Print all unique words of a String

Write a function that takes a String as an argument and prints all unique words in it.
Examples:

Input : Java is great. Grails is also great
Output : Java
         Grails
         also

The idea is to use map to keep track of words already occurred. But first, we have to extract all words from a String, as a string may contain many sentences with punctuation marks.
For extracting words from a String, refer Extracting each word from a String.
Python: The idea is to use a Dictionary for calculating the count of each word. But first, we have to extract all words from a String because a string may contain punctuation marks. This is done using regex or regular expression. The word which has count 1 in the dictionary is a unique word.

Java

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// Java program to print unique words
// from a string
  
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Test 
{
    // Prints unique words in a string
    static void printUniquedWords(String str)
    {
        // Extracting words from string
        Pattern p = Pattern.compile("[a-zA-Z]+");
        Matcher m = p.matcher(str);
          
        // Map to store count of a word
        HashMap<String, Integer> hm = new HashMap<>();
          
        // if a word found
        while (m.find()) 
        {
            String word = m.group();
              
            // If this is first occurrence of word
            if(!hm.containsKey(word))
                hm.put(word, 1);
            else
                // increment counter of word
                hm.put(word, hm.get(word) + 1);
              
        }
          
        // Traverse map and print all words whose count
        // is  1
        Set<String> s = hm.keySet();
        Iterator<String> itr = s.iterator();
  
        while(itr.hasNext())
        {
            String w = itr.next();
              
            if (hm.get(w) == 1)
                System.out.println(w);
        }    
    }
      
    // Driver Method
    public static void main(String[] args) 
    {
        String str = "Java is great. Grails is also great";
        printUniquedWords(str);
    }
}

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Python

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# Python program to print unique word
# in a string.
# Using re (Regular Expression module)
# It is used here to match a pattern 
# in the given string
import re
  
# Declare a dictionary 
dict = {} 
  
# Method to check whether the word 
# exists in dictionary or not 
def uniqueWord(Word): 
  
    if Word in dict
  
        # If the word exists in dictionary then 
        # simply increase its count 
        dict[words] += 1
  
    else
  
        # If the word does not exists in 
        # dictionary update the dictionary
        # and make its count 1 
        dict.update({words: 1}) 
  
# Driver code
if __name__ == '__main__'
      
    string = "Java is great. Grails is also great"
      
    # re.split() method is used to split
    # all the words in a string seperated
    # by non-alphanumeric characters (\W)
    ListOfWords = re.split("[\W]+", string)
  
    # Extract each word from ListOfWords 
    # and pass it to the method uniqueWord() 
    for words in ListOfWords: 
        uniqueWord(words) 
  
    # Iterate over dictionary if the value
    # of the key is 1, then print the element 
    for elements in dict
        if dict[elements] == 1
            print(elements) 

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Output: 

Java
Grails
also

This article is contributed by Gaurav Ahirwar and Gaurav Miglani. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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