Java remove duplicate char in String

/**
 * @author lautturi.com 
 * Java example: remove duplicate char from string in java
 */

import java.util.*;

public class Lautturi {

	public static String removeDup(String str) {
		String result = "";
		for (int i = 0; i < str.length(); i++)
			if (!result.contains("" + str.charAt(i)))
				result += "" + str.charAt(i);
		return result;
	}

	public static void main(String args[]) {

		String str = "AAAABBBCCBDEEFDDFF";
		String newStr = removeDup(str);
		System.out.println(newStr);

	}
}

output:

ABCDEF