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Thread: object oriented program help!!!

  1. #1
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    Smile object oriented program help!!!

    client program
    so basically these is it,
    it is suppost to first

    create an array of type string as the one I did
    then create 10 rectangles with random height and width and color ( the color I couldnīt figure it out yet, but I am getting ther noe)

    then print the number of rectangles created which basically does but, in a road, which is not good, but nvm I canfix that.

    the PROBLEM I truly need help with is I am trying to let the code print all the rectangles and including their areas and perimeters

    however I try to do it, but I believe I am doing something wrong because I debugged it and it ends it at the very first try it is testing it, also I am nt sure whether If I am suppost to use the for loop like that, because I am printing the rectangles previwesly created.

    also I am required to print the information of the rectangle with the largest area, but I am not sure how to

    these is my class and then goes my client program follow by the current output


    THANK YOU!!!! honeslty I am really new at these and really appreciate some help.

     	import java.util.*;
     
    	public class Rectangle{
     	 private double width, height;
     
    	 private static String color ="white";
     
    	 private Date date;
     
    	 private  static int rectangleCreated = 0; 
     
    	 Rectangle(){ // no arg constructor that  creates a default rectangle
     
    		width =1;
    		height =1;
     
    	 rectangleCreated++;
     
    	 date: new Date();
     
    	 }
     
     
    	 Rectangle( double w, double h, String c ){ // CONSTRUCTOR
     
    	 	width = w;
     
    		height = h;
     
    		color = c;
     
    		date = new Date();
     
    		rectangleCreated++;
     
     
    		}
     
    	public static int rectangleCreated(){ 	// a method that returns number of rectangle created 
     
     
    	 return rectangleCreated;
     
    	 } 
     
     
     
    	public double getHeight(){
     
    		return height;
     
    		}
    	public void setHeight ( double h) {
     
    		height = h;
     
    		}
    	public void setWidth ( double w) {
     
    		width = w;
    		}
     
    	public static String getColor(){
     
    		return color;
    		}
     
    	public static void setColor(String c){
    		color = c;
     
    		}
    	public Date getDate(){
     
    		return date;
     
    		}
    	public void setDate ( Date d){
     
    		date = d;
     
    				}
     
     
    	public double getArea(){ // returns area
     
    			return width*height;
     
    		}
    	public double getPerimeter(){ // returns perimeter
     
    		return (2*width* height);
     
    		}
    	public String toString(){
     
    		String S;
    		S = "Rectangle width of" + width;
     
    		S =  S + "and height of" +height;
     
    		S = S + " was created on " + date.toString();
     
    		return S;
     
    			}
    				}




    import java.util.*; 
     
     
     
    public class TestRectangle{
     
    	public static void main (String[]args)
    	{
     
     String[] colors = {"White","Blue","Yellow","Red","Green"};
     
     
     Rectangle[] array = new Rectangle[10]; // rectangle of 10
     
      for(int i = 0; i < 10; i++) {
      	 Rectangle r = new Rectangle();
     
     
    	 r.setWidth((Math.random()*40)+10); 
    	 r.setHeight((Math.random()*40)+10);
     
    	// colors[r.nextString(colors.length)];
     
     
    	// print number of rectangles created
    	System.out.println(Rectangle.rectangleCreated());
    		}	 
    	 // area of rectangles created
     
     
     
     for(int i = 0; i < 10; i++) {
      	 Rectangle r = new Rectangle();
     
    	 System.out.println( r.toString()+ "has area of " + r.getArea()); //" and perimeter of" + r.getPerimeter() );
     
     
    					}
     
    		// g through the array and find the information of a rectangle with largest area.
     
     
    			  }
     
    	   }



    OUTPUT


    [COD ----jGRASP exec: java TestRectangle

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    Exception in thread "main" java.lang.NullPointerException
    at Rectangle.toString(Rectangle.java:101)
    at TestRectangle.main(TestRectangle.java:35)

    ----jGRASP wedge2: exit code for process is 1.
    ----jGRASP: operation complete.
    E][/CODE]


  2. #2
    Super Moderator jps's Avatar
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    Default Re: object oriented program help!!!

    Quote Originally Posted by Username View Post
    Exception in thread "main" java.lang.NullPointerException
    at Rectangle.toString(Rectangle.java:101)
    at TestRectangle.main(TestRectangle.java:35)
    Search java.lang.NullPointerException for details on what causes an exception of this specific type.

  3. #3
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    Default Re: object oriented program help!!!

    hi

    You again creating the object of rectangle and trying to find the area.
    Instead in the same for loop while getting the no of rectangles created, get the area and perimeter.
    System.out.println(Rectangle.rectangleCreated()+"h as area of " + r.getArea() + "and perimeter of" + r.getPerimeter() );

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