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现有:      1  Interface F{}  2  class A implements F{}      3  class B extends A{}      4  class C extends B{  5    public static void main(String[]  args){      6    B b=new B();  7    //inSert C0de here      8    }      9    } 下列哪行代码插入到第7行,将抛出java.lang.ClassCaseException异常()

  • A、   A a=b;
  • B、  F f=  (C)b;
  • C、  F f=  (A)b;
  • D、  B bb=  (B)(A)b;

参考答案

更多 “ 现有:      1  Interface F{}  2  class A implements F{}      3  class B extends A{}      4  class C extends B{  5    public static void main(String[]  args){      6    B b=new B();  7    //inSert C0de here      8    }      9    } 下列哪行代码插入到第7行,将抛出java.lang.ClassCaseException异常()A、   A a=b;B、  F f=  (C)b;C、  F f=  (A)b;D、  B bb=  (B)(A)b;” 相关考题
考题 interface A{int x = 0;}class B{int x =1;}class C extends B implements A {public void pX(){System.out.println(x);}public static void main(String[] args) {new C().pX();}}

考题 设有如下代码:interface IFace{}class CFace implements IFace{}class Base{}public class ObRef extends Base{public static void main(String argv[]){ObRef bj = new ObRef();Base b = new Base();Object obj1 = new Object();IFace obj2 = new CFace();//Here}}则在 //Here处插入哪个代码将不出现编译和运行错误。A.obj1=obj2;B.b=obj;C.obj=b;D.obj1=b;

考题 1. interface Animal {   2. void eat();   3. }   4.   5. // insert code here   6.   7. public class HouseCat implements Feline {   8. public void eat() { }   9. }   和以下三个接口声明:   interface Feline extends Animal { }   interface Feline extends Animal { void eat(); }   interface Feline extends Animal { void eat() { } }   分别插入到第 5 行,有多少行可以编译?()A、0B、1C、2D、3

考题 现有:  1.  interface Animal  f      2.    void eat();      3.    }      4.  5.  // insert code here      6.  7. public class HouseCat implements Feline  {      8.    public void eat()    {  }     9.  }  和以下三个接口声明:  interface Feline extends Animal  (  )  interface Feline extends Animal  {void eat();    }  interface Feline extends Animal  {void eat()    {  }  }   分别插入到第5行,有多少行可以编译?   A、  0B、  1C、  2D、  3

考题 现有:   1.  class HorseRadish {   2.    // insert code here   3.    protected HorseRadish(int x) {    4.      System.out.println("bok choy");  5.    }  6.  }   7.  class Wasabi extends HorseRadish {   8.    public static void main(String [] args) {   9.      Wasabi w = new Wasabi();  10.   }    11. }   分别插入到第 2 行,哪两项允许代码编译并产生"bok choy" 输出结果?() A、 // just a commentB、 protected HorseRadish() { }C、 protected HorseRadish() { this(42);}D、 protected  HorseRadish() { new HorseRadish (42);}

考题 1. class HorseRadish {   2. // insert code here   3. protected HorseRadish(int x) {  4. System.out.println("bok choy");   5. }   6. }   7. class Wasabi extends HorseRadish {   8. public static void main(String [] args) {   9. Wasabi w = new Wasabi();  10. }   11. }   分别插入到第 2 行,哪两项允许代码编译并产生"bok choy" 输出结果?()  A、 // just a commentB、 protected HorseRadish() { }C、 protected HorseRadish() { this(42);}D、 protected HorseRadish() { new HorseRadish (42);}

考题 Which statements, when inserted at the indicated position in the following code, will cause a runtime exception when attempting to run the program?()   class A {}   class B extends A {}   class C extends A {}   public class Q3ae4 {   public static void main(String args[]) {   A x = new A();   B y = new B();   C z = new C();   // insert statement here   }   } A、x = y;B、z = x;C、y = (B) x;D、z = (C) y;E、y = (A) y;

考题 对于下列代码: 1) class Person {   2} public void printValue(int i, int j) {//... }     3} public void printValue(int i){//... }    4} }   5) public class Teacher extends Person { 6} public void printValue( ) {//... }     7} public void printValue(int i) {//...}     8} public static void main(String args[]){     9} Person t = new Teacher( );     10} t.printValue(10);     11} } 第10行语句将调用哪行语句?()A、 line 2B、 line 3C、 line 6D、 line 7

考题 现有:   1. class Book {   2. private final void read() { System.out.print("book "); }   3. }   4. class Page extends Book {   5. public static void main(String [] args) {   6. // insert code here   7. }   8. private final void read() { System.out.print("page "); }   9. }   和如下三个代码片段( x, y, z ):   x. // just a comment   y. new Page().read();  z. new Book().read();   分别插入到第6行,有几个允许代码通过编译并可以运行且无异常?() A、 0B、 1C、 2D、 3

