🤘🏽 👩🏾‍🎨 👩🏻‍⚖️ API qui méritent enfin d'être mises à niveau à partir de Java 8. Partie 3 🌾 🤵🏼 💂

Quelles sont les raisons de la migration vers les nouvelles versions de Java? Quelqu'un le fera à cause de nouvelles fonctionnalités telles que la langue switch

, des blocs de texte ou des documents . Quelqu'un aura besoin de nouvelles fonctionnalités intéressantes telles que des modules ou des garbage collector à faible pause . Quelqu'un le fera simplement parce qu'en mettant à jour la version Java, son programme deviendra plus rapide et consommera moins de mémoire . Mais il y a une raison de plus, non moins importante. Ce sont de nouvelles API qui vous permettront d'écrire moins de code et d'éviter de perdre du temps à rechercher la fonctionnalité souhaitée dans des bibliothèques externes. Et dans certains cas, ils rendront votre code plus rapide.

Dans les deux parties précédentes, nous avons déjà couvert 10 nouvelles API apparues dans Java 9 et versions ultérieures ( partie 1 , partie 2 ). Aujourd'hui, nous en examinerons 10 autres.

une. `Stream.toList()`

Introduit dans: Java 16

Quelle est la tâche la plus couramment utilisée Stream

en Java? Bien sûr, pour la transformation des listes: nous avons une liste sur laquelle nous devons effectuer une sorte de transformation et en renvoyer une nouvelle. Vous avez probablement vu ce modèle plusieurs fois dans votre projet:

List<T> targetList = sourceList
        .stream()
        //  
        .collect(Collectors.toList());

Cela ne veut pas dire que c'est collect(Collectors.toList())

une construction très lourde, mais je veux quand même écrire moins de code pour une opération aussi fréquente. Et dans Java 16, cela est devenu possible avec une nouvelle méthode Stream.toList()

:

List<T> targetList = sourceList
        .stream()
        //  
        .toList();

- toList()

collect(Collectors.toList())

? ? , : toList()

, collect(Collectors.toList())

, , . (, ), collect(Collectors.toList())

toList()

.

Stream.toList()

, ! , Stream.toList()

Stream.toArray()

, , Spliterator

SIZED

. Collectors.toList()

ArrayList

, .

. : , , .. . Stream

, new ArrayList<>(sourceList)

List.copyOf(sourceList)

, :

JMH-

import org.openjdk.jmh.annotations.*;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
public class ToList {

    @Param({"10", "100", "1000"})
    private int size;

    private List<Integer> sourceList;

    @Setup
    public void setup() {
        sourceList = IntStream
                .range(0, size)
                .boxed()
                .collect(Collectors.toList());
    }

    @Benchmark
    public List<Integer> newArrayList() {
        return new ArrayList<>(sourceList);
    }

    @Benchmark
    public List<Integer> toList() {
        return sourceList.stream().toList();
    }

    @Benchmark
    public List<Integer> copyOf() {
        return List.copyOf(sourceList);
    }

    @Benchmark
    public List<Integer> collectToList() {
        return sourceList.stream().collect(Collectors.toList());
    }

    @Benchmark
    public List<Integer> collectToUnmodifiableList() {
        return sourceList.stream().collect(Collectors.toUnmodifiableList());
    }
}

OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)
Intel Core i5-9500 3.00GHZ
 : -f 3 -wi 3 -w 5 -i 5 -r 5 -t 6 -jvmArgs -XX:+UseParallelGC

, Stream.toList()

collect(Collectors.toList())

, List.copyOf()

! , List.copyOf()

requireNonNull

, null

-, Stream.toList()

null

. List.copyOf()

, null

, Stream

: Spliterator

, ReferencePipeline

..

