DailyProgrammer Challenge #95 intermediate level

/*
  This is my solution for the intermediate level challenge #95
  on reddit.com/r/dailyprogrammer
  Created by Robert Allen (Unh0ly_Tigg)
*/
import java.util.Random;

public class FillerText {
    public static final int maxNumWordsPerSentence = 8;
    public static final int minNumWordsPerSentence = 3;
    public static final int minNumCharsPerWord = 1;
    public static final int maxNumCharsPerWord = 12;
    public static final boolean capitalizeSentence = true;
    public static final boolean endWithPeriods = true;
    public static final float lineBreakChance = 0.15f;
    public static final float paragraphLineBreakChance = 0.50f;

    private static final String validGenChars = "abcdefghijklmnopqrstuvwxyz";
    private Random random = new Random();
    public String randomWord(int numChars) {
        String s = "";
        for(int i = 0; i < numChars; i++)
            s += validGenChars.charAt(random.nextInt(validGenChars.length()));
        return s;
    }

    public int getRandomInt(int lower, int upper) {
        return random.nextInt(upper - lower) + lower;
    }

    public String randomSentence(int numWords) {
        String s = "";
        for(int i = 0; i < numWords; i++) {
            s += randomWord(getRandomInt(minNumCharsPerWord, maxNumCharsPerWord));
            if(i != (numWords - 1))
                s += " ";
        }
        if(capitalizeSentence)
            //  get first letter                  get rest of sentence
            s = s.substring(0, 1).toUpperCase() + s.substring(1);
        if(endWithPeriods)
            s += ".";
        return s;
    }

    public String getLineBreak() {
        String s = " ";
        if(getRandomInt(0, 100) < (100 * lineBreakChance)) {
            s += "\n";
            if(getRandomInt(0, 100) < (100 * paragraphLineBreakChance))
                s += "\n";
        }
        return s;
    }

    public static void main(String[] args) {
        FillerText filler = new FillerText();
        System.out.println(filler.randomFiller(1000));
    }

    public String randomFiller(int numWords) {
        int currentCount = 0;
        String s = "";
        while(currentCount < numWords) {
            int wordCount = getRandomInt(minNumWordsPerSentence, maxNumWordsPerSentence);
            s += randomSentence(wordCount) + getLineBreak();
            currentCount += wordCount;
        }
        return s;
    }
}