Function for bigrams matching

I have got a following function:

public static ArrayList<String> matchLists(ArrayList<String> ar1, ArrayList<String> ar2, ArrayList<String> ar3) {

  ArrayList<String> result = new ArrayList<String>();

  for (int i = 0; i < ar1.size(); i++) {
    for (int j = 0; j < ar2.size(); j++) {
      for (int k = 0; k < ar3.size(); k++) {

        String[] s1 = ar1.get(i).split("\\s");
        String[] s2 = ar2.get(j).split("\\s");
        String[] s3 = ar3.get(k).split("\\s");

        if (s1[1].equals(s2[0]) && s2[1].equals(s3[0])) {
          result.add(s1[0] + " " + s2[0] + " " + s3[0] + " " + s3[1]);
        }
      }
    }
  }
  return result;
}       

It takes as input 3 ArrayLists of bigrams and compares them. If the second word from the first array list matches the word from the second array list then they create a sentence.

Example:

1st Array List: he ate
2nd Array List: ate two
3rd Array List: two apples

creates a sentence he ate two apples. But this function is开发者_JAVA百科 only limited to 3 ArrayLists. I would like to make it more robust so It would accept a 2d ArrayList of strings where each single ArrayList would be a collection of bigrams and would be checking all the possible matchings from the available bigrams. Can somebody help me with that?

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A 2D ArrayList of strings would be ArrayList<ArrayList<String>>. Then you just need to change your loops to loop through all of the other ArrayLists. I'm not going to tell you how to do this (as this does look very much like homework) but you should be able to figure it out quite easily :)