Part (a)

Write the nextTankToFill method that returns the index of the tank with lowest fuel.

Solution

public int nextTankToFill(int threshold)
{
    int tankWithLeast = 0;
    for (int i = 1; i < tanks.size(); i++)
    {
        if (tanks.get(i).getFuelLevel() < tanks.get(tankWithLeast).getFuelLevel())
        {
            tankWithLeast = i;
        }
    }
    
    if (tanks.get(tankWithLeast).getFuelLevel() <= threshold)
    {
        return tankWithLeast;
    }
    else
    {
        return filler.getCurrentIndex();
    }
}

Part (b)

Write the moveToLocation method that moves the robot to a specific tank index.

Solution

public void moveToLocation(int tankIndex)
{
    int currentIndex = filler.getCurrentIndex();
    
    if (tankIndex > currentIndex)
    {
        filler.changeDirection(FuelRobot.FORWARD);
        filler.moveForward(tankIndex - currentIndex);
    }
    else if (tankIndex < currentIndex)
    {
        filler.changeDirection(FuelRobot.BACKWARD);
        filler.moveForward(currentIndex - tankIndex);
    }
}

Key Concepts

Common Mistakes