1. True or False – Interface types can include some full method implementations.
ID: 3728555 • Letter: 1
Question
1. True or False – Interface types can include some full method implementations.
2. True or False – If Car extends Vehicle, then Vehicle v = new Car(); is correct code.
3. True or False – UML has an arrow that represents the Java extends concept.
4. Complete the class BikePart such that it correctly implements Cost.
public interface Cost {
public double getCurrentCost();
public boolean isOnSale();
}
public class BikePart implements Cost {
private String name;
private double regularPrice, salesPrice;
private boolean onSale;
public BikePart(String n, double rp, double sp, boolean os) {
name = n; regularPrice = rp, salesPrice = sp,>
}
}
5. Why does Java include both Comparable and Comparator interfaces (instead of just providing one or the other)?
6. Consider the following class Room.
public class Room {
private String roomNumber, buildingName, capacity;
public Room() { capacity = 0; }
public Room(String rn, String bn, int c) {
roomNumber = rn, buildingName = bn, capacity = c;
}
public setRN(String rn) { roomNumber = rn; }
public String getRN() { return rn; }
… more code …
}
For TrinkleRoom that extends Room, which of the following fields should or should not be included? Explain your answer.
public class TrinkleRoom extends Room {
private String roomNumber, buildingName, capacity;
private String department;
private boolean isLab;
… more code …
}
Explanation / Answer
If you post more than 1 question, as per chegg guidelines i have to solve only 1 question.
Ques 1. True
As per the new Java rules, the methods in the interface can also have a body. So, we can implement full methods in an interface.
Ques 2. True
A variable or super class can refer to the class inheriting the super class. But it can only invoke the methods in the suer class.
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