, . , filter()

:

JMH-

import org.openjdk.jmh.annotations.*;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
public class ToListFilter {

    @Param({"10", "100", "1000"})
    private int size;

    private List<Integer> sourceList;

    @Setup
    public void setup() {
        sourceList = IntStream
                .range(0, size)
                .boxed()
                .collect(Collectors.toList());
    }

    @Benchmark
    public List<Integer> toList() {
        return sourceList.stream().filter(i -> i % 2 == 0).toList();
    }

    @Benchmark
    public List<Integer> newArrayList() {
        var list = new ArrayList<Integer>();
        for (var i : sourceList) {
            if (i % 2 == 0) {
                list.add(i);
            }
        }
        return list;
    }

    @Benchmark
    public List<Integer> collectToList() {
        return sourceList.stream().filter(i -> i % 2 == 0).collect(Collectors.toList());
    }

    @Benchmark
    public List<Integer> collectToUnmodifiableList() {
        return sourceList.stream().filter(i -> i % 2 == 0).collect(Collectors.toUnmodifiableList());
    }
}

OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)
Intel Core i5-9500 3.00GHZ
 : -f 3 -wi 3 -w 5 -i 5 -r 5 -t 6 -jvmArgs -XX:+UseParallelGC

! Stream.toList()

new ArrayList()

. ? , Stream.toArray()

SpinedBuffer

, , ArrayList

. , ( chunk ). SpinedBuffer

, 100 (Integer

0 99):

ArrayList

, 1.5 , , . ArrayList

add()

, SpinedBuffer

, . , , .

: Stream.toList()

, , collect(Collectors.toList())

. ( Collectors.toList()

, downstream Collector

Collector

'). , collect(Collectors.toCollection(ArrayList::new))

.

2. `String`

: `formatted()`

, `stripIndent()`

`translateEscapes()`

: Java 15

Java 15 – , :

String str = """
        ,
        !""";

String str = String.format("""
        ,
        %s!""", user);

, ? . , . String.formatted()

, String.format()

:

String str = """
        ,
        %s!""".formatted(user);

, , , , , -, ( ), -, .

, formatted()

:

String str = ", %s!".formatted(user);

, .

, Java 15 – String.stripIndent()

, . , hello.txt

:

    ,
    !

, stripIndent()

:

String str = Files.readString(Path.of("hello.txt")).stripIndent();
System.out.println(str);

,
!

, – String.translateEscapes()

. : .

, hello.txt:

,\n!

String str = Files.readString(Path.of("hello.txt")).translateEscapes();
System.out.println(str);

,
!

3. `CharSequence.isEmpty()`

, `CharSequence.compare()`

`StringBuilder.compareTo()`

: Java 15 / Java 11

, .

, Java 1.5 , , String

isEmpty()

. length()

:

if (str.length() != 0) {
    ...
}

, Java 1.6 String.isEmpty()

- :

if (!str.isEmpty()) {
    ...
}

, String

– CharSequence

( ), - , (, default

- ). , StringBuilder

length()

:

if (stringBuilder.length() != 0) {
    ...
}

14 - : Java 15, isEmpty()

String

, CharSequence

:

if (!stringBuilder.isEmpty()) {
    ...
}

CharSequence

. equals()

: ? : CharSequence

String

, , .

, Java 11, , CharSequence.compare()

:

if (CharSequence.compare(charSeq1, charSeq2) == 0) {
    ...
}

compare()

, .

Java 11 StringBuilder

Comparable

, StringBuilder

compareTo()

:

if (stringBuilder1.compareTo(stringBuilder2) == 0) {
    ...
}

4. `Collectors.filtering()`

`Collectors.flatMapping()`

: Java 9

Collectors.groupingBy()

? , :

record Movie(String title, String genre, double rating) {
}

, :

Stream<Movie> allMovies = Stream.of(
    new Movie("", "", 7.385),
    new Movie("", "", 7.974),
    new Movie(" 2", "", 8.312),
    new Movie(" ", "", 8.33),
    new Movie(" ", "", 8.619),
    new Movie("", "", 8.363),
    new Movie("", "", 7.699)
);

