29/03/2017

[Java] Find most consecutively repeated character in string

Here is a simple method to find the most consecutively repeated character in a string. In my view punctuation and case should not be ignored.

The idea is simply to walk the string keeping track of the current count for the item we're evaluating. When we encounter a different character, we check if the item we were evaluating appeared more times than the current max and if so, we set it as the current max.

You can check my Gist for the code (maxRepChar) with tests:

 public static Entry maxRepChar(String s){  
     Entry max = new Entry(), curr = new Entry();  
     char c;  
   
     if(s == null || s.length() == 0) return null;  
   
     //initialize with first item in string  
     curr.count = 0;  
     curr.c = s.charAt(0);  
     max.count = 0;  
   
     for(int i = 0; i < s.length(); i++){  
       c = s.charAt(i);  
   
       /*  
       keep incrementing the current counter for the item we're evaluating now  
       as long as we have a subsequent uninterrupted stream  
       */  
       if(c == curr.c) curr.count++;  
       else{  
         /*  
         when we interrupt the stream, check if the item we're evaluating  
         appeared more times than the current maximum, if so, set it as max  
         */  
         if(curr.count > max.count){  
           max.count = curr.count;  
           max.c = curr.c;  
         }  
   
         //and reset the counter for current item  
         curr.c = c;  
         curr.count = 1;  
       }  
     }  
   
     //don't miss the case when the max run untils end of string  
     if(curr.count > max.count){  
       max.count = curr.count;  
       max.c = curr.c;  
     }  
   
     return max;  
   }  

The Entry class is simply a helper structure:

char c;
int count = 0;

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