can't setbackground many times~

[caoyanglee]

btn_pay.getDelegate().setBackgroundColor(R.color.gray);---------first time【it works】

but~

btn_pay.getDelegate().setBackgroundColor(R.color.colorPrimary);----second time【it can't work!】

[tysheng]

btn_pay.getDelegate().setBackgroundColor(ContextCompat.getColor(context,R.color.colorPrimary));