我想计算使用该设备的所有缓存内存的总和。为此，我收到一个编译时间错误:IPackageStatsObservercannotberesolvedtoatype我在代码中提到过这个错误2次:publiclongtotalCacheSize(){totalSize=0;PackageManagerpackageManager=getApplicationContext().getPackageManager();/*Listpacks=packageManager.getInstalledPackages(PackageManager.GET_ACTIVITIES);*///Package