Java Hashmaps单词分组不会返回多个ArrayList

对于一项家庭作业,我必须创建一个程序来作弊。为了做到这一点,我需要想出一种通过单词字母位置将单词分组到族中的方法。因此,例如,如果单词长度为4,他们猜测“e”,那么所有以“-e”为开头的单词都将出现在以该模式为键的哈希图的一个数组列表中,而所有以“e-”为结尾的单词都会出现在另一个以该模式为键的相同哈希图的数组列表中。我的问题是,尽管我的程序能够识别模式。它仍然返回一个空集或一个包含所有单词的ArrayList。一个多小时以来,我一直在尝试不同的东西,但似乎无法将它们正确分组。非常感谢您的帮助。这是我为这个类编写的代码,它将单词分离并添加到Hashmap中。

import java.util.ArrayList;
import java.lang.StringBuilder;
import java.util.HashMap;

public class EvilEngine 
{
HashMap<StringBuilder, ArrayList> families = new HashMap<StringBuilder, ArrayList>();
int k = 0;
ArrayList<String> currentList = new ArrayList();
StringBuilder blankPattern = new StringBuilder("");
StringBuilder newPattern = new StringBuilder("");


public void PatternMatcher(ArrayList wordlist, char guess, Integer wordlength)
{

    String word;
    int j = 0;
    int x = 0;
    int biggest = 0;
    StringBuilder longest = null;    

    while(x < wordlist.size())
    {
        int i = 0;
        int index = 0;
        for (i=0; i < wordlength; i++)
        {
            blankPattern = blankPattern.append("-");
        }
        boolean boo = false;
        newPattern = blankPattern;
        word = (String) wordlist.get(x);
        index = word.indexOf(guess);
        while (index >= 0) 
        {
            blankPattern.setCharAt(index, guess);
            newPattern = blankPattern;
            index = word.indexOf(guess, index + 1);
        }
        this.PatternCompiler(word,newPattern);
        blankPattern = blankPattern.delete(0,wordlength);
        x++;
    }
}
public void PatternCompiler (String word, StringBuilder pattern)
{
        if(!families.containsKey(pattern))
        {
            ArrayList<String> newPatternList = new ArrayList();
            newPatternList.add(word);
            families.put(pattern, newPatternList);
        }
        if (families.containsKey(pattern))
        {
            ArrayList<String> oldPatternList = new ArrayList();
            oldPatternList = families.get(pattern);
            oldPatternList.add(word);
            families.put(pattern, oldPatternList);
        }
        else {
            System.out.println("Error");
        }

}
public HashMap<StringBuilder, ArrayList> returnFamilies (){
    return families;
}
}