What's up guys,
I keep receiving this error, cannot find symbol Circle aCircle = new Circle(); , when trying to compile the driver code my professor gave us. I'm wondering if it is because I haven't added it to my circle.java method. This is the circle driver.
package lab7;
public class CircleDriver {
public static void main(String[] args) {
Circle aCircle = new Circle();
aCircle.setColor("green");
aCircle.setRadius(10);
aCircle.display();
Double circleArea = aCircle.computeArea();
Double circumference = aCircle.computeCircumference();
System.out.println("circle area: " + circleArea);
System.out.println("circle circumference: " + circumference);
System.out.println();
}
}
This is my circle method.`
public class Circle {
private String color;
private int radius;
public Circle(String color, int radius) {
this.color = color;
this.radius = radius;
}
public Circle() {
Circle aCircle = new Circle();
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public int getRadius() {
return radius;
}
public void setRadius(int radius) {
this.radius = radius;
}
public void display() {
System.out.println("I am a circle");
System.out.println("My color is " + color);
System.out.println("My radius is " + radius);
}
public double computeArea() {
return (Math.PI * Math.pow(radius, 2));
}
public double computeCircumference() {
return (2 * Math.PI * radius);
}
}
You need to call a super() constructor when calling a circle. When you call
Circle aCircle = new Circle();
You are trying to initialize a circle in the local aspect. I think you are trying to inherit the Circle class that is already in java.
Leaving the circle constructor as
public Circle() {}
Should theoretically work to instantiate your class.
Use this code. You have mistake in constructor. I hope it will solve your issue.
In Circle.java, instead of
public Circle() {
Circle aCircle = new Circle();
}
Use this code
public Circle() {
super();
// TODO Auto-generated constructor stub
}
CircleDriver.java
public class CircleDriver {
public static void main(String[] args) {
Circle aCircle = new Circle();
aCircle.setColor("green");
aCircle.setRadius(10);
aCircle.display();
Double circleArea = aCircle.computeArea();
Double circumference = aCircle.computeCircumference();
System.out.println("circle area: " + circleArea);
System.out.println("circle circumference: " + circumference);
System.out.println();
}
}
Circle.java
public class Circle {
private String color;
private int radius;
public Circle() {
super();
// TODO Auto-generated constructor stub
}
public Circle(String color, int radius) {
super();
this.color = color;
this.radius = radius;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public int getRadius() {
return radius;
}
public void setRadius(int radius) {
this.radius = radius;
}
public void display() {
System.out.println("I am a circle");
System.out.println("My color is " + color);
System.out.println("My radius is " + radius);
}
public double computeArea() {
return (Math.PI * Math.pow(radius, 2));
}
public double computeCircumference() {
return (2 * Math.PI * radius);
}
}
Output:
I am a circle
My color is green
My radius is 10
circle area: 314.1592653589793
circle circumference: 62.83185307179586
Related
I'm java newbie, currently working on this internship task:
Given the figure objects of the following types: square, triangle, circle, trapezium. Each shape can be drawn, get its area and color. Also, the figures have unique methods, for example: return the radius, the length of the hypotenuse, the length of the side, etc.
We need to generate a random set of shapes, the number of objects in the set is also not known in advance.
After generating the array, you need to display the entire list of objects that we have, for example:
Drawing triangle, area: 8.56, hypotenuse: 6.20, color: red
Drawing square, area: 27.27, side length: 5.22, color: blue
... and so on. It is necessary to describe the task using the principles of OOP.
