This concerns the constructionof a java class to represent a vector in two dimen
ID: 668767 • Letter: T
Question
This concerns the constructionof a java class to represent a vector in two dimensions. A vector has magnitude and direction. The following is a graphical depiction of a vector, v:
A vector can be represented by its horizontal and vertical components i.e. v=(vx,vy).
Implement the Vector class Test2K class uses such that the code been given runs without modification.
Sample I/O:
Make a selection and press return:
(0) Quit, (1) Test accessors, (2) Test scalar multiply(), (3) Test dotProduct(), (4) Test equals()
1
Enter the x component and y component (separated by a space):
5 -7
Created a Vector object with the given values for vx and vy.
Result of calling accessors: getVX()=5.00, getVY()=-7.00.
(0) Quit, (1) Test accessors, (2) Test scalar multiply(), (3) Test dotProduct(), (4) Test equals()
2
Enter the x component and y component (separated by a space):
Created Vector object: v=(vx=-3.00,vy=3.00)
Enter multiplier:
.5
New Vector: v= (vx=-1.50, vy=1.50)
(0) Quit, (1) Test accessors, (2) Test scalar multiply(), (3) Test dotProduct(), (4) Test equals()
3
Enter the x component and y component (separated by a space):
-3 3
Created Vector object: v=(vx=-3.00,vy=3.00)
Enter the x component and y component (separated by a space):
4 2
Created Vector object: v=(vx=4.00,vy=2.00)
Result of dot product of the vectors: -6.0
(0) Quit, (1) Test accessors, (2) Test scalar multiply(), (3) Test dotProduct(), (4) Test equals()
4
Enter the x component and y component (separated by a space):
12 -35
Created Vector object: v=(vx=12.00,vy=-35.00)
Enter the x component and y component (separated by a space):
12 -35
Created Vector object: v=(vx=12.00,vy=-35.00)
Testing Vector objects for equality: true
(0) Quit, (1) Test accessors, (2) Test scalar multiply(), (3) Test dotProduct(), (4) Test equals()
0
Note:
*the multiplication of vector v=(vx,vy) by a value m produces a vector v'=(mvx,mvy).
*given two vactors v=(vx,vy) and v'=(v'x,v'y) their dot product is the value of (vx x v'x, vy x v'y).
*The string class format method must be used to produced a string representation of a real number rounded to 2 decimal places e.g String.format("%.2f",4.896) produces the result "4.90".
import java.util.Scanner;
public class Test2K {
private Test2K() {}
private static int getSelection(Scanner scanner) {
System.out.println(" Make a selection and press return:");
System.out.print("(0) Quit, ");
System.out.print("(1) Test accessors, ");
System.out.println("(2) Test scalar multiply(), ");
System.out.print("(3) Test dotProduct(), ");
System.out.println("(4) Test equals() ");
return scanner.nextInt();
}
private static Vector makeVector(Scanner scanner) {
System.out.println("Enter x component and y component (separated by a space):");
return new Vector(scanner.nextInt(), scanner.nextInt());
}
public static void main(String[] args) {
final Scanner scanner = new Scanner(System.in);
int selection = getSelection(scanner);
while (selection!=0) {
if (selection==1) {
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created a Vector object with the given values for vx and vy.");
System.out.printf("Result of calling accessors: getVX()=%.2f, getVY()=%.2f. ", vOne.getVX(), vOne.getVY());
}
else if (selection==2){
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vOne);
System.out.println("Enter multiplier:");
final double multiplier = scanner.nextDouble();
final Vector vTwo = vOne.multiply(multiplier);
System.out.println("New Vector: "+vTwo);
}
else if (selection==3||selection==4) {
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vOne);
final Vector vTwo = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vTwo);
if (selection==3) {
final double result = vOne.dotProduct(vTwo);
System.out.println("Result of dot product of the vectors: "+result);
}
else { // selection==4
Object oTwo = vTwo;
System.out.println("Testing Vector objects for equality: "+vOne.equals(oTwo));
}
}
else {
System.out.println("That selection was not recognised.");
}
selection = getSelection(scanner);
}
scanner.close();
}
}
Explanation / Answer
// Vector.java
public class Vector{
double vx, vy;
public Vector(double d, double e){
vx = d;
vy = e;
}
public Object getVX(){
return vx;
}
public Object getVY(){
return vy;
}
public Vector multiply(double multiplier){
return new Vector(vx * multiplier, vy * multiplier);
}
public double dotProduct(Vector v){
return vx * v.vx + vy * v.vy;
}
}
// Test2K.java
import java.util.Scanner;
public class Test2K {
private Test2K() {}
private static int getSelection(Scanner scanner) {
System.out.print("(0) Quit, ");
System.out.print("(1) Test accessors, ");
System.out.print("(2) Test scalar multiply(), ");
System.out.print("(3) Test dotProduct(), ");
System.out.println("(4) Test equals() ");
return scanner.nextInt();
}
private static Vector makeVector(Scanner scanner) {
System.out.println("Enter x component and y component (separated by a space):");
return new Vector(scanner.nextInt(), scanner.nextInt());
}
public static void main(String[] args) {
final Scanner scanner = new Scanner(System.in);
System.out.println("Make a selection and press return:");
int selection = getSelection(scanner);
while (selection!=0) {
if (selection==1) {
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created a Vector object with the given values for vx and vy.");
System.out.printf("Result of calling accessors: getVX()=%.2f, getVY()=%.2f. ", vOne.getVX(), vOne.getVY());
}
else if (selection==2){
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vOne);
System.out.println("Enter multiplier:");
final double multiplier = scanner.nextDouble();
final Vector vTwo = vOne.multiply(multiplier);
System.out.println("New Vector: "+vTwo);
}
else if (selection==3||selection==4) {
final Vector vOne = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vOne);
final Vector vTwo = Test2K.makeVector(scanner);
System.out.println("Created Vector object: "+vTwo);
if (selection==3) {
final double result = vOne.dotProduct(vTwo);
System.out.println("Result of dot product of the vectors: "+result);
}
else { // selection==4
Object oTwo = vTwo;
System.out.println("Testing Vector objects for equality: "+vOne.equals(oTwo));
}
}
else {
System.out.println("That selection was not recognised.");
}
selection = getSelection(scanner);
}
scanner.close();
}
}