Create a class Rectangle with instance variables length and width to
have default value of 1 for both of them. The class should have
suitable set and get methods for accessing its instance variables. The
set methods should verify that length and width are assigned a
value that is larger than 0.0 and is lesser than 20.0, Provide
suitable public methods to calculate the rectangle’s perimeter and
area. Write a suitable class "RectangleTest" to test the Rectangle
class.
What I came up with:
package rectangle;
public class Rectangle
{
private double width;
private double length;
public Rectangle()
{
width=1;
length=1;
}
public Rectangle(double width, double length)
{
this.width = width;
this.length = length;
}
public void setWidth(float width)
{
this.width = width;
}
public float getWidth()
{
return (float) width;
}
public void setLength(float length)
{
this.length = length;
}
public float getLength()
{
return (float) length;
}
public double getPerimeter()
{
return 2 * (width + length);
}
public double getArea()
{
return width * length;
}
}
package rectangle;
import java.util.Scanner;
public class RectangleTest extends Rectangle
{
public static void main(String[] args)
{
Scanner RectangleTest = new Scanner(System.in);
System.out.print("Length: ");
float lengthInput = RectangleTest.nextFloat();
System.out.print("Width: ");
float widthInput = RectangleTest.nextFloat();
Rectangle rectangle = new Rectangle (lengthInput, widthInput);
System.out.printf("Perimeter: %f%n",
rectangle.getPerimeter());
System.out.printf("Area: %f%n",
rectangle.getArea());
}
}
Code is fine, it's just I am not sure how to implement the between 0 - 20 without breaking everything and have tried different things.
I'd check it and throw an IllegalArgumentException if the value isn't valid, e.g.:
public void setLength(float length) {
if (length <= 0f || length >= 20.0f) {
throw new IllegalArgumentException("Invalid length " + length);
}
this.length = length;
}
Related
I have a servlet which accepts a rectangle xml and adds it to existing xml database. It works fine except it accepts such an xml with any amount of extra parameters as well:
<rectangle>
<width>100</width>
<height>100</height>
<someparam>param</someparam>
</rectangle>
despite the xml being the wrong format servlet returns 200 OK and adds a new rectangle to database but only taking the width and height parameters and omitting extra ones. How can I make sure that only rectangles with two parameters: width and height are accepted?
Rectangle class:
import jakarta.xml.bind.annotation.XmlAccessType;
import jakarta.xml.bind.annotation.XmlAccessorType;
import jakarta.xml.bind.annotation.XmlRootElement;
import jakarta.xml.bind.annotation.XmlType;
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(propOrder = {"width", "height"})
public class Rectangle{
private int width, height;
public Rectangle(){}
public Rectangle(int width, int height) {
this.width = width;
this.height = height;
}
public int getWidth() {
return width;
}
public int getHeight() {
return height;
}
public void setWidth(int width) {
this.width = width;
}
public void setHeight(int height) {
this.height = height;
}
public int getDiagonal(){
return (int)Math.sqrt(width * width + height * height);
}
public int getPerimeter(){
return 2 * (width + height);
}
public int getArea(){
return width * height;
}
public boolean validate(){
return width > 0 && height > 0;
}
#Override
public String toString() {
return "Rectangle [" + width + ", " + height + "]";
}
}
Unmarshalling code:
//Servlet passes request.getInputStream() as input argument
public static Rectangle streamToRectangle(InputStream input) throws UnmarshalException, JAXBException{
JAXBContext context = JAXBContext.newInstance(Rectangle.class);
Rectangle rectangle = (Rectangle) context.createUnmarshaller().unmarshal(input);
return rectangle;
}
If I have a class with four attributes and their getters and setters:
public class Shape {
private int id;
private int length;
private int width;
private int height;
Shape(int id, int length, int width, int height){
this.id = id;
this.length = length;
this.width = width;
this.height = height;
}
public int getId() {
return id;
}
public int getLength() {
return length;
}
public void setLength(int length) {
this.length = length;
}
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
}
In my main class, I have a PriorityQueue of shapes ordered by height. My question is: how can I find an object in my PriorityQueue and update its length and width?
import java.util.Comparator;
import java.util.PriorityQueue;
public class Main {
public static void main(String[] args) {
Comparator<Shape> comparator = Comparator.comparing(Shape::getHeight);
PriorityQueue<Shape> shapes = new PriorityQueue<Shape>(comparator);
shapes.add(new Shape(1,10,10,10);
shapes.add(new Shape(2,20,20,20);
shapes.add(new Shape(3,30,30,30);
}
//What I want to do is
for(each element s in shapes){
if(s.equals(shape){
//update the length and width of element s in the priority queue
}
}
}
PS: I must implement it as a PriorityQueue
public class RightAngleTriangle
{
int height;
int width;
double area;
double perimeter;
public RightAngleTriangle()
{
height = 1;
width = 1;
}
public RightAngleTriangle(int hei, int wid)
{
if(hei > 0 && wid > 0)
{
height = hei;
width = wid;
}
else
{
height = 1;
width = 1;
}
}
public double area()
{
area = height * width;
return area;
}
public double perimeter()
{
perimeter = (height * 2) + (width * 2);
return perimeter;
}
public boolean isIsosceles()
{
if(height == width)
{
return true;
}
return false;
}
public boolean largerThan(RightAngleTriangle anotherRightAngleTriangle)
{
if (area(RightAngleTriangle) > area(anotherRightAngleTriangle))
{
}
}
}
For the method largerThan() how can I make it so largerThan() returns true if and only if the area of this RightAngleTriangle is larger than the area of anotherRightAngleTriangle. I am not sure how to compare the areas because the area is calculated locally. I tried initializing area globally but I need the returned value not the initialized value.
