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;
}
I have a Canvas.java class where I have a mousemove code to track the mouse position, and have it saved to an array. If I print this code out from this class itself, the mouse position is correctly printed. However, is there any way I can access this array from another class, and have it printed still (eg. I want it to appear as a Vaadin label in MainLayout.java)? It seems that the label is only showing '[]' in place of the coordinates I want printed.
Canvas.java:
package com.vaadin.starter.beveragebuddy.ui.components;
import com.vaadin.flow.component.Component;
import com.vaadin.flow.component.HasSize;
import com.vaadin.flow.component.HasStyle;
import com.vaadin.flow.component.Tag;
import com.vaadin.flow.component.html.Label;
import com.vaadin.flow.dom.Element;
import com.vaadin.flow.dom.ElementFactory;
import elemental.json.JsonObject;
import java.util.ArrayList;
/**
* Canvas component that you can draw shapes and images on. It's a Java wrapper
* for the
* <a href="https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API">HTML5
* canvas</a>.
* <p>
* Use {#link #getContext()} to get API for rendering shapes and images on the
* canvas.
* <p>
*/
#Tag("canvas")
#SuppressWarnings("serial")
public class Canvas extends Component implements HasStyle, HasSize {
private CanvasRenderingContext2D context;
private Element element;
private boolean isDrawing = false;
private boolean mouseIsDown = false;
private double endX;
private double endY;
public static ArrayList <BoundingBox> arrayBoxes = new ArrayList<BoundingBox>();
public static ArrayList <MousePosition> mousePosArray = new ArrayList<MousePosition>();
public static ArrayList<BoundingBox> getArrayBoxes() {
return arrayBoxes;
}
public static ArrayList<MousePosition> getMousePosArray() {
return mousePosArray;
}
public static void setMousePosArray(ArrayList<MousePosition> mousePosArray) {
Canvas.mousePosArray = mousePosArray;
}
/**
* Creates a new canvas component with the given size.
* <p>
* Use the API provided by {#link #getContext()} to render graphics on the
* canvas.
* <p>
* The width and height parameters will be used for the canvas' coordinate
* system. They will determine the size of the component in pixels, unless
* you explicitly set the component's size with {#link #setWidth(String)} or
* {#link #setHeight(String)}.
*
* #param width
* the width of the canvas
* #param height
* the height of the canvas
*/
public Canvas(int width, int height) {
context = new CanvasRenderingContext2D(this);
element = getElement();
element.getStyle().set("border", "1px solid");
getElement().setAttribute("width", String.valueOf(width));
getElement().setAttribute("height", String.valueOf(height));
element.addEventListener("mousedown", event -> { // Retrieve Starting Position on MouseDown
Element boundingBoxResult = ElementFactory.createDiv();
element.appendChild(boundingBoxResult);
JsonObject evtData = event.getEventData();
double xBox = evtData.getNumber("event.x");
double yBox = evtData.getNumber("event.y");
boundingBoxResult.setAttribute("data-x", String.format("%f", xBox));
boundingBoxResult.setAttribute("data-y", String.format("%f", yBox));
BoundingBox newBox = new BoundingBox(0, xBox, yBox, 0.0, 0.0);
arrayBoxes.add(newBox);
isDrawing = true;
mouseIsDown=true;
}).addEventData("event.x").addEventData("event.y");
element.addEventListener("mouseup", event -> { // Draw Box on MouseUp
Element boundingBoxResult2 = ElementFactory.createDiv();
element.appendChild(boundingBoxResult2);
JsonObject evtData2 = event.getEventData();
endX = evtData2.getNumber("event.x");
endY = evtData2.getNumber("event.y");
boundingBoxResult2.setAttribute("end-x", String.format("%f", endX));
boundingBoxResult2.setAttribute("end-y", String.format("%f", endY));
double xcoordi = 0;
double ycoordi = 0;
double boxWidth = 0;
double boxHeight = 0;
for (int i = 0; i < arrayBoxes.size(); i++) {
arrayBoxes.get(i).setName(i + 1);
arrayBoxes.get(i).setWidth(endX, arrayBoxes.get(i).xcoordi);
arrayBoxes.get(i).setHeight(endY, arrayBoxes.get(i).ycoordi);
xcoordi = arrayBoxes.get(i).getXcoordi();
ycoordi = arrayBoxes.get(i).getYcoordi();
