在正则表达式中查找重复词的Java程序

给定一个由字符串表示的表达式。任务是在Java的正则表达式中查找重复元素。使用映射或集合数据结构来识别句子中单词的唯一性。

例子：

Input : str = " Hi, I am Hritik and I am a programmer. "
Output: I am
Explanation: We are printing duplicate words in the given Expression.

Input : str = " Ironman is alive. "
Output: There is no Duplicate Word.
Explanation: There are no duplicate words present in the given Expression.

方法一：

1. 获取表达式。
2. 将所有单词存储在一个数组中。
3. 使用正则表达式 '\\W' 拆分单词。 （正则表达式的使用）
4. 在数组中迭代并在 Map 中存储单词和所有出现次数。
5. 现在，在地图中，如果出现次数大于 1，则我们正在打印单词。

下面是上述方法的实现：

Java

// Find Duplicate Words in a Regular Expression in Java
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // we have a expression
        String expression
            = "Hi, I am Hritik and I am a programmer";
  
        // splitting words using regex
        String[] words = expression.split("\\W");
  
        // we are creating a Map for storing
        // strings and it's occurrence"
        Map word_map = new HashMap<>();
  
        // Here we are iterating in words array and
        // increasing it's occurrence by 1.
        for (String word : words) {
  
            if (word_map.get(word) != null) {
                word_map.put(word, word_map.get(word) + 1);
            }
  
            // if the word came once then occurrence is 1.
            else {
                word_map.put(word, 1);
            }
        }
  
        // creating a keyset of word_map
        Set word_set = word_map.keySet();
  
        // We are iterating in word set
        for (String word : word_set) {
  
            // if word matched then checking occurrence
            if (word_map.get(word) > 1)
  
                // here we are printing the duplicate words
                System.out.println(word);
        }
    }
}

输出

I
am

方法二：

1. 获取表达式。
2. 将所有单词存储在一个数组中。
3. 使用正则表达式 '\\W' 拆分单词。 （正则表达式的使用）
4. 通过迭代将数组的每个单词与其他单词匹配。
5. 如果单词匹配，则在 Set 中添加单词，因为 set 删除了迭代流程添加的重复单词。
6. 最后，我们正在打印该集合。

下面是上述方法的实现：

Java

// Find Duplicate Words in a Regular Expression in Java
import java.util.*;
  
public class Main {
  
    public static void main(String[] args)
    {
        String expression
            = "Hi, I am Hritik and I am a programmer";
  
        // splitting words using regex
        String[] words = expression.split("\\W");
  
        // creating object of HashSet class implemented by
        Set set = new HashSet<>();
  
        // here we are iterating in Array
        for (int i = 0; i < words.length - 1; i++) {
  
            for (int j = 1; j < words.length; j++) {
  
                // if strings matched then adding strings in
                // Set because if we ad same string set will
                // remove one and we have only repeated
                // words.
                if (words[i].equals(words[j]) && i != j) {
                    set.add(words[i]);
                }
            }
        }
  
        // here we are printing the set
        System.out.println(set);
    }
}

输出

[I, am]