从EditText中删除特定文本

Question

如果用户尝试从中删除某些字符，我想删除以@开头的特定文本 我试试这段代码

mBinding.questionEdtHelp.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                mPreviousLength = charSequence.length();
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
              if (i1 - i2 == 1) {
                    if ( charSequence.toString().charAt(i) == '@') {
                        mBinding.questionEdtHelp.getText().delete(i , i1);
                    }
                }

            }

任何人都可以帮助我吗？