Whichdeterminesif“prefs”isadirectoryandexistsonthefilesystem?()A.Booleanexists=Directory.exists（“prefs”）；B.Booleanexists=（newFile（“prefs”））.isDir（）；C.Booleanexists=（newDirectory（“prefs”））.exists（）；D.Booleanexists=（newFile（“prefs”））.isDirectory（）；E.Boolean

题目
Whichdeterminesif“prefs”isadirectoryandexistsonthefilesystem?()

A.Booleanexists=Directory.exists（“prefs”）；

B.Booleanexists=（newFile（“prefs”））.isDir（）；

C.Booleanexists=（newDirectory（“prefs”））.exists（）；

D.Booleanexists=（newFile（“prefs”））.isDirectory（）；

E.Booleanexists=true；Try{Directoryd=newDirectory（“prefs”）；} catch（FileNotFoundExceptione）{exists=false；}

相似考题

1.SharedPreferences保存文件的路径和扩展名是()。A./data/data/shared_prefs/*.txtB./data/data/package name/shared_prefs/*.xmlC./mnt/sdcard/指定文件夹指定扩展名D.任意路径指定扩展名

2.Examine this command:SQL > exec DBMS_STATS.SET_TABLE_PREFS (‘SH’, ‘CUSTOMERS’, ‘PUBLISH’, ‘false’);Which three statements are true about the effect of this command?()A. Statistics collection is not done for the CUSTOMERS table when schema stats are gathered.B. Statistics collection is not done for the CUSTOMERS table when database stats are gathered.C. Any existing statistics for the CUSTOMERS table are still available to the optimizer at parse time.D. Statistics gathered on the CUSTOMERS table when schema stats are gathered are stored as pending statistics.E. Statistics gathered on the CUSTOMERS table when database stats are gathered are stored as pending statistics.

3.Examinethecommand:SQL>DBMS_STATS.SET_TABLE_PREFS(’SH’,’CUSTOMERS’,’PUBLISH’,’false’);Whichstatementdescribestheeffectoftheabovecommand()A.AutomaticstatisticscollectionisstoppedfortheCUSTOMERStable.B.StatisticsfortheCUSTOMERStablearelockedandcannotbeoverwritten.C.ExistingstatisticsfortheCUSTOMERStablebecomeunusableforthequeryoptimizer.D.Subsequently，statisticsgatheredontheCUSTOMERStablearestoredaspendingstatistics

4.Youexecutedthefollowingcommands：SQL>ALTERSESSIONSETOPTIMIZER_USE_PENDING_STATISTICS=false；SQL>EXECUTEDBMS_STATS.SET_TABLE_PREFS（’SH’，’CUSTOMERS’，’PUBLISH’，’false’）；SQL>EXECUTEDBMS_STATS.GATHER_TABLE_STATS（’SH’，’CUSTOMERS’）；WhichstatementiscorrectregardingtheabovestatisticscollectionontheSH.CUSTOMERStableintheabovesession？（）A.Thestatisticsarestoredinthependingstatisticstableinthedatadictionary.B.Thestatisticsaretreatedasthecurrentstatisticsbytheoptimizerforallsessions.C.Thestatisticsaretreatedasthecurrentstatisticsbytheoptimizerforthecurrentsessionsonly.D.Thestatisticsaretemporaryandusedbytheoptimizerforallsessionsuntilthissessionterminates.

相关内容