as去掉字符串中的重复字符

package  antCodes
{
    /**
     * ...
     * 去掉字符串中的重复字符
     * 
     * @author Dong
     */
    public class ToRepeat 
    {
        public var str:String = "";
        public function ToRepeat() 
        {
            
        }
        
        //去掉字符串中的重复字符
        public function toRepeat(str:String):String {
            var len:int = str.length;
            var i:int = 1;
            while (i < len) {
                if (this.str.match(str.charAt(i)) == null) {
                    this.str = this.str + str.charAt(i);
                    i++;
                }else {
                    i++;
                }
            }
            return this.str;
        }
    }

}