Remove Adjacent Duplicates

public class progprac {
    public static void main(String[] args) {
       String str="abbaca"; // o/p=ca
        String res="";
        for(int i=0;i<=str.length()-1;i++){
            if(!res.contains(String.valueOf(str.charAt(i)))){
                res=res+str.charAt(i);
            }else{
                res=res.replace(String.valueOf(str.charAt(i)),"");
            }
        }
        System.out.println("result="+res);

    }

}

 Using stack

import java.util.Stack;

public class progprac {
    public static void main(String[] args) {
        String str = "abbaca";
        Stack<Character> stac = new Stack<>();
        char ch[] = str.toCharArray();
        for (char c : ch) {
            if (!stac.isEmpty() && stac.peek() == c) {
                stac.pop();
            } else {
                stac.push(c);
            }
        }
        String res = "";
        for (char ch1 : stac) {
            res = res + ch1;
        }
        System.out.println(res);

    }
}