What I need is general advices to make my code cleaner and better, and also some help with random array part. Here is the code I currently wrote:
Shape interface:
public interface Shape {
void draw();
double getArea();
ColorEnum getColor();
}
ColorEnum enum class:
public enum ColorEnum {
RED,
ORANGE,
YELLOW,
GREEN,
BLUE,
INDIGO,
VIOLET
}
Square class:
import java.awt.*;
public class Square implements Shape {
private double side;
private Color color;
public Square(Color color, double side) {
this.color = color;
this.side = side;
}
#Override
public void draw() {
System.out.println("Drawing square, area: " + String.format("%.2f", getArea()) + ", side length: " + String.format("%.2f", getSide()) + ", color: " + getColor());
}
#Override
public double getArea() {
return side * side;
}
#Override
public Color getColor() {
return color;
}
public double getSide() {
return side;
}
}
Triangle class:
public class Triangle implements Shape {
private double side1, side2, side3;
private ColorEnum color;
public Triangle(ColorEnum color, double side1, double side2, double side3) {
this.color = color;
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
}
#Override
public void draw() {
System.out.println("Drawing triangle, area: " + String.format("%.2f", getArea()) + ", hypotenuse: " + String.format("%.2f", getHypotenuse()) + ", color: " + getColor().name().toLowerCase());
}
#Override
public double getArea() {
double p = (side1 + side2 + side3) / 2;
double s = Math.sqrt((p * (p - side1) * (p - side2) * (p - side3)));
return s;
}
#Override
public ColorEnum getColor() {
return color;
}
public double getHypotenuse() {
double hypotenuse = 0;
double[] arr = {side1, side2, side3};
for (double i : arr) {
if (hypotenuse < i) hypotenuse = i;
}
return hypotenuse;
}
}
Circle class:
public class Circle implements Shape {
private double radius;
private ColorEnum color;
public Circle(ColorEnum color, double radius) {
this.color = color;
this.radius = radius;
}
#Override
public void draw() {
System.out.println("Drawing circle, area: " + String.format("%.2f", getArea()) + ", radius: " + String.format("%.2f", getRadius()) + ", color: " + getColor().name().toLowerCase());
}
#Override
public double getArea() {
return Math.PI * Math.pow(radius, 2);
}
#Override
public ColorEnum getColor() {
return color;
}
public double getRadius() {
return radius;
}
}
Trapeze class:
public class Trapeze implements Shape {
private double base1, base2, height;
private ColorEnum color;
public Trapeze(ColorEnum color, double base1, double base2, double height) {
this.color = color;
this.base1 = base1;
this.base2 = base2;
this.height = height;
}
#Override
public void draw() {
System.out.println("Drawing trapeze, area: " + String.format("%.2f", getArea()) + ", height: " + String.format("%.2f", getHeight()) + ", color: " + getColor().name().toLowerCase());
}
#Override
public double getArea() {
return (base1 + base2) / 2 * height;
}
#Override
public ColorEnum getColor() {
return color;
}
public double getHeight() {
return height;
}
}
Now back to random array part. I need random amount of shape's with random parameters. How to nicely implement stuff like this ? Should I use factory pattern ? I accidentally found one implementation on GitHub, can you tell me is it good ?
https://github.com/Ligren/QaTestLab/blob/master/QaTestLab/src/Test/ShapeDrawing.java and https://github.com/Ligren/QaTestLab/blob/master/QaTestLab/src/Test/Start.java
So, I finished this task, and employer approved it :)
You can check final version on GitHub:
https://github.com/Wonderio619/QATestTask
the exception cannot appear, I apparently don't know where is the problem. I want to make own exception for circle radius. For example, if my input is negative value, then the exception need to appear. I made 3 classes. TestCircle.java, Circle.java and IllegalRadiusException.java
TestCircle.java
package circle;
public class TestCircle {
public static void main(String[] args) {
double newRad;
try {
Circle A = new Circle();
A.InputRadius();
A.Calculation();
newRad = A.getRadius();
A.Result();
} catch (IllegalRadiusException e) {
System.out.println(e);
}
}
}
Circle.java
package circle;
import java.util.Scanner;
public class Circle {
Scanner input = new Scanner(System.in);
private double radius;
private double area;
//this is consturctor method
public Circle() throws IllegalRadiusException {
if (radius >= 0) {
this.radius = radius;
this.area = area;
} else {
throw new IllegalRadiusException("Radius Cannot be Negative");
}
}
public void setRadius(double radius) {
this.radius = radius;
}
public double getRadius() {
return radius;
}
public void setArea(double area) {
this.area = area;
}
public double getArea() {
return area;
}
//------------------------------------------------------------//
public void Calculation() {
area = 3.142 * radius * radius;
}
public void InputRadius() {
System.out.print("Radius: ");
radius = input.nextDouble();
}
public void Result() {
System.out.println("");
System.out.println("Radius: " + radius);
System.out.println("Area: " + area);
}
}
IllegalRadiusException.java
package circle;
public class IllegalRadiusException extends Exception {
//Extra kena tambah 'extends Exception'
//WAJIB KENA LETAK untuk CREATE OWN EXCEPTION
public IllegalRadiusException() {
super();
}
public IllegalRadiusException(String message) {
super(message);
}
}
In your code, the constructor would be called only once, at the time of object's instantiation.
