public class DuplicateWord {    
    public static void main(String[] args) {    
        String string = "Big black bug bit a big black dog on his big black nose";    
        int count;              
        //Converts the string into lowercase
        string = string.toLowerCase();            
        //Split the string into words using built-in function
        String words[] = string.split(" ");             
        System.out.println("Duplicate words in a given string : ");     
        for(int i = 0; i < words.length; i++) {    
          count = 1;    
          for(int j = i+1; j < words.length; j++) {    
            if(words[i].equals(words[j])) {    
            count++;    
            //Set words[j] to 0 to avoid printing visited word
            words[j] = "0";    
            }    
            }                
            //Displays the duplicate word if count is greater than 1
            if(count > 1 && words[i] != "0")    
                System.out.println(words[i]);    
        }    
    }    
}