Map<String, List<Movie>> groups = allMovies.collect(
    Collectors.groupingBy(Movie::genre));

groups.forEach((genre, movies) -> {
    System.out.println(genre + ":");
    movies.forEach(movie ->
        System.out.printf("    %s: %.2f%n", movie.title(), movie.rating()));
});

:
    : 8.36
:
    : 7.39
    : 7.97
     2: 8.31
:
     : 8.33
     : 8.62
:
    : 7.70

, , , , 8. ? , Stream.filter()

:

Map<String, List<Movie>> groups = allMovies
    .filter(movie -> movie.rating() > 8)
    .collect(Collectors.groupingBy(Movie::genre));

:
    : 8.36
:
     2: 8.31
:
     : 8.33
     : 8.62

: , , 8. ? : Java, Collectors.filtering()

:

Map<String, List<Movie>> groups = allMovies.collect(
    Collectors.groupingBy(Movie::genre,
        Collectors.filtering(movie -> movie.rating() > 8,
            Collectors.toList())));

groups.forEach((genre, movies) -> {
    System.out.println(genre + ":");
    if (movies.isEmpty()) {
        System.out.println("    <    8 >");
    } else {
        movies.forEach(movie ->
            System.out.printf("    %s: %.2f%n", movie.title(), movie.rating()));
    }
});

groupingBy()

, :

:
    : 8.36
:
     2: 8.31
:
     : 8.33
     : 8.62
:
    <    8 >

. :

record Movie(String title, String genre, double rating, List<String> actors) {
}

Stream<Movie> allMovies = Stream.of(
    new Movie("", "", 7.385,
        List.of("", "", "")),
    new Movie("", "", 7.974,
        List.of("", "", "")),
    new Movie(" 2", "", 8.312,
        List.of("", "", "", "")),
    new Movie(" ", "", 8.33,
        List.of("", "")),
    new Movie(" ", "", 8.619,
        List.of("", "", "", "")),
    new Movie("", "", 8.363,
        List.of("", "")),
    new Movie("", "", 7.699,
        List.of("", ""))
);

groupingBy()

, Set

? Collectors.mapping()

:

Map<String, Set<List<String>>> groups = allMovies.collect(
    Collectors.groupingBy(Movie::genre,
        Collectors.mapping(Movie::actors, Collectors.toSet())));

, , . ? Collectors.flatMapping()

, , Java 9:

Map<String, Set<String>> groups = allMovies.collect(
    Collectors.groupingBy(Movie::genre,
        Collectors.flatMapping(movie -> movie.actors().stream(),
            Collectors.toSet())));

! , :

5. `StackWalker`

: Java 9

? , ? , :

public final class MyLogger {
    public static void log(String message) {
        System.out.println(message);
    }
}

, , , , log()

. Java 8 StackTraceElement[]

, , Thread.getStackTrace()

:

public static void log(String message) {
    StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
    StackTraceElement stackTraceElement = stackTrace[2];
    String msg = stackTraceElement.getClassName() + "."
               + stackTraceElement.getMethodName() + "("
               + stackTraceElement.getFileName() + ":"
               + stackTraceElement.getLineNumber() + ") "
               + message;
    System.out.println(msg);
}

, . , ( , ), JVM Java-. , . :

@Benchmark
public String stackTrace() {
    StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
    StackTraceElement stackTraceElement = stackTrace[2];
    return stackTraceElement.getClassName() + "."
         + stackTraceElement.getMethodName() + "("
         + stackTraceElement.getFileName() + ":"
         + stackTraceElement.getLineNumber() + ")";
}

OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)
Intel Core i5-9500 3.00GHZ
 : -f 1 -wi 3 -w 3 -i 5 -r 5 -t 6

Benchmark          Mode  Cnt    Score   Error  Units
Stack.stackTrace   avgt    5  103,704 ? 1,123  us/op

104 ! ! ? : StackWalker

, Java 9. .