You've added the check for exception, only in this constructor.
For your example to work as needed, you need to throw exceptions from your InpurRadius method too, if the user enters an invalid value.
Change your method to this.
public void InputRadius() throws IllegalRadiusException {
System.out.print("Radius: ");
double entered_radius = input.nextDouble();
if (entered_radius >= 0) {
this.radius = entered_radius;
this.area = area;
} else {
throw new IllegalRadiusException("Radius Cannot be Negative");
}
}
You do not pass value to radius in constructor so it is not initialized (0). So the if statement will always pass since 0 == 0 :). Pass
public Circle(double radius) // something like this
and assign it inside constructor to radius
I am so lost I don't even know what question to ask anymore. I have this program that is supposed to be able to construct a Cylinder with parameters radius and height. Then it should be able to call various methods to get and set radius as well as output surface area and volume. I can't get passed go because I cannot put anything in my main without an error about static non static methods being used in static. I don't even know what that means. I actually copy code from others into my compiler and it gives me the same error. Do I have some setting screwed up? I know this is probably too elementary for Stack Overflow but I am desperate at this point.
public class Miller_A03Q1 {
public static void main(String[] args) {
Cylinder cylinder1 = new Cylinder(1,17);
Cylinder cylinder2 = new Cylinder(3,8);
Cylinder cylinder3 = new Cylinder(2,12);
Cylinder cylinder4 = new Cylinder (1,14);
}
public class Cylinder{
private double radius = 0.0;
private double height= 0.0;
private double area = 0.0;
private double volume=0.0;
private String shape = "cylinder";
public Cylinder(double r,double h){
this.radius = r;
System.out.print(r);
this.height = h;
System.out.print(h);
}
public double getVolume(){
double volume = 3.14 * radius * radius * height;
return volume;
}
public double getArea(){
double circumference = 3.14 * 2 * radius;
double circleArea = 3.14 * radius * radius;
double area = (2 * circleArea) + (circumference * this.height);
return area;
}
public double getRadius(){
return this.radius;
}
public double getHeight(){
return this.height;
}
public void setHeight(double h){
this.height = h;
}
public void setRadius(double r){
this.radius = r;
}
#Override
public String toString(){
return this.shape + this.radius + this.height+ this.volume + this.area;
}
}
}
Inner classes are just like any other member (well, except for enums). If you don't explicitly declare them static, they won't be, so you won't be able to access them from a static context, such as main. To make a long story short - declare you Cylinder inner class as static, and you should be OK:
public class Miller_A03Q1 {
public static void main(String[] args) {
Cylinder cylinder1 = new Cylinder(1,17);
Cylinder cylinder2 = new Cylinder(3,8);
Cylinder cylinder3 = new Cylinder(2,12);
Cylinder cylinder4 = new Cylinder (1,14);
}
public static class Cylinder{
// etc...
I don't know if you need the outer class but if you just put the main method inside the Cylinder class it compiles for me....
