Auxiliary Massive. How do you get an altercation from your daughter?

[simrah]

A list class has been established from the abstract class:

public class List {
    protected ArrayList <Transport> transports = new ArrayList();
}

Abstract class:

public abstract class Transport {
    protected String model;
    protected int price;
    protected int maxSpeed;
}

On the list, I can turn to a variable abstract class:

for (Transport transport: transports) {
    if(transport.price < 30000) {
        transport.print();
    }
}

There is a subsidiary class created by the abstract with its variables:

public class Car extends Transport {
    protected static String type = "Машина";
    protected int fuel;
    protected int fuel100km;
}

So the question is, is there any way we can use the list to the variable subsidiary class?

[magpie]

1. Title List It's obviously not a good one, because it matches the name of the interface. List package java.utilwhich could lead to confusion/consciousness.
2. In itself, the problem of the treatment from the pre-primary class directly to the fields of grades is a bad smell code (code smell) because the class of ancestors should not Depending on the characteristics of / methods defined in the flux classes.

Adjustable solution: to define in the base class some abstract/virtual method that should be redefined in descendants depending on their implementation, and to use the necessary fields of descendants in such method/methods.

public abstract class Transport {
    protected abstract boolean isOk();
public void foo() {
    for (Transport transport: transports) {
        if (transport.price < 30000 && transport.isOk()) {
            transport.print();
        }
    }    
}
public void print() {
    // печатать поля класса-предка
}

}
public class Car extends Transport {

@Override

protected boolean isOk() {

return this.fuel > 10;

}
@Override
public void print() { 
    super.print(); // напечатать поля класса-предка
    // напечатать поля данного класса-потомка
}

}

---

NECORRETEC method: check the specific type of class and result in the type of class to challenge its methods/fields.

public class Transport {

public void foo() {

for (Transport transport: transports) {

if (transport.price < 30000) {

// так НЕ НАДО делать

if (transport instanceof Car) {

Car car = (Car) transport;

car.fuel += 100500;

}

}

}

}

}