请将下面代码转为 java：class Solution: def wordBreak(self, s: str, wordDict: List[str]) -> bool: import functools @functools.lru_cache(None) def back_track(s): if(not s): return True res=False for i in range(1,len(s)+1): if(s[:i] in wordDict): res=back_track(s[i:]) or res return res return back_track(s)

以下是代码转化为 Java 的版本：

import java.util.*;

class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        Map<String, Boolean> cache = new HashMap<>();
        return backTrack(s, wordDict, cache);
    }

    private boolean backTrack(String s, List<String> wordDict, Map<String, Boolean> cache) {
        if ("".equals(s)) {
            return true;
        }

        if (cache.containsKey(s)) {
            return cache.get(s);
        }

        boolean res = false;
        for (int i = 1; i <= s.length(); i++) {
            if (wordDict.contains(s.substring(0, i))) {
                res = backTrack(s.substring(i), wordDict, cache) || res;
            }
        }

        cache.put(s, res);
        return res;
    }
}