public class Cylinder {
private double radius = 0.0;
private double height = 0.0;
private double area = 0.0;
private double volume = 0.0;
private String shape = "cylinder";
public Cylinder(double r, double h) {
this.radius = r;
System.out.print(r);
this.height = h;
System.out.print(h);
}
public double getVolume() {
double volume = 3.14 * radius * radius * height;
return volume;
}
public double getArea() {
double circumference = 3.14 * 2 * radius;
double circleArea = 3.14 * radius * radius;
double area = (2 * circleArea) + (circumference * this.height);
return area;
}
public double getRadius() {
return this.radius;
}
public double getHeight() {
return this.height;
}
public void setHeight(double h) {
this.height = h;
}
public void setRadius(double r) {
this.radius = r;
}
#Override
public String toString() {
return this.shape + this.radius + this.height + this.volume + this.area;
}
public static void main(String[] args) {
Cylinder cylinder1 = new Cylinder(1, 17);
Cylinder cylinder2 = new Cylinder(3, 8);
Cylinder cylinder3 = new Cylinder(2, 12);
Cylinder cylinder4 = new Cylinder(1, 14);
}
}
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 am writing a program that has four classes, Circle,Rectangle,GeometricObject and my main one TestGeometricObject.
I dont understand how to read from another file such as notepad using TestGeometricObject?
I dont need help reading classes I just need help at the moment how can I connect what I have to read another file such as one on notepad, not just this program but for any program I were to write? I hope this made sense...let me know if it did not.
public class TestGeometricObject {
public static void main(String[] args) {
GeometricObject geoObject1 = new Circle();
GeometricObject geoObject2 = new Rectangle();
System.out.println("The two objects have the same area? " +
equalArea(geoObject1, geoObject2));
// Display circle
displayGeometricObject(geoObject1);
// Display rectangle
displayGeometricObject(geoObject2);
}
public static boolean equalArea(GeometricObject object1,GeometricObject object2) {
return object1.getArea() == object2.getArea();
}
public static void displayGeometricObject(GeometricObject object) {
System.out.println();
System.out.println("The area is " + object.getArea());
System.out.println("The perimeter is " + object.getPerimeter());
}
}//end main
public class Circle extends GeometricObject {
private double radius;
public Circle() {
}
public Circle(double radius) {
this.radius = radius;
}
/** Return radius */
public double getRadius() {
return radius;
}
/** Set a new radius */
public void setRadius(double radius) {
this.radius = radius;
}
/** Return area */
public double getArea() {
return radius * radius * Math.PI;
}
/** Return diameter */
public double getDiameter() {
return 2 * radius;
}
/** Return perimeter */
public double getPerimeter() {
return 2 * radius * Math.PI;
}
/* Print the circle info */
public void printCircle() {
System.out.println("The circle is created " + getDateCreated() +
" and the radius is " + radius);
}
}//end
public class Rectangle extends GeometricObject {
private double width;
private double height;
public Rectangle() {
}
public Rectangle(double width, double height) {
this.width = width;
this.height = height;
}
/** Return width */
public double getWidth() {
return width;
}
/** Set a new width */
public void setWidth(double width) {
this.width = width;
}
/** Return height */
public double getHeight() {
return height;
}
/** Set a new height */
public void setHeight(double height) {
this.height = height;
}
/** Return area */
public double getArea() {
return width * height;
}
/** Return perimeter */
public double getPerimeter() {
return 2 * (width + height);
}
}//end
public abstract class GeometricObject {
private String color = "white";
private boolean filled;
private java.util.Date dateCreated;
/** Construct a default geometric object */
protected GeometricObject() {
dateCreated = new java.util.Date();
}
/** Construct a geometric object with color and filled value */
protected GeometricObject(String color, boolean filled) {
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
/** Return color */
public String getColor() {
return color;
}
/** Set a new color */
public void setColor(String color) {
this.color = color;
}
/** Return filled. Since filled is boolean,
* the get method is named isFilled */
public boolean isFilled() {
return filled;
}
/** Set a new filled */
public void setFilled(boolean filled) {
this.filled = filled;
}
/** Get dateCreated */
public java.util.Date getDateCreated() {
return dateCreated;
}
public String toString() {
return "created on " + dateCreated + "\ncolor: " + color +
" and filled: " + filled;
}
/** Abstract method getArea */
public abstract double getArea();
/** Abstract method getPerimeter */
public abstract double getPerimeter();
}//end
To read a text file, it is common practice to use a BufferedReader wrapper and FileReader
try {
BufferedReader br = new BufferedReader(new FileReader(new File("yourFile.txt")));
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
br.close();
} catch (IOException e) {
e.printStackTrace();
}