Java - 按字典順序查找下一個詞

Question

請原諒我的格式錯誤，因爲我在這裏很新。 我有一個Java任務，在這個任務中，我必須找到字典中最低的單詞，它大於掃描器給定的單詞，而不會將字符串按字典順序排列。在這個例子中，給定的單詞是「am」。我已經寫了下面的代碼，但我有問題，我會在這個問題的最後解釋。

public static void main (String[] args){ 
    Scanner s = new Scanner("I am very happy with life"); 

    String high = ""; 
    String o = "am"; 
    String curr = ""; 

    while (s.hasNext()){ 
     curr = s.next(); 
     if (curr.compareTo(high) > 0) 
      high = curr; 
    } 

    Scanner ss = new Scanner("I am very happy with life"); 

    while (ss.hasNext()){ 
     curr = ss.next(); 
     if (curr.compareTo(high) < 0 && curr.compareTo(o) > 0) 
      high = curr; 
    } 

    System.out.println(high); 
}} 

我的問題是： 我不得不寫，做計算，而不是在主程序的方法。此外，我必須使用掃描儀一次，並且無法使用相同的值初始化另一臺掃描儀。

此代碼工作正常，但我有最難的時候將其轉換爲單一的功能循環方法。

PS。對不起，愚蠢的var名稱。

Answer 1

像這樣（使用TreeSet）：

import java.util.Scanner; 
import java.util.TreeSet; 

public class LexicographicScanner { 

    private final TreeSet<String> words = new TreeSet<String>(); 

    public LexicographicScanner(final Scanner scanner) 
    { 
     while (scanner.hasNext()) 
     { 
      words.add(scanner.next()); 
     } 
     scanner.close(); 
    } 

    public String nextWord(final String word) 
    { 
     return words.higher(word); 
    } 

    public static void main(String[] args) { 
     final LexicographicScanner ls 
      = new LexicographicScanner (new Scanner("I am very happy with life")); 

     System.out.println(ls.nextWord("am")); 
     System.out.println(ls.nextWord("I")); 
     System.out.println(ls.nextWord("with")); 
    } 
} 

輸出

happy 
am 
null 

編輯

如果沒有TreeSet：

public class LexicographicScanner { 

    public static String nextWord(final Scanner scanner, final String word) 
    { 
     String higher = null, curr; 
     while (scanner.hasNext()) 
     { 
      curr = scanner.next(); 
      if (curr.compareTo(word) > 0) 
      { 
       if (higher == null || curr.compareTo(higher) < 0) 
        higher = curr; 
      } 
     } 
     return higher; 
    } 

    public static void main(String[] args) { 
     final Scanner s1 = new Scanner("I am very happy with life"); 
     final Scanner s2 = new Scanner("I am very happy with life"); 
     final Scanner s3 = new Scanner("I am very happy with life"); 
     System.out.println(nextWord(s1, "am")); 
     System.out.println(nextWord(s2, "I")); 
     System.out.println(nextWord(s3, "with")); 
     s1.close(); 
     s2.close(); 
     s3.close(); 
    } 
} 

Answer 2

提示：

String res = null; 
Scanner s = new Scanner(str); 
for each curr in s scanner { 
    if (curr greater than given 
      and (dont have res or curr is less than res)) { 
     res = curr; 
    } 
} 

Answer 3

首先提出一些要求：

1. 我尋找這個詞是不是我輸入字字典更高
2. 我尋找這個詞的詞典最低可能

因此，基本上你必須走過你的輸入句子fo字和檢查這兩個要求。這裏有一些僞代碼，我希望這有助於瞭解您的問題/此解決方案。

inputWord <= input 
currentlyHighest <= null 

for (word <= sentence) { 
    is word higher than inputWord? 
     no: discard word and analyze the next one 
     yes: go on 

    do i have a currently highest word? 
     no: save the word in currentlyHighest and analyze the next word 
     yes: go on 

    is word lower than currentlyHighest? 
     no: discard word and analyze the next one 
     yes: we have found a better match: save word in currentlyHighest and analyze the next one 
}