解决方法
add:autoDismiss(false)
new MaterialDialog.Builder(mainActivity) .title(R.string.title) .autoDismiss(false) .content(R.string.content) .positiveText(R.string.positive) .negativeText(R.string.negative) .positiveColor(setColor()) .callback(new MaterialDialog.ButtonCallback() { @Override public void onPositive(MaterialDialog dialog) { } }) .negativeColor(setColor()) .typeface(titleAndActions,contentAndListItems) .build() .show();