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From: Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: What's the best way to make a cross string set?
Date: Thu, 27 Jul 2017 15:34:38 -0500
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On 7/27/2017 15:22, Eric Douglas wrote:
> On Thursday, July 27, 2017 at 3:50:08 PM UTC-4, Eric Sosman wrote:
>> recursive solution along the lines of:
>>
>> 	void tuples(List bigList, int which, String soFar) {
>> 	    if (which < bigList.size()) {
>> 	       for (Object item : bigList.get(which)) {
>> 	           tuples(bigList, which + 1, soFar + item);
>> 	       }
>> 	    } else {
>> 	        System.out.println(soFar);
>> 	    }
>> 	}
>> 	...
>> 	tuples(list1, 0, "");
>>
> 
> That doesn't make sense.  As is it doesn't compile, just says bigList.get(which) needs to return an Iterable.  I've tried modifying it but I'm not sure how it's supposed to work.
> 

import java.util.*;

public class test0 {
     public static void main(String... args) {
         List<String> list1 = Arrays.asList("a","b","c","d");
         List<String> list2 = Arrays.asList("1","2","3");
         List<String> list3 = Arrays.asList("fg","hj","kl");
         List<String> list4 = Arrays.asList("x","y");
         List<List<String>> list0 = new ArrayList<>();
         list0.add(list1);
         list0.add(list2);
         list0.add(list3);
         list0.add(list4);

         ArrayList<String> result = new ArrayList<>();
         GeneratePermutations(list0,result,0,"");

         System.out.println(result);
     }

     /* with a nod to StackOverflow */
     static void GeneratePermutations(List<List<String>>list,
      List<String> result,int depth, String current) {
         if (depth == list.size()) {
             result.add(current);
             return;
         }
         for (int i=0; i<list.get(depth).size(); i++) {
             GeneratePermutations(list,result,depth + 1,
              current + list.get(depth).get(i));
         }
     }
}



-- 

Knute Johnson