// JDK16以前
private static void oldInstanceOf(Object x) {
    if (x instanceof String) {
        String s = (String) x;
        System.out.println(s);
    }
}
// JDK16或之后啟用instanceof下的Type模式
private static void newInstanceOfTypePattern(Object x) {
    if (x instanceof String s) {
        System.out.println(s);
    }
}

// DEMO-1
private static void switchTypePattern(String s) {
    switch (s) {
        case null -> System.out.println("NULL");
        case "Foo", "Bar" -> System.out.println("Foo or Bar");
        default -> System.out.println("Default");
    }
}
// DEMO-2
interface Shape{}
class Rectangle implements Shape{}
class Triangle implements Shape{
    public int calculateArea(){
        return 200;
    }
}
private static void switchTypePatternForShape(Shape shape) {
    switch (shape) {
        case null:
            break;
        case Rectangle r:
            System.out.printf("Rectangle[%s]\n", r);
            break;
        case Triangle t:
            if (t.calculateArea() > 100) {
                System.out.printf("Large triangle[%s]\n", t);
            }
        default:
            System.out.println("Default shape");
    }
}
// DEMO-3 patterns in labels
private static void switchTypeForLabels(Object x) {
    String formatted = switch (x) {
        case Integer i -> String.format("int => %d", i);
        case Long l -> String.format("long => %d", l);
        case Double d -> String.format("double => %f", d);
        case String s -> String.format("string => %s", s);
        default -> x.toString();
    };
}

// DEMO-1
record Point(int x,int y){}
private static void printSum(Object o){
    if (o instanceof Point(int x,int y)){
        System.out.println(x + y);
    }
}

// DEMO-2
record Holder<T>(T target){}
// 擦除后
private void convert(Holder<Object> holder){
    if (Objects.nonNull(holder) && holder instanceof Holder<Object>(String target)) {
        System.out.printf("string => %s\n", target);
    }
}
// 非擦除
private <T> void convert(Holder<T> holder){
    if (Objects.nonNull(holder) && holder instanceof Holder<T>(String target)) {
        System.out.printf("string => %s\n", target);
    }
}

// DEMO-3
sealed interface I permits C, D {}
final class C implements I {}
final class D implements I {}
Second<I,I> second;
private void recordSwitch() {
    second = new Second<>(new D(), new C());
    // second = new Second<>(new C(), new D());
    switch (second) {
        case Second<I, I>(C c,D d) -> System.out.printf("c => %s,d => %s", c, d);
        case Second<I, I>(D d,C c) -> System.out.printf("d => %s,c => %s", d, c);
        default -> System.out.println("default");
    }
}

public class AllocMemoryMain {
    public static void main(String[] args) {
        new AllocMemoryMain().allocMemory();
    }
    /**
     * 分配內(nèi)存
     * struct Point {
     * int x;
     * int y;
     * } pts[10];
     */
    public void allocMemory() {
        Random random = new Random();
        // 分配本地內(nèi)存
        MemorySegment segment = MemorySegment.allocateNative(2 * 4 * 10, MemorySession.openImplicit());
        // 創(chuàng)建順序內(nèi)存布局
        SequenceLayout ptsLayout = MemoryLayout.sequenceLayout(10, MemoryLayout.structLayout(
                ValueLayout.JAVA_INT.withName("x"),
                ValueLayout.JAVA_INT.withName("y")));
        // 對(duì)內(nèi)存設(shè)置值
        VarHandle xHandle = ptsLayout.varHandle(MemoryLayout.PathElement.sequenceElement(), MemoryLayout.PathElement.groupElement("x"));
        VarHandle yHandle = ptsLayout.varHandle(MemoryLayout.PathElement.sequenceElement(), MemoryLayout.PathElement.groupElement("y"));
        for (int i = 0; i < ptsLayout.elementCount(); i++) {
            int x = i * random.nextInt(100);
            int y = i * random.nextInt(100);
            xHandle.set(segment,/* index */ (long) i,/* value to write */x); // x
            yHandle.set(segment,/* index */ (long) i,/* value to write */ y); // y
            System.out.printf("index => %d, x = %d, y = %d\n", i, x, y);
        }
        // 獲取內(nèi)存值
        int xValue = (int) xHandle.get(segment, 5);
        System.out.println("Point[5].x = " + xValue);
        int yValue = (int) yHandle.get(segment, 6);
        System.out.println("Point[6].y = " + yValue);
    }
}
// 某次執(zhí)行輸出結(jié)果
index => 0, x = 0, y = 0
index => 1, x = 79, y = 16
index => 2, x = 164, y = 134
index => 3, x = 150, y = 60
index => 4, x = 152, y = 232
index => 5, x = 495, y = 240
index => 6, x = 54, y = 162
index => 7, x = 406, y = 644
index => 8, x = 464, y = 144
index => 9, x = 153, y = 342
Point[5].x = 495
Point[6].y = 162

