Need help using String Tokenizer to count the frequency of words in a string

Issue

Hey i am using Blue J and I have to use the StringTokenizer method to find the frequency of the words. I am easily able to do that but am not able to think of a method to not print repeated words.

import java.util.*;
class freq_wrd
{
 public static void main()
 {   Scanner ob=new Scanner(System.in);
     System.out.println("Enter String to read");
     String str = ob.nextLine();
     int i,j;
     StringTokenizer st = new StringTokenizer(str,"!@#$=-%^&*()_+ |}{][|<>?>,./:';");
     int n = st.countTokens();
     String a[]=new String[n];
     for(i=0;i<n;i++)
     {
        a[i]=st.nextToken();
     }

      for(i=0;i<n;i++)
      { int freq=0;
          for(j=0;j<n;j++)
          {
            if(a[i].equals(a[j]))
            freq+=1;

            }   
            System.out.println(a[i] + " = "+freq);
        }
 }
}

Solution

The string tokenizer class allows you to break a string into tokens, but it cannot help you to calculate frequencies of every word. To do this for example you can use a Map structure to store String word and Integer frequency. In the following example I'm using a TreeMap because in this way I can print words and frequencies using lexicographic order for words.

Map<String, Integer> freq = new TreeMap<>();
for (String word : words) {
    int count = freq.containsKey(word) ? freq.get(word) : 0;
    freq.put(word, count + 1);
}
for (String word: freq.keySet()) {
    System.out.println(word + " = "+ freq.get(word));
}

Answered By - dariosicily