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对下面的代码，哪段描述是错误的？（) public class Door{ } public class House{ public House（){ Door door = new Door（);}}
A．Door是一个类。
B．House是一个从Door继承的类。
C．House的构造函数中声明了一个名为door的变量。
D．door是一个对象。
参考答案和解析
B
更多 “对下面的代码，哪段描述是错误的？（) public class Door{ } public class House{ public House（){ Door door = new Door（);}}A．Door是一个类。B．House是一个从Door继承的类。C．House的构造函数中声明了一个名为door的变量。D．door是一个对象。” 相关考题
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阅读以下说明和C++代码。【说明】传输门是传输系统中的重要装置。传输门具有Open(打开)、Closed(关闭)、Opening (正在打开)、StayOpen(保持打开)和Closing(正在关闭)五种状态。触发传输门状态转换的事件有click、complete和timeout三种。事件与其相应的状态转换如下图所示。下面的C++代码1与C++代码2分别用两种不同的设计思路对传输门进行状态模拟，请填补代码中的空缺。【C++代码1】const int CLOSED=1； const int PENING=2；const int PEN=3； const int CLOSING=4；const int STAYOPEN=5； //定义状态变量，用不同整数表示不同状态class Door {Private：int state； //传输门当前状态void setState(int state){ this-＞state=state；} //设置当前状态public：Door()：state(CLOSED){}；void getState(){ //根据当前状态输出相应的字符串switch(state){case OPENING： cout＜＜"OPENING"＜＜endl； break；case CLOSED： cout＜＜"CLOSED"＜＜endl； break；case OPEN： cout＜＜"OPEN"＜＜endl； break；case CLOSING： cout＜＜"CLOSING"＜＜endl； break；case STAYOPEN：cout＜＜"STAYOPEN"＜＜endl； break；}};void click() { //发生click事件时进行状态转换if ((1)) setState(OPENING)；else if ((2)) setState(CLOSING)；else if ((3)) setState(STAYOPEN)；}void timeout(){ //发生timeout事件时进行状态转换if (state == OPEN) setState(CLOSING)；}void complete(){ //发生complete事件时进行状态转换if (state == OPENING) setState(OPEN)；else if (state == CLOSING) setState(CLOSED)；}};int main(){Door aDoor；aDoor.getState()；aDoor.click()； aDoor.getState()；aDoor.complete()；aDoor.getState()； aDoor.click()；aDoor.getState()；aDoor.click()； aDoor.getState()； return 0；}【C++代码2】class Door {public：DoorState *CLOSED，*OPENING，*OPEN，*CLOSING，*STAYOPEN，*state；Door()；virtual～Door(){……//释放申请的内存，此处代码省略)；void setState(DoorState *state) { this-＞state = state；}void getState(){//此处代码省略，本方法输出状态字符串，//例如，当前状态为CLOSED时，输出字符串为“CLOSED”}；void click()；void timeout()；void complete()；}；Door::Door(){CLOSED = new DoorClosed(this)； OPENING = new DoorOpening(this)；PEN = new DoorOpen(this)； CLOSING = new DoorClosing(this)；STAYOPEN = new DoorStayOpen(this)；state = CLOSED；}void Door :: click() {(4)；)void Door :: timeout() {(5)；)void Door :: complete() {(6)；}class DoorState//定义一个抽象的状态，它是所有状态类的基类{protected：Door *door；public：DoorState(Door *door) {this-＞door = door；}virtual～DoorState(void)；virtual void click() {}virtual void complete(
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下面程序的结果是 ______。includeclass A{ public:virtual voidfun()=0{};};class
下面程序的结果是 ______。 #include＜iostream.h＞ class A{ public: virtual void fun()=0{}; }; class B:public A{ public: void fun () {cout＜＜ "new file" ;} }; class C: public A{ public: void fun (){cout＜＜"open file"＜＜ " " } }; class D: public A{ public: void fun () {cout＜＜ "save file\n" ;} }; void main() { A a,*p; B b; C c; D d; p=c; p-＞fun (); p=b; p-＞fun (); p=d; p-＞fun(); }A．new file open file save fileB．new file new file new fileC．编译出错D．open file new file save file
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Which two allow the class Thing to be instantiated using new Thing（）？A、 public class Thing { }B、 public class Thing { public Thing（） {} }C、 public class Thing { public Thing（void） {} }D、 public class Thing { public Thing（String s） {} }E、 public class Thing { public void Thing（） {} public Thing（String s） {} }
考题
