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Thread: Why does this equal that?

  1. #1
    Join Date
    Feb 2011
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    Default Why does this equal that?

    Why is it that this method returns true? I'm supposed to write an equals method that returns true if both rectangles are similar (My assumption of a "similar rectangle" is one which has the same ratio of height:length as the other rectangle).

    public class Rectangle {
    	public int width;
    	public int length;
    	public Rectangle(int width, int length){
    		this.width = width;
    		this.length = length;
    	 public static void main(String[] args) {
    		  Rectangle r = new Rectangle(2,4);
    		  Rectangle s = new Rectangle(6,13);
    		  boolean n = s.equals(r);		  
    	public boolean equals(Rectangle rectangle){
    		if((this.width / this.length) == (rectangle.width / rectangle.length))
    			return true;
    			return false;

    Shouldnt s.equals(r) return false?

  2. #2
    Administrator copeg's Avatar
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    Oct 2009
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    Default Re: Why does this equal that?

    Add some System.out.println in your equals method to check what the values of each division calculation. This will give you an indication as to why this is the case - and why are 2 rectangles equal when their width/length ratio are equal? Does that mean 6x1 is equal to 12x2?

  3. #3
    Super Moderator helloworld922's Avatar
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    Jun 2009
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    Default Re: Why does this equal that?

    In addition to Copeg's answer, you're doing integer division, which truncates to the next smallest integer (1 / 2 = 0, 4 / 3 = 1, etc.). That's why it's returning true for a 2x4 and a 6x13 rectangle.

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