boxWidth = arrayBoxes.get(i).getWidth();
boxHeight = arrayBoxes.get(i).getHeight();
}
mouseIsDown=false;
context.beginPath();
context.setFillStyle("limegreen");
context.setLineWidth(2);
context.strokeRect(xcoordi, ycoordi, boxWidth, boxHeight);
context.fill();
System.out.println(arrayBoxes.toString());
}).addEventData("event.x").addEventData("event.y");
element.addEventListener("mousemove", event -> { // Retrieve Mouse Position when Moving
JsonObject mousePos = event.getEventData();
double mouseX = mousePos.getNumber("event.x");
double mouseY = mousePos.getNumber("event.y");
MousePosition currentPos = new MousePosition(mouseX, mouseY);
mousePosArray.add(0, currentPos);
setMousePosArray(mousePosArray);
System.out.println(mousePosArray.get(0));
// System.out.println(mousePosArray.get(mousePosArray.size() -1));
}).addEventData("event.x").addEventData("event.y");
}
MainLayout.java:
package com.vaadin.starter.beveragebuddy.backend;
import com.vaadin.flow.component.dependency.HtmlImport;
import com.vaadin.flow.component.html.Div;
import com.vaadin.flow.component.html.H2;
import com.vaadin.flow.component.html.Label;
import com.vaadin.flow.component.html.NativeButton;
import com.vaadin.flow.router.Route;
import com.vaadin.starter.beveragebuddy.ui.components.BoundingBox;
import com.vaadin.starter.beveragebuddy.ui.components.Canvas;
import com.vaadin.starter.beveragebuddy.ui.components.CanvasRenderingContext2D;
import com.vaadin.starter.beveragebuddy.ui.components.MousePosition;
import com.vaadin.flow.component.textfield.TextField;
import java.util.ArrayList;
#HtmlImport("frontend://styles/shared-styles.html")
#Route("")
public class MainLayout extends Div {
private CanvasRenderingContext2D ctx;
private Canvas canvas;
ArrayList<MousePosition> mousePosArray = Canvas.getMousePosArray();
ArrayList<BoundingBox> bb = Canvas.getArrayBoxes();
public MainLayout() {
H2 title = new H2("Annotation UI");
title.addClassName("main-layout__title");
canvas = new Canvas(1580, 700);
ctx = canvas.getContext();
Label label = new Label("Coordinates: " + mousePosArray);
canvas.addComponent(label);
add(label);
}
}
CanvasRenderingContext2D.java:
package com.vaadin.starter.beveragebuddy.ui.components;
import java.io.Serializable;
import java.util.ArrayList;
/**
* The context for rendering shapes and images on a canvas.
* <p>
* This is a Java wrapper for the <a href=
* "https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D">same
* client-side API</a>.
*/
public class CanvasRenderingContext2D {
private Canvas canvas;
public static ArrayList<BoundingBox> arrayBoxes = new ArrayList<BoundingBox>();
protected CanvasRenderingContext2D(Canvas canvas) {
this.canvas = canvas;
}
public void setFillStyle(String fillStyle) {
setProperty("fillStyle", fillStyle);
}
public void setStrokeStyle(String strokeStyle) {
setProperty("fillStyle", strokeStyle);
}
public void setLineWidth(double lineWidth) {
setProperty("lineWidth", lineWidth);
}
public void setFont(String font) {
setProperty("font", font);
}
public void arc(double x, double y, double radius, double startAngle,
double endAngle, boolean antiClockwise) {
callJsMethod("arc", x, y, radius, startAngle, endAngle, antiClockwise);
}
public void beginPath() {
callJsMethod("beginPath");
}
public void clearRect(double x, double y, double width, double height) {
callJsMethod("clearRect", x, y, width, height);
Canvas.arrayBoxes.clear();
}
public void closePath() {
callJsMethod("closePath");
}
/**
* Fetches the image from the given location and draws it on the canvas.
* <p>
* <b>NOTE:</b> The drawing will happen asynchronously after the browser has
* received the image.
*
* #param src
* the url of the image to draw
* #param x
* the x-coordinate of the top-left corner of the image
* #param y
* the y-coordinate of the top-left corner of the image
*/
public void drawImage(String src, double x, double y) {
runScript(String.format(
"var zwKqdZ = new Image();" + "zwKqdZ.onload = function () {"
+ "$0.getContext('2d').drawImage(zwKqdZ, %s, %s);};"
+ "zwKqdZ.src='%s';",
x, y, src));
}
/**
* Fetches the image from the given location and draws it on the canvas.
