Java 把字符串括号里的内容提取出来

public static void main(String args[]){
        String str="您好{options{abc}}评论了您的{options{def}}";
        ArrayList<String>  word=new ArrayList<String>();
        int m=0,n=0;
        int count=0;
        for(int i=0;i<str.length();i++){
            if(str.charAt(i)=='{'){
                if(count==0){
                    m=i;
                }
                count++;
            }
            if(str.charAt(i)=='}'){
                count--;
                if(count==0){
                    n=i;
                    word.add(str.substring(m,n+1));
                }
            }
                     }
        for(String a : word){
            System.out.println(a);
        }
    }