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单选题
class Dog { }  class Harrier extends Dog { }  class DogTest {  public static void main(String [] args) {  Dog d1 = new Dog();  Harrier h1 = new Harrier();  Dog d2 = h1;  Harrier h2 = (Harrier) d2;  Harrier h3 = d2;  }  }  下面哪一项是正确的?()
A

编译失败

B

2个Dog对象被创建

C

2个Harrier对象被创建

D

3个Harrier对象被创建


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更多 “单选题class Dog { }  class Harrier extends Dog { }  class DogTest {  public static void main(String [] args) {  Dog d1 = new Dog();  Harrier h1 = new Harrier();  Dog d2 = h1;  Harrier h2 = (Harrier) d2;  Harrier h3 = d2;  }  }  下面哪一项是正确的?()A 编译失败B 2个Dog对象被创建C 2个Harrier对象被创建D 3个Harrier对象被创建” 相关考题
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考题 10. interface Jumper { public void jump(); }  ......  20. class Animal {}  ......  30. class Dog extends Animal { 31. Tail tail; 32. }  ......  40. class Beagle extends Dog implements Jumper {  41. public void jump() { }  42. }  .......  50. class Cat implements Jumper {  51. public void jump() { }  52. }  Which three are true?()A、 Cat is-a AnimalB、 Cat is-a JumperC、 Dog is-a AnimalD、 Dog is-a JumperE、 Cat has-a AnimalF、 Beagle has-a TailG、 Beagle has-a Jumper

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考题 class Dog { }  class Harrier extends Dog { }  class DogTest {  public static void main(String [] args) {  Dog d1 = new Dog();  Harrier h1 = new Harrier();  Dog d2 = h1;  Harrier h2 = (Harrier) d2;  Harrier h3 = d2;  }  }  下面哪一项是正确的?() A、编译失败B、2个Dog对象被创建C、2个Harrier对象被创建D、3个Harrier对象被创建

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考题 public class Pet{   private String name;   public Pet(){   System.out.print(1);  }   public Pet(String name){   System.out.print(2);  }   }   public class Dog extends Pet{  public Dog(String name){   //这里隐藏了一句代码:super.pet();   System.out.print(3);  }   }   执行new Dog(“棕熊”);后程序输出是哪项?() A、 23B、 1 3C、 123D、 321

考题 11. class Animal { public String noise() { return “peep”; } }  12. class Dog extends Animal {  13. public String noise() { return “bark”; }  14. }  15. class Cat extends Animal {  16. public String noise() { return “meow”; }  17. }  .....  30. Animal animal = new Dog();  31. Cat cat = (Cat)animal;  32. System.out.printIn(cat.noise());  What is the result?() A、 peepB、 barkC、 meowD、 Compilation fails.E、 An exception is thrown at runtime.

考题 Which Man class properly represents the relationship "Man has a best friend who is a Dog"?()A、class Man extends Dog{}B、class Man implements Dog{}C、class Man{private BestFriend dog;}D、class Man{private Dog bestFriend;}E、class Man{private Dog;}F、class Man{private BestFriend;}

考题 public class Pet{   private String name;   public Pet(){   System.out.print(1);  }   public Pet(String name){   System.out.print(2);   }  }   public class Dog extends Pet{  public Dog(){   System.out.print(4);  }   public Dog(String name){   //这里隐藏了一句代码:super.pet();   this();   System.out.print(3);  }  }   执行new Dog(“棕熊”);后程序输出是哪项?() A、 143B、 423C、 243D、 1134

考题 What produces a compiler error?()  A、 class A { public A(int x) {} }B、 class A {} class B extends A { B() {} }C、 class A { A() {} } class B { public B() {} }D、 class Z { public Z(int) {} } class A extends Z {}

考题 public class Pet{     private String name;     public Pet(){  System.out.print(1);    }  public Pet(String name){        System.out.print(2);    } }  public class Dog extends Pet{     public Dog(){  System.out.print(4);    }  public Dog(String name){        this();  System.out.print(3);    } }  执行new Dog(“棕熊”);后程序输出是哪项?()  A、 143B、 423C、 243D、 1134

考题 Which Man clsss properly represents the relationship "Man has a best friend who is a Dog"?()A、class Man extends Dog { }B、class Man implements Dog { }C、class Man { private BestFriend dog; }D、class Man { private Dog bestFriend; }E、class Man { private Dog; }F、class Man { private BestFriend; }

考题 Which Man class properly represents the relationship "Man has a best friend who is a Dog"?()A、class Man extends Dog { }B、class Man implements Dog { }C、class Man { private BestFriend dog; }D、class Man { private Dog bestFriend; }E、class Man { private DogbestFriend; }F、class Man { private BestFrienddog; }

考题 单选题public class Pet{   private String name;   public Pet(){   System.out.print(1);  }   public Pet(String name){   System.out.print(2);  }  }   public class Dog extends Pet{  public Dog(){   System.out.print(4);  }   public Dog(String name){   super(name);   System.out.print(3);  }   }   执行new Dog(“棕熊”);后程序输出是哪项?()A  33B  13C  23D  123

