String remove duplicate in java

To remove duplicate characters from a string in Java, you can use a combination of the charAt method and the StringBuilder.append method. Here's an example of how you could do this:

public static String removeDuplicates(String s) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (sb.indexOf(String.valueOf(c)) == -1) {
            sb.append(c);
        }
    }
    return sb.toString();
}

This function iterates over each character in the input string, s, and checks whether it has already been added to the StringBuilder object sb. If it has not been added, it is appended to sb. At the end, the StringBuilder object is converted to a String and returned.

Here's an example of how you could use this function:

String s = "hello world";
String s2 = removeDuplicates(s);  // s2 is "helo wrd"

Note that this function only works for removing duplicates of individual characters. If you want to remove duplicates of substrings, you will need to use a different approach.