Autocomplete trie

// package whatever; // don't place package name!

import java.util.*;

class MyCode {
    public static void main (String[] args) {
    //Given an input list of words, design autocomplete function
    //to return list of words when given an input prefix

        String[] words = {"car","camp","catheter","cart","cat","crab","apple","ball","boy","bolster"};
    Trie trie = new Trie();
    for(String word: words) trie.addWord(word);

    System.out.println(trie.autocomplete(""));
    }
}


class TrieNode {
  char data;
  boolean endWord;
  HashMap<Character, TrieNode> children;

  public TrieNode(char val){
    this.data = val;
    this.endWord = false;
    this.children = new HashMap<>();
  }
}

class Trie {
  TrieNode root;

  public Trie(){
    this.root = new TrieNode(Character.MIN_VALUE); //'\u0000'
  }

  public void addWord(String word) {
    //Create pointer starting root trienode
    TrieNode curr = this.root;

    HashMap<Character, TrieNode> currChildren;
    //Loop characters of word and inserting new node for each into trie
    for(Character ch: word.toCharArray()) {
      currChildren = curr.children;
      if(!currChildren.containsKey(ch)) {
        currChildren.put(ch, new TrieNode(ch));
      }
      //Move curr node pointer to child node associated with child char
      curr = currChildren.get(ch);
    }
    curr.endWord = true;
  }

  private TrieNode getPrefixEndNode(String prefix) {
    //Create pointer starting root trienode
    TrieNode curr = this.root;

    HashMap<Character, TrieNode> currChildren;
    //Loop characters of word and inserting new node for each into trie
    for(Character ch: prefix.toCharArray()) {
      currChildren = curr.children;
      if(!currChildren.containsKey(ch)) {
        return null;
      }
      //Move curr node pointer to child node associated with child char
      curr = currChildren.get(ch);
    }
    return curr;
  }

  public ArrayList<String> autocomplete(String prefix) {
    TrieNode prefixEndNode = getPrefixEndNode(prefix);
    ArrayList<String> result = new ArrayList<>();

    if(prefixEndNode != null) {
      //DFS
      dfs(prefix, prefixEndNode, result);
    }
    return result;
  }

  private void dfs(String currPrefix, TrieNode currNode, ArrayList<String> result) {
    if(currNode.endWord) {
      result.add(currPrefix);
    }

    for(TrieNode child: currNode.children.values()) {
      dfs(currPrefix+child.data, child, result);
    }
  }

}