// 方式一：直接啟動(dòng)虛擬線程，因?yàn)槟J(rèn)參數(shù)原因這樣啟動(dòng)的虛擬線程名稱為空字符串
Thread.startVirtualThread(() -> {
    Thread thread = Thread.currentThread();
    System.out.printf("線程名稱:%s,是否虛擬線程:%s\n", thread.getName(), thread.isVirtual());
});
// 方式二：Builder模式構(gòu)建
Thread vt = Thread.ofVirtual().allowSetThreadLocals(false)
        .name("VirtualWorker-", 0)
        .inheritInheritableThreadLocals(false)
        .unstarted(() -> {
            Thread thread = Thread.currentThread();
            System.out.printf("線程名稱:%s,是否虛擬線程:%s\n", thread.getName(), thread.isVirtual());
        });
vt.start();
// 方式三：Factory模式構(gòu)建
ThreadFactory factory = Thread.ofVirtual().allowSetThreadLocals(false)
        .name("VirtualFactoryWorker-", 0)
        .inheritInheritableThreadLocals(false)
        .factory();
Thread virtualWorker = factory.newThread(() -> {
    Thread thread = Thread.currentThread();
    System.out.printf("線程名稱:%s,是否虛擬線程:%s\n", thread.getName(), thread.isVirtual());
});
virtualWorker.start();
// 可以構(gòu)建"虛擬線程池"
ExecutorService executorService = Executors.newThreadPerTaskExecutor(factory);

static final VectorSpecies<Float> SPECIES = FloatVector.SPECIES_256;
private static void vectorComputation(float[] a, float[] b, float[] c) {
    for (int i = 0; i < a.length; i += SPECIES.length()) {
        var m = SPECIES.indexInRange(i, a.length);
        var va = FloatVector.fromArray(SPECIES, a, i, m);
        var vb = FloatVector.fromArray(SPECIES, b, i, m);
        var vc = va.mul(va).add(vb.mul(vb)).neg();
        vc.intoArray(c, i, m);
    }
}
public static void main(String[] args) {
    float[] a = new float[]{1.0f, 3.0f, 2.0f};
    float[] b = {1.0f, -1.0f, 5.0f};
    float[] c = {1.0f, 6.0f, 1.0f};
    vectorComputation(a, b, c);
    System.out.println(Arrays.toString(c));
}

record Point(int i, int j) {}
enum Color { RED, GREEN, BLUE; }
private void multiTypeCase(Object o) {
    switch (o) {
        case null -> System.out.println("null");
        case String s -> System.out.println("String");
        case Color c -> System.out.println("Color: " + c.toString());
        case Point p -> System.out.println("Record class: " + p.toString());
        case int[] ia -> System.out.println("Array of ints of length" + ia.length);
        default -> System.out.println("Something else");
    }
}

private int selector(Object o) {
    return switch (o) {
        case String s -> s.length();
        case Integer i -> i;
        default -> 0;
    };
}

private void switchScope(Object o) {
    switch (o) {
        case Character c
                when c.charValue() == 7:
            System.out.println("Seven!");
            break;
        default:
            break;
    }
}

private void switchNull(Object o) {
    switch (o) {
        case null -> System.out.println("null!");
        case String s -> System.out.println("String");
        default -> System.out.println("Something else");
    }
}

record User(String name, Long id){}
record Order(String orderNo, Long id){}
record Response(User user, Order order){}
private User findUser(){
    throw new UnsupportedOperationException("findUser");
}
private Order fetchOrder(){
    throw new UnsupportedOperationException("fetchOrder");
}
private Response handle() throws ExecutionException, InterruptedException {
    try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
        Future<User> user = scope.fork(() -> findUser());
        Future<Order> order = scope.fork(() -> fetchOrder());
        scope.join();           // Join both forks
        scope.throwIfFailed();  // ... and propagate errors
        // Here, both forks have succeeded, so compose their results
        return new Response(user.resultNow(), order.resultNow());
    }
}