Question

Part I:

1. Create a program class named TestArrays This class should have a main() method that behaves as follows:
2. Create an integer array of size 10.
3. Using a loop, fill the elements with increments of 5, starting with 5 in the first element.
4. Using the array elements, sum the second, fifth and seventh elements.
5. Display the sum with a label.
6. Change the fourth element to 86.
7. Subtract 9 from the ninth element.
8. Using a loop, display the elements of the array.
9. Compile and execute the code to ensure correct results.
10. Don’t forget to include descriptive and detailed comments in your code!!!

Part II

1. Write a toString() method for the Vehicle class that would display the attributes of the class.
2. Create an array of 7 elements that will hold Vehicle references.
3. Using a loop, assign the first 4 elements to Vehicle objects using the null constructor.
4. Instantiate a Vehicle object with a base price of $37,000 and additional features of $400.
5. Assign the object to the 5th element of the array.
6. Assign the 6th element of the array to a Vehicle object with a base price of $24,000 and additional features of $5500.
7. Assign the 7th element of the array to a Vehicle object with a base price of $53,000 and additional features of $9000.
8. Calculate the total price for the 5th, 6th and 7th vehicles in the array.
9. Using an array, display the attributes of the objects in the array calling the toString().

Answer 1

Part 1

public class Source {
    public static void main(String[] args) {
        int[] arr = new int[10];

        for (int i = 0; i < 10; i++) {
            arr[i] = (i + 1) * 5;
        }

        int sum = arr[1] + arr[4] + arr[6];
        System.out.println("Sum of second, fifth and seventh element : " + sum);
        arr[3] = 86;
        arr[8] -= 9;

        for(int x : arr){
            System.out.print(x + " ");
        }
    }
}

Output

Sum of second, fifth and seventh element : 70
5 10 15 86 25 30 35 40 36 50 
Process finished with exit code 0

Part 2

class Vehicle {
    int basePrice, additionalFeatures;

    Vehicle() {

    }

    Vehicle(int base, int add) {
        basePrice = base;
        additionalFeatures = add;
    }

    public String toString() {
        return "Base price : " + basePrice + ", " + "Additional Features : " + additionalFeatures;
    }
}


public class Source {
    public static void main(String[] args) {
        Vehicle[] v = new Vehicle[7];

        for (int i = 0; i < 4; i++) {
            v[i] = new Vehicle();
        }

        Vehicle v5 = new Vehicle(37000, 400);
        v[4] = v5;

        v[5] = new Vehicle(24000, 5500);
        v[6] = new Vehicle(53000, 9000);

        int price = 0;
        for (int i = 4; i < 7; i++) {
            price += (v[i].basePrice + v[i].additionalFeatures);
        }

        System.out.println("Total price of fifth, sixth and seventh vehicles is : " + price);

        for (Vehicle vh : v) {
            System.out.println(vh.toString());
        }
    }
}

Output

Total price of fifth, sixth and seventh vehicles is : 128900
Base price : 0, Additional Features : 0
Base price : 0, Additional Features : 0
Base price : 0, Additional Features : 0
Base price : 0, Additional Features : 0
Base price : 37000, Additional Features : 400
Base price : 24000, Additional Features : 5500
Base price : 53000, Additional Features : 9000

Process finished with exit code 0