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All the major features from JDK 21 in one file
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import java.time.Duration; | |
import java.time.Instant; | |
import java.util.ArrayList; | |
import java.util.List; | |
import java.util.Random; | |
import java.util.concurrent.*; | |
import java.util.function.Supplier; | |
import java.util.stream.IntStream; | |
public class Main { | |
record Coordinate(int x, int y, int z) {} | |
private static void stringTemplates() { | |
var name = "Ola"; | |
var age = 100; | |
var str = STR.""" | |
Hejsan! Your name is \{name} and your are \{age} years old."""; | |
System.out.println(str); | |
} | |
private static void sequencedCollections() { | |
var myList = new ArrayList<>(List.of(1,2,3,4,5)); | |
System.out.printf("The list %s (reversed: %s) has the last element %s and first element %s.%n", | |
myList, myList.reversed(), myList.getLast(), myList.getFirst()); | |
myList.addFirst(0); | |
System.out.printf("List contents: %s%n", myList); | |
myList.addLast(6); | |
System.out.printf("List contents: %s%n", myList); | |
} | |
private static void virtualThreads() { | |
System.out.println("Creating and running 10k virtual threads that sleep 1 sec"); | |
try (var executor = Executors.newVirtualThreadPerTaskExecutor()) { | |
IntStream.range(0, 10_000).forEach(i -> { | |
executor.submit(() -> { | |
Thread.sleep(Duration.ofSeconds(1)); | |
return i; | |
}); | |
}); | |
} | |
System.out.println("Done creating and running virtual threads"); | |
} | |
private static void structuredConcurrency() throws InterruptedException, ExecutionException { | |
// This structured task scope cancels execution and cleans up if any exceptions are thrown. | |
try (var scope = new StructuredTaskScope.ShutdownOnFailure()) { | |
Supplier<String> supplierA = scope.fork(() -> { | |
Thread.sleep(new Random(System.currentTimeMillis()).nextInt(1000, 2000)); | |
return "Result from supplier A"; | |
}); | |
Supplier<String> supplierB = scope.fork(() -> { | |
Thread.sleep(new Random(System.currentTimeMillis()).nextInt(1000, 2000)); | |
return "Result from supplier B"; | |
}); | |
scope.join().throwIfFailed(); | |
System.out.printf("Result A=%s and B=%s%n", supplierA.get(), supplierB.get()); | |
} | |
// This structured task scope cancels execution and cleans up as soon as the first task finishes. | |
List<Callable<String>> tasks = List.of( | |
() -> { | |
Thread.sleep(new Random(System.currentTimeMillis()).nextInt(1000, 2000)); | |
return "Result from supplier A"; | |
}, | |
() -> { | |
Thread.sleep(new Random(System.currentTimeMillis()).nextInt(1000, 2000)); | |
return "Result from supplier B"; | |
} | |
); | |
var deadline = Instant.now().plusMillis(1500); | |
try (var scope = new StructuredTaskScope.ShutdownOnSuccess<String>()) { | |
for (var task : tasks) { | |
scope.fork(task); | |
} | |
String result = scope.joinUntil(deadline) | |
.result(); | |
System.out.println("Winner of the race was: " + result); | |
} catch (TimeoutException e) { // if no tasks finish within the deadline, a timeout exception is raised. | |
System.out.println("None of the tasks succeeded within the deadline"); | |
} | |
} | |
private static void recordPatterns(Object obj) { | |
switch (obj) { | |
case Coordinate(int x, int y, _) -> System.out.printf("The x and y coordinates are (%d,%d)%n", x, y); | |
case null, default -> System.out.println("Error: null or unknown object"); | |
} | |
} | |
public static void main(String[] args) throws Exception { | |
stringTemplates(); | |
sequencedCollections(); | |
recordPatterns(new Coordinate(1,2,3)); | |
structuredConcurrency(); | |
virtualThreads(); | |
} | |
} |
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