Just as a comment largerThan() is not a constructor, is a method
now to your question
you need to call the method in the current instance and in the object passed as parameter
public boolean largerThan(RightAngleTriangle anotherRightAngleTriangle)
{
if (this.area() > anotherRightAngleTriangle.area( ))
{
//your logic
}
}
or simple doing
public boolean largerThan(RightAngleTriangle anotherRightAngleTriangle)
{
return this.area() > anotherRightAngleTriangle.area();
}
I need to take information from a file and create them into objects and put them into an array so I can compare the areas of the objects and list in the array which object has the largest area and its location in the array.
I'm confused on how I take the information from the file and create each one into a object (circle or rectangle) and then assign that object into an array after it has been created. I think my other classes are fine, I'm just stuck on finishing the driver.
Normally, I would do something like Circle c1 = new Circle(); to create a new object, but how do I do that from a file with predefined information and assign it to an array?
Data:
“CIRCLE”, 1, “blue”, true
“RECTANGLE”, 1, 2, “blue”, true
“RECTANGLE”, 10, 2, “red”, true
“CIRCLE”, 2, “green”
“RECTANGLE”
“CIRCLE”
Driver:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;
public class Driver {
public static void main(String[] args) throws FileNotFoundException {
Scanner input = new Scanner(new File("C:/Users/Charles/Desktop/GeometricObjectsData.txt"));
ArrayList<GeometricObject> list = new ArrayList<GeometricObject>();
while (input.hasNext()) {
String line = input.nextLine();
System.out.println(line);
}
}
}
GeometricObject:
public abstract class GeometricObject {
//class variables
private String color;
private boolean filled;
//constructors
public GeometricObject() {
super();
color = "white";
filled = false;
}
public GeometricObject(String color, boolean filled) {
super();
this.color = color;
this.filled = filled;
}
//mutators
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public boolean isFilled() {
return filled;
}
public void setFilled(boolean filled) {
this.filled = filled;
}
//user-defined methods
public abstract double getArea();
public abstract double getPerimeter();
#Override
public String toString() {
return super.toString() + " \tColor=" + this.getColor() + " \tFilled=" + this.isFilled();
}
}
Circle:
public class Circle extends GeometricObject {
//class variables
private double radius;
//constructors
public Circle() {
super();
radius = 1;
}
public Circle(double radius, String color, boolean filled) {
super(color, filled);
this.radius = radius;
}
//mutators
public double getRadius() {
return radius;
}
public void setRadius(double radius) {
this.radius = radius;
}
//user-defined methods
#Override
public double getArea() {
//area of a circle
return (radius * radius * Math.PI);
}
#Override
public double getPerimeter() {
//perimeter of a circle
return (2 * radius * Math.PI);
}
#Override
public String toString() {
return super.toString() + "\nCircle: Radius=" + this.getRadius();
}
}
Rectangle:
public class Rectangle extends GeometricObject {
//class variables
private double height;
private double width;
//constructors
public Rectangle() {
super();
height = 1;
width = 1;
}
public Rectangle(double height, double width, String color, boolean filled) {
super(color,filled);
this.height = height;
this.width = width;
}
//mutators
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
//user-defined methods
#Override
public String toString() {
return super.toString() + "\nRectangle: Height=" + this.height + "\tWidth=" + this.width;
}
#Override
public double getArea() {
return (height * width);
}
#Override
public double getPerimeter() {
return (2 * height + 2 * width);
}
}
In your text file, you have special quotes around your shape items. This will make your life more difficult, so you should change that, if possible
Example of how to make objects (from your main method):
while (input.hasNext()) {
String line = input.nextLine();
System.out.println(line);
String[] parts = line.split(",");
if (parts[0].indexOf("Circle") != -1) {
Circle c = new Circle();
// ... parse the rest of the attributes to set up your circle
} else if ... // fill in the other shape cases
}
I'm a java beginner and would like some help implementing my constructors
for example
public Class WidthLenth {
private double width;
private double length;
public WidthLength(double width, double length) {
this.width = width;
this.length = length;
}
public double getWidth() {
return width;
}
public double getLength() {
return length;
}
and in another class
public Class Rectangle {
private WidthLength widthLength <-- there is a uni-directional relationship here
private String color
I need to the constructor to be in this format
public Rectangle(double width, double length, String color) {
}
So the method
public getWidthLenth() {
}
would work.
how would I implement this constructor?
You just create a new object of WidthLength in the constructor.
public Rectangle(double width, double length, String col)
{
widthLength = new WidthLength(width, length);
color = col;
}
try this:
public Rectangle(double width, double length, String color) {
this.widthLength = new WidthLength(width, length);
this.color = color;
}
public WidthLength getWidthLength() {
return this.widthLength;
}