Removing duplicate values using Generic methods

import java.util.ArrayList;
import java.util.List;
/*
  by mohammed shafiq fata
  edited on 22/04/2021
*/

public class CommonElementsInTwoElementOfStringArray {

	public static void main(String[] args) {
		String[] array = { "1,2,3,4,5,8,9", "0,5,6,7" };
		String firstCellArrayElement = filterFirstElementOfArray(array);
		String secondCellArrayElement = filterSecondElementOfArray(array);
		List<String> list = compareTwoString(firstCellArrayElement, secondCellArrayElement);
		list.forEach(v -> System.out.print(v + "  "));
	}

	/*
	 * compare two string against each other
	 */
	public static List<String> compareTwoString(String s1, String s2) {
		List<String> list = new ArrayList<String>();
		for (int i = 0; i < s1.length(); i++) {
			for (int j = 0; j < s2.length(); j++) {
				if (s1.charAt(i) == s2.charAt(j)) {
					list.add("" + s1.charAt(i));
				}
			}
		}
		return list;
	}

	/*
	 * filtering commas from string first element
	 */
	public static String filterFirstElementOfArray(String... array) {
		String a = array[0];
		char[] c = a.toCharArray();
		String result = "";
		for (int i = 0; i < c.length; i++) {
			if (c[i] != ',') {
				result += c[i];
			}
		}
		return result;
	}

	/*
	 * filtering commas from string second element
	 */
	public static String filterSecondElementOfArray(String... array) {
		String a = array[1];
		char[] c = a.toCharArray();
		String result = "";
		for (int i = 0; i < c.length; i++) {
			if (c[i] != ',') {
				result += c[i];
			}
		}
		return result;
	}
}