AlertDialog 按鈕顏色

AlertDialog alertDialog=new AlertDialog.Builder(mActivity)
        .setTitle("上傳作業")
        .setMessage("確定要上傳?")
        .setPositiveButton("確定",
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        showUploadSuccessDialog();
                    }
                })
        .setNegativeButton("取消",null)
        .show();

alertDialog.getButton(dialog.BUTTON_NEGATIVE).setTextColor(Color.parseColor("#000000"));