StackWalker

«» . , StackWalker

StackWalker.getInstance()

. StackWalker

. getInstance()

StackWalker

. .

, StackWalker

, :

forEach()

.
getCallerClass()

, ( RETAIN_CLASS_REFERENCE

).
walk()

, Stream<StackFrame>

T

, T

– . .

. log()

:

public static void log(String message) {
    String msg = StackWalker
        .getInstance()
        .walk((Stream<StackFrame> frames) -> {
            StackFrame frame = frames.skip(2).findFirst().get();
            return frame.getClassName() + "."
                 + frame.getMethodName() + "("
                 + frame.getFileName() + ":"
                 + frame.getLineNumber() + ") "
                 + message;
        });
    System.out.println(msg);
}

StackWalker

:

@Benchmark
public String stackWalker() {
    return StackWalker
        .getInstance()
        .walk(frames -> {
            StackFrame frame = frames.skip(2).findFirst().get();
            return frame.getClassName() + "."
                 + frame.getMethodName() + "("
                 + frame.getFileName() + ":"
                 + frame.getLineNumber() + ")";
        });
}

OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)
Intel Core i5-9500 3.00GHZ
 : -f 1 -wi 3 -w 3 -i 5 -r 5 -t 6

Benchmark          Mode  Cnt    Score   Error  Units
Stack.stackTrace   avgt    5  103,704 ? 1,123  us/op
Stack.stackWalker  avgt    5    2,781 ? 0,156  us/op

37 ! . , 2.8 , , .

StackWalker.walk()

Stream

, : , , -. , «», :

package org.mylogger;

public final class MyLogger {
    public enum Level {
        ERROR, WARN, INFO
    }

    public static void error(String message) {
        log(Level.ERROR, message);
    }

    public static void warn(String message) {
        log(Level.WARN, message);
    }

    public static void info(String message) {
        log(Level.INFO, message);
    }

    public static void log(Level level, String message) {
        ...
    }
}

frames.skip(2)

, log()

, error()

, warn()

, log()

, . – Stream.dropWhile()

:

public static void log(Level level, String message) {
    String msg = StackWalker
        .getInstance()
        .walk((Stream<StackFrame> frames) -> {
            StackFrame frame = frames
                .dropWhile(f -> f.getClassName().startsWith("org.mylogger"))
                .findFirst()
                .get();
            return level + " "
                 + frame.getClassName() + "."
                 + frame.getMethodName() + "("
                 + frame.getFileName() + ":"
                 + frame.getLineNumber() + ") "
                 + message;
        });
    System.out.println(msg);
}

StackWalker

?

, Java 9 . , classpath. – , . , org.example.mylib.internal

, , :

package org.example.mylib.internal;

public final class Handler {
    public static void handle() {
        ...
    }
}

Handler

, . , , ? , StackWalker.getCallerClass()

, :

package org.example.mylib.internal;

public final class Handler {
    public static void handle() {
        if (!StackWalker
            .getInstance(Option.RETAIN_CLASS_REFERENCE)
            .getCallerClass()
            .getPackageName()
            .startsWith("org.example.mylib.")) {
            throw new RuntimeException("Security error");
        }
        ...
    }
}

RETAIN_CLASS_REFERENCE

, Class . , Stream.walk()

, getCallerClass()

.

6. `System.Logger`

: Java 9

, API , Java 9. API : System.Logger

, System.LoggerFinder

System.Logger.Level

.

System.Logger

:

public final class Main {
    private static final Logger LOGGER = System.getLogger("");

    public static void main(String[] args)  {
        LOGGER.log(Level.ERROR, "Critical error!");
    }
}

. 17, 2021 6:24:57 PM org.example.Main main
SEVERE: Critical error!

System.Logger

– , , . , : , SLF4J – , Logback. Log4j API – Log4j Core. , System.Logger

– java.util.logging

, java.logging

.

