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Thread: How to check itersection of objects in on collection

  1. #1
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    Default How to check itersection of objects in on collection

    Hi to all !
    Im looking for a solution to my problem.
    Dont know how to check itersection of rects from objects in one List.
    Example: We have a Object.class;The Object has a simple method
    Rectangle getRect(){return new Rectangle(x,y,10,10)}
    We create a new List; Adding some Objects to it.
    Now the problem, how to check does the Rectangles in one list itersecting each other or not ?
    I try to create an iterator the a loop the an if statement
    Iterator<Object> i = list.iterator();
    while (i.hasNext()){
    Object o = i.next();
    if (o.getRect().itersects())
    {
    //Some code
    }
    }
    Well i dont know what to put in the intersects() method;
    Adwises ?


  2. #2
    Administrator copeg's Avatar
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    Default Re: How to check itersection of objects in on collection

    Well i dont know what to put in the intersects() method;
    Read the API for this method - it can accept a variety of parameters, one of which is another Rectangle object. So pass the other Rectangle you wish to compare.

  3. #3
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    Default Re: How to check itersection of objects in on collection

    Look at my example code , ive allready the itersects and of course i know that i need an other object.
    Ive asked about objects in one list. According to my example and using you solution it mean that ive to this if (o.getRect().itersects(o.getRect())) and this is not right because it checks itself.
    All objects are in one collection, how to chekc them ? what should be in the intersects()?

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    Default Re: How to check itersection of objects in on collection

    You've been given help already, I suggest your reply with a little more gratitude.

    The intersects() method takes an argument. You need to figure out what that argument should be. What it should be depends on your end goal, which only you know.
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  5. The Following User Says Thank You to KevinWorkman For This Useful Post:

    copeg (July 10th, 2012)

  6. #5
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    Default Re: How to check itersection of objects in on collection

    No thats not the help, becasue ive asked not about the functionality of the itersect() method.
    Okay and here is a a simple solution of my problem i found.
    Ive to use 2 itertators
    Iterator<Object> i = list.iterator();
    Iterator<Object> i = list.iterator();
    while (i.hasNext()){
          while(j.hasNext()){
                Object o1 = i.next();
                Object o2 = j.next();
                if (o1.getRect().itersects(o2.getRect()))
                 {
                 //Some code
                 }
          }
    }
    And it works! Hope this will some else.
    And some help from others
    this is more right becaouse it cheks that objects are not itersectin them self
    for( int i = 0; list.length; i++)
    {
      Rectangle current = list[i].getRect();
      for( int j = 0; list.length; j++ )
      {
         Rectangle compare = list[j];
         if( !current.equals(compare)) //you could also check to see if i!=j
           if( current.intersects(compare) )
              System.out.println( "They intersect!");
      }
    }
    Last edited by Eldarmk2; July 10th, 2012 at 09:37 AM.

  7. #6
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    Default Re: How to check itersection of objects in on collection

    That was exactly what copeg told you, to take a closer look at the intersection() method, which you were using incorrectly. Actually, I predict you'll have quite a few problems with that code.
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  8. #7
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    Default Re: How to check itersection of objects in on collection

    i know how the intersects90 work since my first java book
    The problem was that i dindt think about 2 iterators in one list.
    This code should now be correct
    Iterator<Object> i = list.iterator();
    Iterator<Object> j = list.iterator();
    while (i.hasNext()){
          Object o1 = i.hasNext();
          while(j.hasNext()){
                Object o2 = j.next();
                if (o1.getRect().itersects(o2.getRect()))
                 {
                 //Some code
                 }
          }
    }

  9. #8
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    Default Re: How to check itersection of objects in on collection

    That still is not correct. Aren't you testing this out as you go?

    Also, did you really use Object as a class name?
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  10. #9
    Administrator copeg's Avatar
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    Default Re: How to check itersection of objects in on collection

    Quote Originally Posted by Eldarmk2
    becasue ive asked not about the functionality of the itersect() method
    I beg to differ...

    Quote Originally Posted by Eldarmk2
    Well i dont know what to put in the intersects() method
    Getting answers is all about phrasing questions. Phrase them in a way that doesn't correlate with your problem, then the answer you receive will not help with your problem.

  11. #10
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    Default Re: How to check itersection of objects in on collection

    No my class is caled shape

  12. #11
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    Default Re: How to check itersection of objects in on collection

    Quote Originally Posted by copeg View Post
    I beg to differ...



    Getting answers is all about phrasing questions. Phrase them in a way that doesn't correlate with your problem, then the answer you receive will not help with your problem.
    Ok thank you

  13. #12
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    Default Re: How to check itersection of objects in on collection

    Recommended reading: Coding Horror: Rubber Duck Problem Solving
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