publicclassPlant{privateStringname;publicPlant(Stringname){this.name=name;}publicStringgetName(){returnname;}}publicclassTreeextendsPlant{publicvoidgrowFruit(){}publicvoiddropLeaves(){}}Whichistrue?() A.Thecodewillcompilewithoutchanges.B.ThecodewillcompileifpublicTree（）{Plant（）；}isaddedtotheTreeclass.C.ThecodewillcompileifpublicPlant（）{Tree（）；}isaddedtothePlantclass.D.ThecodewillcompileifpublicPlant（）{this（”fern”）；}isaddedtothePlantclass.E.ThecodewillcompileifpublicPlant（）{Plant（”fern”）；}isaddedtothePlantclass.
publicclassPlant{privateStringname;publicPlant(Stringname){this.name=name;}publicStringgetName(){returnname;}}publicclassTreeextendsPlant{publicvoidgrowFruit(){}publicvoiddropLeaves(){}}Whichistrue?()
A.Thecodewillcompilewithoutchanges.
B.ThecodewillcompileifpublicTree（）{Plant（）；}isaddedtotheTreeclass.
C.ThecodewillcompileifpublicPlant（）{Tree（）；}isaddedtothePlantclass.
D.ThecodewillcompileifpublicPlant（）{this（”fern”）；}isaddedtothePlantclass.
E.ThecodewillcompileifpublicPlant（）{Plant（”fern”）；}isaddedtothePlantclass.
相关考题：
publicclassEmployee{privateStringname；publicEmployee（Stringname）{this.name=name；}publicStringgetName（）{returnname；}}publicclassManagerextendsEmployee{privateStringdepartment；publicManager（Stringname，Stringdepartment）{this.department=department；super（name）；（应于上一行掉位置）System.out.println（getName（））；}}Super的位置是否在方法的首行执行语句newManager（smith”，”SALES”）后程序的输出是哪项？（）A.smithB.nullC.SALESD.编译错误
publicclassPerson{2.privateStringname;3.publicPerson(Stringname){this.name=name;}4.publicbooleanequals(Personp){5.returnp.name.equals(this.name);6.}7.}Whichistrue?() A.TheequalsmethoddoesNOTproperlyoverridetheObject.equalsmethod.B.Compilationfailsbecausetheprivateattributep.namecannotbeaccessedinline5.C.Toworkcorrectlywithhash-baseddatastructures，thisclassmustalsoimplementthehashCodemethod.D.WhenaddingPersonobjectstoajava.util.Setcollection，theequalsmethodinline4willpreventduplicates.
publicclassPerson{privatename;publicPerson(Stringname){this.name=name;}publicbooleanequals(Objecto){if(!oinstanceofPerson)returnfalse;Personp=(Person)o;returnp.name.equals(this.name);}}Whichistrue?() A.CompilationfailsbecausethehashCodemethodisnotoverridden.B.AHashSetcouldcontainmultiplePersonobjectswiththesamename.C.AllPersonobjectswillhavethesamehashcodebecausethehashCodemethodisnotoverridden.D.IfaHashSetcontainsmorethanonePersonobjectwithname=”Fred”，thenremovinganother person，alsowithname=”Fred”，willremovethemall.
publicclassNamedCounter{privatefinalStringname；privateintcount；publicNamedCounter（Stringname）{this.name=name；}publicStringgetName（）{returnname；}publicvoidincrement（）{coount++；}publicintgetCount（）{returncount；}publicvoidreset（）{count=0；}}Whichthreechangesshouldbemadetoadaptthisclasstobeusedsafelybymultiplethreads？（）A.declarereset（）usingthesynchronizedkeywordB.declaregetName（）usingthesynchronizedkeywordC.declaregetCount（）usingthesynchronizedkeywordD.declaretheconstructorusingthesynchronizedkeywordE.declareincrement（）usingthesynchronizedkeyword
publicclassPerson{privatename;publicPerson(Stringname){this.name=name;}publicinthashCode(){return420;}}Whichistrue?() A.ThetimetofindthevaluefromHashMapwithaPersonkeydependsonthesizeofthemap.B.DeletingaPersonkeyfromaHashMapwilldeleteallmapentriesforallkeysoftypePerson.C.InsertingasecondPersonobjectintoaHashSetwillcausethefirstPersonobjecttoberemovedasaduplicate.D.ThetimetodeterminewhetheraPersonobjectiscontainedinaHashSetisconstantanddoesNOTdependonthesizeofthemap.
interface Playable {void play();}interface Bounceable {void play();}interface Rollable extends Playable, Bounceable {Ball ball = new Ball("PingPang");}class Ball implements Rollable {private String name;public String getName() {return name;}public Ball(String name) {this.name = name;}public void play() {ball = new Ball("Football");System.out.println(ball.getName());}}这个错误不容易发现。
分析如下代码，其中this关键字的意思是 public class Demo{ private String name; public String getName（){ return name; } public void setName（String name){ this.name = name; } }A．name属性B．Demo类种内部指代当前对象的引用C．Demo类引用所在的方法D．Demo类中对重载构造方法的引用
分析如下代码，其中this关键字的意思是 public class Demo{ private String name; public String getName（){ return name; } public void setName（String name){ this.name = name; } }A．name属性B．Demo类中内部指代当前对象的引用C．Demo类引用所在的方法D．Demo类中对重载构造方法的引用
如下所示的Java代码，其中this关键字的意思是 public class Test { private String name; public String getName（) { return name; } public void setName（String name) { this.name = name; //this关键字所在的行 } }A．name属性B．Test类的内部指代自身的引用C．Test类的对象引用Test类的其他对象D．指所在的方法