SLF4J , , Log4j java.util.logging

. Log4j API SLF4J java.util.logging

. System.Logger

: , . java.util.logging

, - . , Log4j, :

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.14.1</version> <!--       -->
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.14.1</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-jpl</artifactId>
    <version>2.14.1</version>
    <scope>runtime</scope>
</dependency>

: , log4j-jpl

classpath, . Java ServiceLoader

LoggerFinder

Log4jSystemLoggerFinder

Log4j:

18:24:57.941 [main] ERROR  - Critical error!

java.logging

JRE/JDK, ( java.util.logging

).

, System.Logger

SLF4J/Logback . – , SLF4J . GitHub . Log4j – .

System.Logger

:

LOGGER.log(Level.INFO, "Information");
LOGGER.log(Level.DEBUG, "Sum of {} and {} is {}:", 2, 3, 2+3);
LOGGER.log(Level.TRACE, () -> "Lazy message");
LOGGER.log(Level.ERROR, "Log exception", new Exception());

7. `Lookup.defineHiddenClass()`

: Java 15

MethodHandles.Lookup.defineClass()

, , . , : , , ( ). , . Java 15 , .

Lookup.defineHiddenClass()

. Unsafe.defineAnonymousClass()

, , . Unsafe.defineAnonymousClass()

Java 15 deprecated for removal.

. .
. , ( Class.forName()

, ClassLoader.loadClass()

, ClassLoader.findLoadedClass()

..). - < ->/<suffix>

(, org.example.Temp/0x0000000800cb8000

).
, , , Class

( , , ClassOption.STRONG

defineHiddenClass()

).
, -XX:+UnlockDiagnosticVMOptions -XX:+ShowHiddenFrames

.

, , . :

jshell> Runnable runnable = () -> {}
runnable ==> $Lambda$26/0x0000000800c0aa00@443b7951

jshell> runnable.getClass().isHidden()
$2 ==> true

« ». int

'. javac, ByteBuddy.

- :

byte[] bytes = new ByteBuddy()
        .subclass(Object.class)
        .name("org.example.Temp")
        .defineMethod("sum", int.class, Modifier.PUBLIC)
        .withParameters(int.class, int.class)
        .intercept(new Implementation.Simple(
                MethodVariableAccess.INTEGER.loadFrom(1),
                MethodVariableAccess.INTEGER.loadFrom(2),
                Addition.INTEGER,
                MethodReturn.INTEGER))
        .make()
        .getBytes();

, -:

package org.example;
public class Temp {
    public int sum(int x, int y) {
        return x + y;
    }
}

, - , - :

Lookup lookup = MethodHandles
        .lookup()
        .defineHiddenClass(bytes, false);

//     MethodHandle  reflection
Object obj = lookup
        .findConstructor(lookup.lookupClass(), MethodType.methodType(void.class))
        .invoke();

MethodHandle sumHandle = lookup.findVirtual(lookup.lookupClass(), "sum",
        MethodType.methodType(int.class, int.class, int.class));

//   sum.   5
System.out.println(sumHandle.invoke(obj, 3, 2));

, , . :

Lookup lookup1 = MethodHandles.lookup().defineHiddenClass(bytes, false);
Lookup lookup2 = MethodHandles.lookup().defineHiddenClass(bytes, false);
Lookup lookup3 = MethodHandles.lookup().defineHiddenClass(bytes, false);
System.out.println(lookup1.lookupClass()); // class org.example.Temp/0x0000000800cb4000
System.out.println(lookup2.lookupClass()); // class org.example.Temp/0x0000000800cb4400
System.out.println(lookup3.lookupClass()); // class org.example.Temp/0x0000000800cb4800

8. `Math`

: Java 9 / Java 15

, , Java, :

int x = ...
int y = ...
long z = x * y;

Java, : int

– int

, , z

long

, . long

:

long z = (long) x * y;

