Question

How to remove non-duplicate characters from string in Java

Answer 1

import java.util.List;
import java.util.ArrayList;

public class Program {
     public static String removeNonDuplicate(String str) {
        char[] arr = str.toCharArray();
        
        List<Character> duplicateList = new ArrayList<>();
        
        for (char ch : arr) {
            if (str.indexOf(ch) != str.lastIndexOf(ch)) {
                duplicateList.add(ch);
            }
        }
        
        StringBuilder duplicateString = new StringBuilder();
        for (char ch : duplicateList) {
            duplicateString.append(ch);
        }
        
        return duplicateString.toString(); 
    }
    
    public static void main(String[] args) {
        String str = "Bubble Occurrence Mammal java";
        
        System.out.println(removeNonDuplicate(str));
    }
}



/*
run:

ubble ccurrece ammal aa

*/

 

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