聊聊 Java 新特性与设计模式

static factory_method.Car produce(java.lang.String);   descriptor: (Ljava/lang/String;)Lfactory_method/Car;  flags: (0x0008) ACC_STATIC  Code:    stack=7, locals=5, args_size=1      0: new #7  // class factory_method/FactoryMethodEvent      3: dup      ...      19: aload_3      20: invokevirtual #17 // Method java/lang/String.hashCode:()I      23: lookupswitch { // 2        3135580: 48        3556498: 63        default: 75      }      48: aload_3      49: ldc #23  // String fast      51: invokevirtual #25  // Method java/lang/String.equals:(Ljava/lang/Object;)Z

public class Thread implements Runnable { //JDK19(Preview)    public sealed interface Builder permits Builder.OfPlatform,        Builder.OfVirtual, ThreadBuilders.BaseThreadBuilder {        ..    }}

static <E> List <E> of (E e1, E e2, E e3) {    return ImmutableCollections.listFromTrustedArray(e1, e2, e3);}static <K, V> Map <K, V> of (K k1, V v) {    return new ImmutableCollections.Map1 < > (k1, v1);}

record FastCar(String type) implements Car { ...sealed interface Factory permits CarFactory { ...final class CarFactory {    static Vehicle produce(String type) {        var result =            switch (type) {                case "fast" - > {                    ...                    yield new FastCar(“super”);                }                case String s                when s.length() > 10 - > new SlowCar()                ...

public final class Spliterators { ...    public static <T> Iterator <T> iterator(Spliterator <<?extends T> spliterator) {        Objects.requireNonNull(spliterator);        class Adapter implements Iterator <T> , Consumer <T> {            ...        }    }}
public Collections {    ...    public static <T> ArrayList <T> list(Enumeration <T> e) { ... }

return IntegerCache.cache[i + (-IntegerCache.low)];

var engine = counter++ % 2 == 0 ? new DieselEngine() : new ElectricEngine();var fastCar = new FastCar(engine);
class FastCar {    ...    FastCar(Engine engine) {         ...    }    public void drive() {        ...        if (engine instanceof ElectricEngine ee) {            ee.checkBatteries();        }        engine.run();...sealed interface Engine {    void run();}

public class Logger {    public void log(Level level, Supplier < String > msgSupplier)    //overloaded method, Levels: OFF, SEVERE, WARNING ...

java.lang.Runnable, java.lang.Callable

java.util.Localeprivate static class Cache extends LocaleObjectCache < Object, Locale > {    private static final Cache LOCALECACHE = new Cache();

var threadPerTaskExecutor = Executors.newThreadPerTaskExecutor(threadFactory);var executor = Executors.newVirtualThreadPerTaskExecutor();threadPerTaskExecutor.execute(() - > {    while (active.get()) {        executor.submit(new ComputableTask(counter));    }})