, - . -, , , . -, , , . , . :

  int     long

Java 9 . Math.multiplyFull()

:

long z = Math.multiplyFull(x, y);

Java , , Java 8 Math

:

int toIntExact(long value)
int incrementExact(int a)
long incrementExact(long a)
int decrementExact(int a)
long decrementExact(long a)
int negateExact(int a)
long negateExact(long a)
int addExact(int x, int y)
long addExact(long x, long y)
int subtractExact(int x, int y)
long subtractExact(long x, long y)
int multiplyExact(int x, int y)
long multiplyExact(long x, long y)

, , – , - . ? , . , , , :

jshell> Math.abs(Integer.MIN_VALUE)
$1 ==> -2147483648

, – ? , , 2147483648 int

, . , Math.absExact()

, Java 15:

jshell> Math.absExact(Integer.MIN_VALUE)
|  Exception java.lang.ArithmeticException: Overflow to represent absolute value of Integer.MIN_VALUE
|        at Math.absExact (Math.java:1392)
|        at (#1:1)

jshell> Math.absExact(Long.MIN_VALUE)
|  Exception java.lang.ArithmeticException: Overflow to represent absolute value of Long.MIN_VALUE
|        at Math.absExact (Math.java:1438)
|        at (#2:1)

, , -11 3? ? :

jshell> -11 / 3
$1 ==> -3

jshell> -11 % 3
$2 ==> -2

, -11 = 3 * (-3) - 2

. , , Python, :

>>> -11 / 3
-4
>>> -11 % 3
1

- : -11 = 3 * (-4) + 1

. , : . Java , Python – . , Java -? Java 9 Math.floorDiv()

Math.floorMod()

:

jshell> Math.floorDiv(-11, 3)
$1 ==> -4

jshell> Math.floorMod(-11, 3)
$2 ==> 1

Java 9 Math.fma(float, float, float)

Math.fma(double, double, double)

, , a * b + c

, , :

jshell> Math.fma(2.99, 5.91, 7.1)
$1 ==> 24.7709

jshell> 2.99 * 5.91 + 7.1
$2 ==> 24.770900000000005

9. `java.io.Serial`

: Java 14

Java? , , Java-. :

public class Point {
    private static final long serialVersionUID = 1L;

    public int x;
    public int y;
}

Point

, :

var point = new Point();
point.x = 1;
point.y = 2;

var baos = new ByteArrayOutputStream();
try (var oos = new ObjectOutputStream(baos)) {
    oos.writeObject(point);
}
byte[] bytes = baos.toByteArray();

. , ? , Serializable

! ( serialVersionUID

, .)

public class Point implements Serializable {
    private static final long serialVersionUID = 1;

    public int x;
    public int y;
}

– : Serializable

, serialVersionUID

, .. , Java 14 Serial

.

, :

public class Point implements Serializable {
    @Serial
    private static final long serialVersionUID = 1;
    ...
}

, , :

public class Point {
    @Serial // Annotated member is not a part of the serialization mechanism
    private static final long serialVersionUID = 1;
    ...
}

public class Point implements Serializable {
    @Serial // Annotated member is not a part of the serialization mechanism
    private static final int serialVersionUID = 1;
    ...
}

, : serialVersionUID

, serialPersistentFields

, writeObject()

, readObject()

..

, IntelliJ IDEA. JDK 16 -Xlint:serial

. , javac

:

> javac -Xlint:serial Point.java
Point.java:6: warning: [serial] serialVersionUID must be of type long in class Point
    private static final int serialVersionUID = 1;
                             ^

, Java 17.

10. `Objects`

: `checkIndex()`

, `checkFromIndexSize()`

, `checkFromToIndex()`

: Java 9 / Java 16

, , , , . :

private static void getAt(int index, int length) {
    if (index < 0) {
        throw new IllegalArgumentException("index < 0");
    }
    if (index >= length) {
        throw new IllegalArgumentException("index >= length");
    }
    ...
}

, , :

public final class PreconditionUtils {
    public static void checkIndex(int index, int length) {
        if (index < 0) {
            throw new IllegalArgumentException("index < 0");
        }
        if (index >= length) {
            throw new IllegalArgumentException("index >= length");
        }
    }
}

Java 9 , Objects

.

