Java Program to find maximum and minimum occurring character in a string.

public class Characters     
   
   public static void main(String[] args) {    
      String str = "grass is greener on the other side";    
      int[] freq = new int[str.length()];    
      char minChar = str.charAt(0), maxChar = str.charAt(0);    
      int i, j, min, max;            
          
      //Converts given string into character array    
      char string[] = str.toCharArray();    
          
      //Count each word in given string and store in array freq    
      for(i = 0; i < string.length; i++) {    
          freq[i] = 1;    
          for(j = i+1; j < string.length; j++) {    
              if(string[i] == string[j] && string[i] != ' ' && string[i] != '0') {    
                  freq[i]++;    
                      
                  //Set string[j] to 0 to avoid printing visited character    
                  string[j] = '0';    
              }    
          }    
      }    
          
      //Determine minimum and maximum occurring characters    
      min = max = freq[0];    
      for(i = 0; i <freq.length; i++) {    
              
          //If min is greater than frequency of a character     
          //then, store frequency in min and corresponding character in minChar    
          if(min > freq[i] && freq[i] != '0') {    
              min = freq[i];    
              minChar = string[i];    
          }    
          //If max is less than frequency of a character     
          //then, store frequency in max and corresponding character in maxChar    
          if(max < freq[i]) {    
              max = freq[i];    
              maxChar = string[i];    
          }    
      }    
          
      System.out.println("Minimum occurring character: " + minChar);    
      System.out.println("Maximum occurring character: " + maxChar);    
  }    

   
Output:

Minimum occurring character: a
Maximum occurring character: e