed()	added
Locale
availableLocales()	added
caseFoldLanguageTag(String)	added
TreeMap
putFirst(Object, Object)	added
putLast(Object, Object)	added
TreeSet
addFirst(Object)	added
addLast(Object)	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
DecapsulateException	added
KEM.Decapsulator	added
KEM.Encapsulated	added
KEM.Encapsulator	added
KEM	added
KEMSpi.DecapsulatorSpi	added
KEMSpi.EncapsulatorSpi	added
KEMSpi	added
javax.net.ssl
KeyManagerFactory
getDefaultAlgorithm()	+ final
SSLParameters
getNamedGroups()	added
setNamedGroups(String[])	added
TrustManagerFactory
getDefaultAlgorithm()	+ final
java.compiler
javax.lang.model.element
TypeElement
isUnnamed()	added preview
VariableElement
isUnnamed()	added preview
javax.lang.model.util
Elements
isCanonicalConstructor(ExecutableElement)	added
isCompactConstructor(ExecutableElement)	added
javax.lang.model
SourceVersion
RELEASE_20	added
RELEASE_21	added
java.desktop
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
javax.swing.text
DefaultEditorKit
beginLineUpAction	added
endLineDownAction	added
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
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 21.0.1+12-LTS-tem and 19.0.2+7-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.