考题 1. class Alpha { void m1() {} }   2. class Beta extends Alpha { void m2() { } }   3. class Gamma extends Beta { }   4.   5. class GreekTest {   6. public static void main(String [] args) {   7. a Alpha [] a = {new Alpha(), new Beta(), new Gamma() };   8. for(Alpha a2 : a) {   9. a2.m1();   10. if (a2 instanceof Beta || a2 instanceof Gamma)   11. //insert code here   12. }   13. }   14. }   哪一行代码插入到第11行,将编译但是会在运行时产生异常?()  A、 a2.m2();B、 ((Beta)a2).m2();C、 ((Alpha)a2).m2();D、 ((Gamma)a2).m2();

考题 现有:   1.  class Alpha { void m1() {} }   2.  class Beta extends Alpha { void m2() { } }   3.  class Gamma extends Beta { }   4.   5.  class GreekTest {   6.    public static void main(String [] args) {   7.      Alpha [] a = {new Alpha(), new Beta(), new Gamma() };   8.      for(Alpha a2 : a) {   9.        a2.m1();    10.       if (a2 instanceof Beta || a2 instanceof Gamma)    11.         //insert code here   12.     }    13.   }   14. }    哪一行代码插入到第11行,将编译但是会在运行时产生异常?() A、 a2.m2();B、 ((Beta)a2).m2();C、 ((Alpha)a2).m2();D、 ((Gamma)a2).m2();

考题 现有:  interface Animal {       void eat () ;       }       //insert code here       public class HouseCat extends Feline {       public void eat() { }       }  和五个申明  abstract class Feline implements Animal { }  abstract  class  Feline  implements  Animal  {  void eat () ;  }  abstract class Feline implements Animal { public void eat();}  abstract class Feline implements Animal { public void eat() {}  }  abstract class Feline implements Animal { abstract public void eat();} 结果为:()      A、1B、2C、3D、4

考题 现有:  class HorseRadish  {      //insert code here  protected HorseRadish (int x)    {      System.out.println ("bok choy");      }      }  class Wasabi extends HorseRadish  {  public static void main (String  []  args){    Wasabi w- new Wasabi();     }     }  分别插入到第2行,哪两项允许代码编译并产生”bok choy”输出结果()A、 protected HorseRadish()  {this (42);}B、  protected HorseRadish()  {}C、  //just a commentD、  protected  HorseRadish()  {  new HorseRadish (42);}

考题 现有:  1. import java.util.*;      2.  3. Class FindStuff  {  4.public static void main (String[]args)    {      5,    //insert code here      6.    c.put ("X", 123);      7.    }      8.  } 分别插入到第5行,哪三行允许代码编译?()    A、 Map c= new SortedMap();B、 HashMap c= new HashMap();C、 HashMap c= new Hashtalole();D、 SortedMap c= new TreeMap();E、 ArrayList c= new ArrayList();F、  MaD c = new LinkedHashMap();

考题 10. interface Foo {}  11. class Alpha implements Foo {}  12. class Beta extends Alpha {}  13. class Delta extends Beta {  14. public static void main( String[] args) {  15. Beta x = new Beta();  16. // insert code here  17. }  18. }  Which code, inserted at line 16, will cause a java.lang.ClassCastException?() A、 Alpha a = x;B、 Foo f= (Delta)x;C、 Foo f= (Alpha)x;D、 Beta b = (Beta)(Alpha)x;

考题 现有:  1. interface Animal {  2. void eat();  3. }  4.  5. // insert code here  6.  7. public class HouseCat extends Feline {  8. public void eat() { }  9. }   和五个声明:  abstract class Feline implements Animal { }  abstract class Feline implements Animal { void eat(); }  abstract class Feline implements Animal { public void eat(); }  abstract class Feline implements Animal { public void eat() { } }  abstract class Feline implements Animal { abstract public void eat(); }  分别插入到第5行,有几个可以通过编译?() A、0B、1C、2D、3

考题 现有:   1. interface Animal {    2.   void eat();   3.  }    4.   5. // insert code here    6.   7. public class HouseCat implements Feline {    8.   public void eat() { }   9. }   和以下三个接口声明:   interface Feline extends Animal { }    interface Feline extends Animal { void eat(); }     interface Feline extends Animal { void eat() { } }    分别插入到第 5 行,有多少行可以编译?()  A、 0B、 1C、 2D、 3

考题 多选题现有:  class HorseRadish  {      //insert code here  protected HorseRadish (int x)    {      System.out.println ("bok choy");      }      }  class Wasabi extends HorseRadish  {  public static void main (String  []  args){    Wasabi w- new Wasabi();     }     }  分别插入到第2行,哪两项允许代码编译并产生”bok choy”输出结果()Aprotected HorseRadish()  {this (42);}Bprotected HorseRadish()  {}C//just a commentDprotected  HorseRadish()  {  new HorseRadish (42);}

