字符串的排列(全排列问题)

public class Permutation {
    public ArrayList<String> Permutation(String str) {
        ArrayList<String> list=new ArrayList<>();
        getAll(str.toCharArray(),0,list);
        Collections.sort(list,new myComp());
        return list;
    }

    public void getAll(char[] chars,int index,ArrayList<String> list) {
        if (index==chars.length-1){
            if (!list.contains(new String(chars))){
                list.add(new String(chars));
            }
            return;
        }else {
            for(int i=index;i<chars.length;i++){
                swap(chars,index,i);
                getAll(chars,index+1,list);
                swap(chars,index,i);
            }
        }
    }
    public void swap(char[] chars,int indexa,int indexb){
        char temp=chars[indexa];
        chars[indexa]=chars[indexb];
        chars[indexb]=temp;
    }

    class  myComp implements Comparator<String>{
        @Override
        public int compare(String o1, String o2) {
            return (o1+o2).compareTo(o2+o1);
        }
    }
}