COM SCI 130 – Winter 2026 Practice Midterm 1 with Full A+ Solutions (UCLA Computer Science)

Winter 2026 Midterm Practice Questions

1. UML Class Diagram
Write a full java program based on the following UML class diagram. Any details not shown in
the diagram can be omitted in your answer.




public abstract class Vehicle {​
public abstract void move(double d);​
public abstract void stop();​
public abstract void turn(double d);​
}​
​
public class Car extends Vehicle {​
private double mMileage;​
private double mSpeed;​
private Axle[] axle;​
​
@Override​
public void move(double d) { ... }​
​
@Override​
public void stop() { ... }​
​
@Override​

, public void turn(double d) { ... }​
​
public void setSpeedMPH(double d) { ... }​
public double getSpeedMPH() { ... }​
public double getSpeedKPH() { ... }​
​
private void setMileage(double d) { ... }​
}​
​
public class Bicycle extends Vehicle {​
@Override​
public void move(double d) { ... }​
​
@Override​
public void stop() { ... }​
​
@Override​
public void turn(double d) { ... }​
}​
​
public class RollerSkates extends Vehicle {​
@Override​
public void move(double d) { ... }​
​
@Override​
public void stop() { ... }​
​
@Override​
public void turn(double d) { ... }​
}​
​
public class Axle {​
private Wheel[] wheel;​
​
public void addWheel() { ... }​
public void spin() { ... }​
}​
​
public interface Wheel {​
void roll();​
}



The axle and wheel fields do not need to be private.
But m_Mileage and m_Speed have to be private as indicated by the UML diagram.