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Thread: Iterating through an ArrayList

  1. #1
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    Default Iterating through an ArrayList

    I have several ArrayLists with certain values stored in them and I want to check my program to check the above operators. I have tried looking at the ArrayList api and couldn't find anything that could really do what I wanted.

    Ultimately, I'm trying to code something that given user's input, it'll check
    X * Y = Z
    X / Y = Z
    X - Y = Z
    X + Y = Z
    but the problem is that I'm confused on how to make it check for all the different combinations since the .get() only iterates from 0-max size.

    Also, I know that .get() returns an Object, which I have tried to convert to an int and have it do the above but, again, it would only check the combinations when they were all in the same index.

    *edit*
    I'm also confused on how to iterate through 3 different ArrayLists
      for (int i = 0; i < list[k1].size(); i++)       //this only goes up to k1's ArrayList size
            {
            	int x = Integer.parseInt((String)list[k1].get(i));
            	if(x + y == z)                    // y and z are suppose to be like x but with list[k2] and list[k3]
            	{
            		count++;
            	}
            }

    *edit*
    I just tried using the Iterator class but I'd rather use the for loop if I could figure out a way to do the above. The below doesn't work though, it'll loop infinitely with no increasing count. It's just a general idea of what I'm trying to do.
            Iterator x = list[k1].iterator();
            Iterator y = list[k2].iterator();
            Iterator z = list[k3].iterator();
     
            int count = 0;
            int r = Integer.parseInt((String)x.next());
            int s = Integer.parseInt((String)y.next());
            int t = Integer.parseInt((String)z.next());
     
            while(x.hasNext() && y.hasNext() && z.hasNext())
            {
            	if(r + s == t)
            	{
            		count++;
            	}
            	if(r - s == t)
            	{
            		count++;
            	}
            	if(r * s == t)
            	{
            		count++;
            	}
            	if(r / s == t)
            	{
            		count++;
            	}
            }
    Last edited by Actinistia; October 29th, 2011 at 11:09 PM.


  2. #2
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    Default Re: Iterating through an ArrayList

    Hi,
    I would like to ask you to use Array List of Integer type so the declaration will be
    as follow:

    List<Integer> list= new ArrayList<Integer>();

    Then iterate it using java 5 for loop like below:
    for(Integer integerObj: list){
    //place your logic here.
    }

    bean factory
    Last edited by abani; December 18th, 2011 at 01:57 AM.

  3. #3
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    Default Re: Iterating through an ArrayList

    Quote Originally Posted by abani View Post
    Hi,
    I would like to ask you to use Array List of Integer type so the declaration will be
    as follow:

    List<Integer> list= new ArrayList<Integer>();

    Then iterate it using java 5 for loop like below:
    for(Integer integerObj: list){
    //place your logic here.
    }
    Thanks for the response. I'm not sure how to implement this sort of thing yet though. I did figure out how to do what I wanted though. It was rather simplistic and I'm kicking myself over it. Basically I had to use a nested for loop and it was easily solved. Thanks again for the input!

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