考题 多选题Given: 10. interface Jumper { public void jump(); } ...   20. class Animal {} ...   30. class Dog extends Animal {   31. Tail tail;   32. }   ...   40. class Beagle extends Dog implements Jumper{   41. public void jump() {}  42. }   ...   50. class Cat implements Jumper{   51. public void jump() {}   52. }. Which three are true?()ACat is-a JumperBCat is-a AnimalCDog is-a JumperDDog is-a AnimalEBeagle has-a JumperFCat has-a AnimalGBeagle has-a Tail

考题 单选题现有:  class Dog{ }  class Harrier extends Dog  { }       class DogTest{   public  static void main (String  []  args) {      Dog dl=new Dog();      Harrier hl=new Harrier();      Dog d2=hl;   Harrier h2=  (Harrier) d2;      Harrier h3=d2;     }      }  下面哪一项是正确的?()A 2个Dog对象被创建B 2个Harrier对象被创建C 3个Harrier对象被创建D 编译失败

考题 单选题11. class Animal { public String noise() { return “peep”; } }  12. class Dog extends Animal {  13. public String noise() { return “bark”; }  14. }  15. class Cat extends Animal {  16. public String noise() { return “meow”; }  17. }  .....  30. Animal animal = new Dog();  31. Cat cat = (Cat)animal;  32. System.out.printIn(cat.noise());  What is the result?()A  peepB  barkC  meowD  Compilation fails.E  An exception is thrown at runtime.

考题 单选题public class Pet{     private String name;     public Pet(){  System.out.print(1);    }  public Pet(String name){        System.out.print(2);    } }  public class Dog extends Pet{     public Dog(String name){        System.out.print(3);    } }  执行new Dog(“棕熊”);后程序输出是哪项?()A  23B  13C  123D  321

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Which Man class properly represents the relationship “Man has a best friend who is a Dog”?()A  class Man extends Dog { }B  class Man implements Dog { }C  class Man { private BestFriend dog; }D  class Man { private Dog bestFriend; }E  class Man { private Dog }F  class Man { private BestFriend }

考题 单选题Which Man class properly represents the relationship "Man has a best friend who is a Dog"?()A class Man extends Dog { }B class Man implements Dog { }C class Man { private BestFriend dog; }D class Man { private Dog bestFriend; }E class Man { private DogbestFriend; }F class Man { private BestFrienddog; }

考题 单选题public class Pet{   private String name;   public Pet(){   System.out.print(1);  }   public Pet(String name){   System.out.print(2);  }   }   public class Dog extends Pet{  public Dog(String name){   //这里隐藏了一句代码:super.pet();   System.out.print(3);  }   }   执行new Dog(“棕熊”);后程序输出是哪项?()A  23B  1 3C  123D  321

考题 单选题public class Pet{     private String name;     public Pet(String name){       this.name = name;    }  public void speak(){     System.out.print(name); }  }  public class Dog extends Pet{     public Dog(String name){       super(name);    }  public void speak(){    super.speak();  System.out.print(“ Dog ”);    } }  执行代码   Pet pet = new Dog(“京巴”);  pet.speak();  后输出的内容是哪项?()A  京巴B  京巴 DogC  nullD  Dog京巴

考题 单选题Which Man class properly represents the relationship "Man has a best friend who is a Dog"?()A class Man extends Dog{}B class Man implements Dog{}C class Man{private BestFriend dog;}D class Man{private Dog bestFriend;}E class Man{private Dog;}F class Man{private BestFriend;}

考题 多选题10. interface Jumper { public void jump(); }  ......  20. class Animal {}  ......  30. class Dog extends Animal { 31. Tail tail; 32. }  ......  40. class Beagle extends Dog implements Jumper {  41. public void jump() { }  42. }  .......  50. class Cat implements Jumper {  51. public void jump() { }  52. }  Which three are true?()ACat is-a AnimalBCat is-a JumperCDog is-a AnimalDDog is-a JumperECat has-a AnimalFBeagle has-a TailGBeagle has-a Jumper

考题 单选题1. class Animal { Animal getOne() { return new Animal(); } }  2. class Dog extends Animal {  3. // insert code here   4. }  5.  6. class AnimalTest {  7. public static void main(String [] args) {  8. Animal [] animal = { new Animal(), new Dog() } ;  9. for( Animal a : animal) {  10. Animal x = a.getOne();  11. }  12. }  13. }  和代码:  3a. Dog getOne() {  return new Dog();  }  3b. Animal getOne() {  return new Dog();  }  第 3 行中插入的哪项将编译且运行无异常?()A 3a行B 3b行C 3a行或3b行D 既非3a,也非3b

考题 单选题class Animal{ Animal getOne(){return new Animal();}}   class Dog extends Animal{   //insert code here   }   class AnimalTest{   public static void main(String[] args){   Animal[] animal={ new Animal(), new Dog()};   for(Animal a:animal){   Animal x= a.getOne();   }   }   }   和代码:   3a.Dog getOne() { return new Dog();}   3b.Animal getOne() { return new Dog();}   第3行中插入的哪项编译且运行无异常?A 3a行或3b行B 既非3a,也非3bC 3a行D 3b行