Station { id pk,
name,
latitude,
longitude
}

Prices { fuelTypeId fk,
stationId fk,
price
}

FuelType { 
id pk,
name
}

interface I { void print(); }

public I create() {
    return () -> { System.out.println("Hello!"); };
}

private I i = this::create;

public void test() {
    i.print();
}

public class Singleton {
    private Singleton() {}

    private static class SingletonHolder {
        private final static Singleton INSTANCE = new Singleton();
    }

    public static Singleton getInstance() {
        return SingletonHolder.INSTANCE;
    }
}