* <p>
* <b>NOTE:</b> The drawing will happen asynchronously after the browser has
* received the image.
*
* #param src
* the url of the image to draw
* #param x
* the x-coordinate of the top-left corner of the image
* #param y
* the y-coordinate of the top-left corner of the image
* #param width
* the width for the image
* #param height
* the height for the image
*/
public void drawImage(String src, double x, double y, double width,
double height) {
runScript(String.format("var zwKqdZ = new Image();"
+ "zwKqdZ.onload = function () {"
+ "$0.getContext('2d').drawImage(zwKqdZ, %s, %s, %s, %s);};"
+ "zwKqdZ.src='%s';", x, y, width, height, src));
}
public void fill() {
callJsMethod("fill");
}
public void fillRect(double x, double y, double width, double height) {
callJsMethod("fillRect", x, y, width, height);
}
public void fillText(String text, double x, double y) {
callJsMethod("fillText", text, x, y);
}
public void lineTo(double x, double y) {
callJsMethod("lineTo", x, y);
}
public void moveTo(double x, double y) {
callJsMethod("moveTo", x, y);
}
public void rect(double x, double y, double width, double height) {
callJsMethod("rect", x, y, width, height);
}
public void restore() {
callJsMethod("restore");
}
public void rotate(double angle) {
callJsMethod("rotate", angle);
}
public void save() {
callJsMethod("save");
}
public void scale(double x, double y) {
callJsMethod("scale", x, y);
}
public void stroke() {
callJsMethod("stroke");
}
public void strokeRect(double x, double y, double width, double height) {
callJsMethod("strokeRect", x, y, width, height);
}
public void strokeText(String text, double x, double y) {
callJsMethod("strokeText", text, x, y);
}
public void translate(double x, double y) {
callJsMethod("translate", x, y);
}
protected void setProperty(String propertyName, Serializable value) {
runScript(String.format("$0.getContext('2d').%s='%s'", propertyName,
value));
}
/**
* Runs the given js so that the execution order works with callJsMethod().
* Any $0 in the script will refer to the canvas element.
*/
private void runScript(String script) {
canvas.getElement().getNode().runWhenAttached(
// This structure is needed to make the execution order work
// with Element.callFunction() which is used in callJsMethod()
ui -> ui.getInternals().getStateTree().beforeClientResponse(
canvas.getElement().getNode(),
context -> ui.getPage().executeJavaScript(script,
canvas.getElement())));
}
protected void callJsMethod(String methodName, Serializable... parameters) {
canvas.getElement().callFunction("getContext('2d')." + methodName,
parameters);
}
}
BoundingBox.java:
package com.vaadin.starter.beveragebuddy.ui.components;
public class BoundingBox {
public double xcoordi = 0;
public double ycoordi = 0;
public double boxWidth = 0;
public double boxHeight = 0;
public int name;
public BoundingBox(int name, double xcoordi, double ycoordi, double boxWidth, double boxHeight) {
this.name = name;
this.xcoordi = xcoordi;
this.ycoordi = ycoordi;
this.boxWidth = boxWidth;
this.boxHeight = boxHeight;
}
public int getName() {
return name;
}
public void setName(int name) {
this.name = name;
}
public double getXcoordi() {
return xcoordi;
}
public void setXcoordi(double xcoordi) {
this.xcoordi = xcoordi;
}
public double getYcoordi() {
return ycoordi;
}
public void setYcoordi(double ycoordi) {
this.ycoordi = ycoordi;
}
public double getWidth() {
return boxWidth;
}
public void setWidth(double endX, double xcoordi) {
boxWidth = endX - xcoordi;
}
public double getHeight() {
return boxHeight;
}
public void setHeight(double endY, double ycoordi) {
boxHeight = endY - ycoordi;
}
#Override
public String toString() {
return "{" +
"Box=" + name +
", X=" + xcoordi +
", Y=" + ycoordi +
", Width=" + boxWidth +
", Height=" + boxHeight +
'}';
}
}
MousePosition.java:
package com.vaadin.starter.beveragebuddy.ui.components;
public class MousePosition {
public double mouseX;
public double mouseY;
public MousePosition(double mouseX, double mouseY) {
this.mouseX = mouseX;
this.mouseY = mouseY;
}
public double getMouseX() {
return mouseX;
}
public void setMouseX(double mouseX) {
this.mouseX = mouseX;
}
public double getMouseY() {
return mouseY;
}
public void setMouseY(double mouseY) {
this.mouseY = mouseY;
}
#Override
public String toString() {
return "MousePosition{" +
"mouseX=" + mouseX +
", mouseY=" + mouseY +
'}';
}
}
Any help is much appreciated, thank you!
