private void DemoTextInputLayout()
        {
            mTextInputLayout = (TextInputLayout)mParentView.FindViewById(Resource.Id.text_input_layout).JavaCast<TextInputLayout>();
            mEditText = mTextInputLayout.EditText;
            mTextInputLayout.SetHint("请输入4位学号");

            mEditText.AddTextChangedListener(this);
        }