Objects.checkIndex()

, [0, length)

:

jshell> Objects.checkIndex(-3, 10)
|  Exception java.lang.IndexOutOfBoundsException: Index -3 out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckIndex (Preconditions.java:70)
|        at Preconditions.checkIndex (Preconditions.java:248)
|        at Objects.checkIndex (Objects.java:372)
|        at (#1:1)

jshell> Objects.checkIndex(10, 10)
|  Exception java.lang.IndexOutOfBoundsException: Index 10 out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckIndex (Preconditions.java:70)
|        at Preconditions.checkIndex (Preconditions.java:248)
|        at Objects.checkIndex (Objects.java:372)
|        at (#2:1)

Objects.checkFromIndexSize()

, [fromIndex, fromIndex + size)

[0, length)

:

jshell> Objects.checkFromIndexSize(3, 8, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [3, 3 + 8) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromIndexSize (Preconditions.java:82)
|        at Preconditions.checkFromIndexSize (Preconditions.java:343)
|        at Objects.checkFromIndexSize (Objects.java:424)
|        at (#3:1)

jshell> Objects.checkFromIndexSize(-2, 8, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [-2, -2 + 8) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromIndexSize (Preconditions.java:82)
|        at Preconditions.checkFromIndexSize (Preconditions.java:343)
|        at Objects.checkFromIndexSize (Objects.java:424)
|        at (#4:1)

jshell> Objects.checkFromIndexSize(3, -4, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [3, 3 + -4) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromIndexSize (Preconditions.java:82)
|        at Preconditions.checkFromIndexSize (Preconditions.java:343)
|        at Objects.checkFromIndexSize (Objects.java:424)
|        at (#5:1)

, Objects.checkFromToIndex()

, [fromIndex, toIndex)

[0, length)

:

jshell> Objects.checkFromToIndex(3, 11, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [3, 11) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromToIndex (Preconditions.java:76)
|        at Preconditions.checkFromToIndex (Preconditions.java:295)
|        at Objects.checkFromToIndex (Objects.java:398)
|        at (#6:1)

jshell> Objects.checkFromToIndex(-4, 8, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [-4, 8) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromToIndex (Preconditions.java:76)
|        at Preconditions.checkFromToIndex (Preconditions.java:295)
|        at Objects.checkFromToIndex (Objects.java:398)
|        at (#7:1)

jshell> Objects.checkFromToIndex(6, 4, 10)
|  Exception java.lang.IndexOutOfBoundsException: Range [6, 4) out of bounds for length 10
|        at Preconditions.outOfBounds (Preconditions.java:64)
|        at Preconditions.outOfBoundsCheckFromToIndex (Preconditions.java:76)
|        at Preconditions.checkFromToIndex (Preconditions.java:295)
|        at Objects.checkFromToIndex (Objects.java:398)
|        at (#8:1)

, Java 16 long

:

10 API, Java 16, 9- . , Java. , Java , , (1, 2, 3, 4, 5, 6, 7, 8). Java 8 , .

...

API qui méritent enfin d'être mises à niveau à partir de Java 8. Partie 3

une. Stream.toList() (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

Introduit dans: Java 16

: Java 15

: Java 15 / Java 11

: Java 9

5. StackWalker (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

: Java 9

6. System.Logger (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

: Java 9

7. Lookup.defineHiddenClass() (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

: Java 15

8. Math (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

: Java 9 / Java 15

9. java.io.Serial (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

: Java 14

: Java 9 / Java 16

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7. `Lookup.defineHiddenClass()`

8. `Math`

9. `java.io.Serial`