I have a huge text how i can extract the most common phrases in this text

Does anyone know the easiest way to extract phrase(for example: distributed function)from text file .

Hi everyone 

How I can search about word in more than one text file in the same time 

i have  text file and i want save the word and any punctuation associated with it and in the same file i want to remove words that are common and then keep the same formatting for the text by saving it in text file.

1. WordAnalysis analysis;
2. }
3.  void setup()
4. {
5.   analysis = new WordAnalysis();
6.    String[] lines = loadStrings("input.txt");
7.    String allText = join(lines, " ");
8.   String[] wordList = split(allText, " ");
9.  
10.   for (int i = 1; i < wordList.length; i++)
11.    {
12.       println(wordList[i]);
13. }

I wrote program and I need to save the output in text file

How i can found most frequent words in text file and save it in array.