android裏queryIntentActivities(resolveIntent, 0);返回的list的size為什麽是0？

Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);

resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);

PackageManager pm = context.getPackageManager();

List<ResolveInfo> apps = pm.queryIntentActivities(resolveIntent, 0);