PackageManager pm = context.getPackageManager();
List<ResolveInfo> apps =
pm.queryIntentActivities(viewDocIntent, PackageManager.MATCH_DEFAULT_ONLY);
if (apps.size() > 0)
context.startActivity(viewDocIntent);
else
throw new ... SOMETHING
如果结果列表为空，您认为应该抛出哪个异常？