考题 单选题10. interface Foo {}  11. class Alpha implements Foo {}  12. class Beta extends Alpha {}  13. class Delta extends Beta {  14. public static void main( String[] args) {  15. Beta x = new Beta();  16. // insert code here  17. }  18. }  Which code, inserted at line 16, will cause a java.lang.ClassCastException?()A  Alpha a = x;B  Foo f= (Delta)x;C  Foo f= (Alpha)x;D  Beta b = (Beta)(Alpha)x;

考题 多选题现有:   1.  class HorseRadish {   2.    // insert code here   3.    protected HorseRadish(int x) {    4.      System.out.println("bok choy");  5.    }  6.  }   7.  class Wasabi extends HorseRadish {   8.    public static void main(String [] args) {   9.      Wasabi w = new Wasabi();  10.   }    11. }   分别插入到第 2 行,哪两项允许代码编译并产生"bok choy" 输出结果?()A// just a commentBprotected HorseRadish() { }Cprotected HorseRadish() { this(42);}Dprotected  HorseRadish() { new HorseRadish (42);}

考题 多选题1. class HorseRadish {   2. // insert code here   3. protected HorseRadish(int x) {  4. System.out.println("bok choy");   5. }   6. }   7. class Wasabi extends HorseRadish {   8. public static void main(String [] args) {   9. Wasabi w = new Wasabi();  10. }   11. }   分别插入到第 2 行,哪两项允许代码编译并产生"bok choy" 输出结果?()A// just a commentBprotected HorseRadish() { }Cprotected HorseRadish() { this(42);}Dprotected HorseRadish() { new HorseRadish (42);}

考题 单选题1. import java.util.*;  2. class SubGen {  3. public static void main(String [] args) {  4. //insert code here  5. }  6. }  class Alpha { }  class Beta extends Alpha { }  class Gamma extends Beta { }  和四段代码片段:  s1. ArrayList〈? extends Alpha〉 list1 = new ArrayList〈Gamma〉();  s2. ArrayList〈Alpha〉 list2 = new ArrayList〈? extends Alpha〉();  s3. ArrayList〈? extends Alpha〉 list3 = new ArrayList〈? extends Beta〉();  s4. ArrayList〈? extends Beta〉 list4 = new ArrayList〈Gamma〉(); ArrayList〈? extends Alpha〉 list5 = list4;  哪些片段分别插入到第4行,可允许代码编译?()A 只有s1B 只有s3C 只有s1和s3D 只有s1和s4

考题 单选题对于下列代码: 1) class Person {   2} public void printValue(int i, int j) {//... }     3} public void printValue(int i){//... }    4} }   5) public class Teacher extends Person { 6} public void printValue( ) {//... }     7} public void printValue(int i) {//...}     8} public static void main(String args[]){     9} Person t = new Teacher( );     10} t.printValue(10);     11} } 第10行语句将调用哪行语句?()A  line 2B  line 3C  line 6D  line 7

考题 单选题现有:   1.  class Alpha { void m1() {} }   2.  class Beta extends Alpha { void m2() { } }   3.  class Gamma extends Beta { }   4.   5.  class GreekTest {   6.    public static void main(String [] args) {   7.      Alpha [] a = {new Alpha(), new Beta(), new Gamma() };   8.      for(Alpha a2 : a) {   9.        a2.m1();    10.       if (a2 instanceof Beta || a2 instanceof Gamma)    11.         //insert code here   12.     }    13.   }   14. }    哪一行代码插入到第11行,将编译但是会在运行时产生异常?()A  a2.m2();B  ((Beta)a2).m2();C  ((Alpha)a2).m2();D  ((Gamma)a2).m2();

考题 单选题现有:   1. interface Animal {    2.   void eat();   3.  }    4.   5. // insert code here    6.   7. public class HouseCat implements Feline {    8.   public void eat() { }   9. }   和以下三个接口声明:   interface Feline extends Animal { }    interface Feline extends Animal { void eat(); }     interface Feline extends Animal { void eat() { } }    分别插入到第 5 行,有多少行可以编译?()A  0B  1C  2D  3

考题 单选题现有:  1.  interface Animal  f      2.    void eat();      3.    }      4.  5.  // insert code here      6.  7. public class HouseCat implements Feline  {      8.    public void eat()    {  }     9.  }  和以下三个接口声明:  interface Feline extends Animal  (  )  interface Feline extends Animal  {void eat();    }  interface Feline extends Animal  {void eat()    {  }  }   分别插入到第5行,有多少行可以编译?A   0B   1C   2D   3

考题 单选题Which statements, when inserted at the indicated position in the following code, will cause a runtime exception when attempting to run the program?()   class A {}   class B extends A {}   class C extends A {}   public class Q3ae4 {   public static void main(String args[]) {   A x = new A();   B y = new B();   C z = new C();   // insert statement here   }   }A x = y;B z = x;C y = (B) x;D z = (C) y;E y = (A) y;