相关疑难解决方法(0)

public class Car {

    private int maxSpeed;

    public Car(int maxSpeed) {
        this.maxSpeed = maxSpeed;
    }

    public int getMaxSpeed() {
        return maxSpeed;
    }
}

我们可以按以下方式对汽车列表进行排序

    Car carX = new Car(155);
    Car carY = new Car(140);

    List<Car> cars = new ArrayList<>();
    cars.add(carX);
    cars.add(carY);

    cars.sort(Comparator.comparing(Car::getMaxSpeed));

如果我们看到方法的签名Comparator.comparing,则输入参数类型为Function<? super T, ? extends U>

在上面的例子中,是如何Car::getMaxSpeed被转换为Function<? super T, ? extends U>而以下不编译？

  Function<Void, Integer> function = Car::getMaxSpeed;

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public interface MyFunc<T> {

    boolean func(T v1, T v2);

}

public class HighTemp {

    private int hTemp;

    HighTemp(){

    }
    public HighTemp(int ht) {
        this.hTemp = ht;
    }

    boolean sameTemp(HighTemp ht2){
         return hTemp == ht2.hTemp;
    }

     boolean lessThanTemp(HighTemp ht2){
        return hTemp < ht2.hTemp;
    }
}

class InstMethWithObjRef {

    static <T> int counter(T[] vals, MyFunc<T> f, T v){
        int count = 0;

        for (int i = 0; i < vals.length; i++) {
            if(f.func(vals[i], v)) count++;
        }
        return count;
    }
    public static void …