Alright, with the updated code it seems your problem is that you never update the label.
You set the label text initially, but it will not be automatically updated when the array changes. What you can do is allow adding a listener to the canvas, and notify it when the value changes.
In the simplest case, a listener can be just a Java Runnable (or Supplier if you want to pass a value). My example returns a Vaadin Registration, which can be used to remove the listener by calling registration.remove().
In Canvas.java
private List<Runnable> mouseMoveListeners = new ArrayList<>(0);
...
public Registration addMouseMoveListener(Runnable listener) {
mouseMoveListeners.add(listener);
return () -> mouseMoveListeners.remove(listener);
}
And in your current mousemove listener
// Your current code in the mousemove listener
MousePosition currentPos = new MousePosition(mouseX, mouseY);
mousePosArray.add(0, currentPos);
setMousePosArray(mousePosArray);
System.out.println(mousePosArray.get(0));
// Add this to run all the listeners that have been added to the canvas
mouseMoveListeners.forEach(Runnable::run);
Then at the end of your MainLayout constructor, something like this
canvas.addMouseMoveListener(() -> label.setValue("Coordinates: " + mousePosArray));
This is untested code, but an approach similar to this should work. The point being that you somehow must notify the MainLayout when the array has changed.
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
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 have a CLickableBox class that creates boxes for me and now I need to make it so that when clicked, either an X or an O will be displayed in place. Here is the ClickableBox class.
import java.awt.event.MouseAdapter;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.Container;
public class ClickableBox extends MouseAdapter {
private int x, y, width, height;
private Color borderColor, backColor, oldColor;
private boolean drawBorder, clicked;
private Container parent;
public ClickableBox(int x, int y, int width, int height, Color borderColor,
Color backColor, boolean drawBorder, Container parent) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
this.borderColor = borderColor;
this.backColor = backColor;
this.drawBorder = drawBorder;
this.parent = parent;
}
public void draw(Graphics g) {
oldColor = g.getColor();
g.setColor(backColor);
g.fillRect(x, y, width, height);
if(drawBorder) {
g.setColor(borderColor);
g.drawRect(x, y, width, height);
}
g.setColor(oldColor);
}
public void mouseReleased(MouseEvent e) {
if(x < e.getX() && e.getX() < x + width &&
y < e.getY() && e.getY() < y + height) {
clicked = true;
parent.repaint();
}
}
public boolean isClicked() {
return clicked;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
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;
}
public Color getBorderColor() {
return borderColor;
}
public void setBorderColor(Color borderColor) {
this.borderColor = borderColor;
}
public Color getBackColor() {
return backColor;
}
public void setBackColor(Color backColor) {
this.backColor = backColor;
}
public Color getOldColor() {
return oldColor;
}
public void setOldColor(Color oldColor) {
this.oldColor = oldColor;
}
public boolean isDrawBorder() {
return drawBorder;
}
public void setDrawBorder(boolean drawBorder) {
this.drawBorder = drawBorder;
}
public void setClicked(boolean clicked) {
this.clicked = clicked;
}
}
The TicTacToeBox class should extend ClickableBox, so that each box will be a listener. It needs to be designed so that each Box object will take care of itself- it knows if it's been clicked or not, and if so, whether it's going to be showing an x or an o.
The TicTacToeBox class is what I am having trouble with. This is what I will need for my game board. Any suggestions on how to implement this, simply? Below is my TicTacToeBox so far (not much):
Some direction and/or assistance would be greatly appreciated! Thanks.
import java.awt.Color;
import java.awt.Container;
public class TicTacToeBox extends ClickableBox {
public TicTacToeBox(int x, int y, int width, int height, Color borderColor,
Color backColor, boolean drawBorder, boolean mask, Container parent)
{
super(x, y, width, height, borderColor, backColor, drawBorder, parent);
}
}
Perhaps you need to override mouseReleased() - something like this:
public void mouseReleased(MouseEvent e) {
if ( this.value == NONE ) {
if ( currentTurn == Turn.X ) {
this.value = X;
}
else {
this.value = O;
}
}
super.mouseReleased();
}
With some global currentTurn variable to keep track of whose turn it is, and a value field to represent what the current value of this box is. You'd also probably want to override draw() to make it render the "X" or "O"...