下列代码正确的是哪项？（） A、 public class Session implements Runnable， Clonable{ public void run （）；public Object clone （） ； }B、 public class Session extends Runnable， Cloneable { public void run（） {/*dosomething*/} public Object clone（） {/*make a copy*/} }C、 public abstract class Session implements Runnable， Clonable { public void run（） {/*do something*/} public Object clone（） {/*make a copy*/} }D、 public class Session implements Runnable， implements Clonable { public void run（） {/*do something*/} public Object clone（） {/*make a copy*/} }
考题
package geometry； public class Hypotenuse { public InnerTriangle it = new InnerTriangle（）； class InnerTriangle { public int base； public int height； } } Which is true about the class of an object that can reference the variable base？ （）A、 It can be any class.B、 No class has access to base.C、 The class must belong to the geometry package.D、 The class must be a subclass of the class Hypotenuse.
考题
单选题下列代码正确的是哪项？（）A
public class Session implements Runnable， Clonable{ public void run （）；public Object clone （） ； }B
public class Session extends Runnable， Cloneable { public void run（） {/*dosomething*/} public Object clone（） {/*make a copy*/} }C
public abstract class Session implements Runnable， Clonable { public void run（） {/*do something*/} public Object clone（） {/*make a copy*/} }D
public class Session implements Runnable， implements Clonable { public void run（） {/*do something*/} public Object clone（） {/*make a copy*/} }
考题
单选题public class Pet{ public void speak（）{ System.out.print（“ Pet ”）； } } public class Cat extends Pet{ public void speak（）{ System.out.print（“ Cat ”）； } } public class Dog extends Pet{ public void speak（）{ System.out.print（“ Dog ”）； } } 执行代码 Pet[] p = {new Cat（），new Dog（），new Pet（）}； for（int i=0；i〈p.length；i++） p[i].speak（）； 后输出的内容是哪项？（）A
Pet Pet PetB
Cat Cat CatC
Cat Dog PetD
Cat Dog Dog
考题
单选题package geometry； public class Hypotenuse { public InnerTriangle it = new InnerTriangle（）； class InnerTriangle { public int base； public int height； } } Which is true about the class of an object that can reference the variable base？ （）A
It can be any class.B
No class has access to base.C
The class must belong to the geometry package.D
The class must be a subclass of the class Hypotenuse.
考题
多选题Which two allow the class Thing to be instantiated using new Thing（）？Apublic class Thing { }Bpublic class Thing { public Thing（） {} }Cpublic class Thing { public Thing（void） {} }Dpublic class Thing { public Thing（String s） {} }Epublic class Thing { public void Thing（） {} public Thing（String s） {} }
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问答题Can you find the missing value on the roof of the following house? Each of the numbers on the windows and door must be used only once and no number can be reversed.
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单选题What should you do if you are making changes to your house?A
Check 700 plans to build new buildings.B
Think carefully about those living near you.C
Give enough details to the people next door.
考题
单选题下列程序的运行结果是（ ）。class Shape{ public Shape(){ System.out.print("Shape"); }}class Circle extends Shape{ public Circle(){ System.out.print("Circle"); }}public class Test{ public static void main(String[]args){ Shape d=new Circle(); }}A
ShapeB
CircleC
ShapeCircleD
程序有错误
考题
单选题He _____ the door with his fist, but got no answer from the house.A
refrainedB
registeredC
refundedD
pounded
考题
单选题When a fire happens, _____ if you open the hot door.A
the fire will grow more quicklyB
the electricity will be cut offC
the door will soon be on fireD
the house will fall down
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