Find the three most common words in a file. WordCounts.java

gistfile1.txt

import java.util.Scanner;
import java.util.Map;
import java.util.TreeMap;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Comparator;
import java.util.Iterator;


public class WordCounts {

    public static void main(String args[]) {

        try{
        	String text = new Scanner( new File("words.txt") ).useDelimiter("\\A").next();
        	String[] words = text.toLowerCase().split("\\s+");
			Map<String, Integer> wordCounts = new HashMap<String, Integer>();

			for (String word : words) {
				Integer count = wordCounts.get(word);
				if (count == null) {
					count = 0;
				}
				wordCounts.put(word, count + 1);
			}
		
			Map sortedMap = sortByValue(wordCounts);
			//System.out.println(sortedMap);
			
			Iterator iterator = sortedMap.entrySet().iterator();
			int ii  = 0;
			while (iterator.hasNext()) {
				
					Map.Entry mapEntry = (Map.Entry) iterator.next();
					if(ii < 3){
						System.out.println("The word  " + mapEntry.getKey()
						+ " : occurs " + mapEntry.getValue() + " times");
						ii++;
					}
			}
        
        }catch(FileNotFoundException ex){
        		
        }
    }
    
    public static Map sortByValue(Map unsortedMap) {
		Map sortedMap = new TreeMap(new ValueComparator(unsortedMap));
		sortedMap.putAll(unsortedMap);
		return sortedMap;
	}
    

    
}

class ValueComparator implements Comparator {
 
	Map map;
 
	public ValueComparator(Map map) {
		this.map = map;
	}
 
	public int compare(Object keyA, Object keyB) {
		Comparable valueA = (Comparable) map.get(keyA);
		Comparable valueB = (Comparable) map.get(keyB);
		return valueB.compareTo(valueA);
	}
}

String text = new Scanner( new File("words.txt") ).useDelimiter("\A").next();
in this line of code what is the use of "\A"
Thanks