10. interface Foo {}  11. class Alpha implements Foo {}  12.

题目
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;

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相似问题和答案

第1题:

10. class Foo {  11. static void alpha() { /* more code here */ }  12. void beta() { /* more code here */ }  13. }  Which two are true?()

  • A、 Foo.beta() is a valid invocation of beta().
  • B、 Foo.alpha() is a valid invocation of alpha().
  • C、 Method beta() can directly call method alpha().
  • D、 Method alpha() can directly call method beta().

正确答案:B,C

第2题:

class One {   public One foo() { return this; }  }  class Two extends One {  public One foo() { return this; }  }  class Three extends Two {   // insert method here  }  Which two methods, inserted individually, correctly complete the Three class?()

  • A、 public void foo() { }
  • B、 public int foo() { return 3; }
  • C、 public Two foo() { return this; }
  • D、 public One foo() { return this; }
  • E、 public Object foo() { return this; }

正确答案:C,D

第3题:

ClicktheExhibitbutton.Given:11.<%com.example.Advisoradvisor=newcom.example.Advisor();%>12.<%request.setAttribute("foo",advisor);%>Assumingtherearenoother"foo"attributesinthewebapplication,whichthreearevalidELexpressionsforretrievingtheadvicepropertyofadvisor?()

A.${foo.advice}

B.${request.foo.advice}

C.${requestScope.foo.advice}

D.${requestScope[foo[advice]]}

E.${requestScope["foo"]["advice"]}


参考答案:A, C, E

第4题:

1.public class Test {  2.public static void main (String args[]) {  3.class Foo {  4.public int i = 3;  5.}  6.Object o = (Object) new Foo();  7.Foo foo = (Foo)o;  8.System.out.printIn(foo. i); 9. }  10.}   What is the result?()  

  • A、 Compilation will fail.
  • B、 Compilation will succeed and the program will print “3”
  • C、 Compilation will succeed but the program will throw a ClassCastException at line 6.
  • D、 Compilation will succeed but the program will throw a ClassCastException at line 7.

正确答案:B

第5题:

public class Test {  public static void main(String args[]) {  class Foo {  public int i = 3; }  Object o = (Object)new Foo();   Foo foo = (Foo)o;  System.out.println(“i = “ + foo.i); }  }  What is the result?()  

  • A、 i = 3
  • B、 Compilation fails.
  • C、 A ClassCastException is thrown at line 6.
  • D、 A ClassCastException is thrown at line 7.

正确答案:A

第6题:

class One {  void foo() {}  }  class Two extends One {   //insert method here  }  Which three methods, inserted individually at line 14, will correctly complete class Two?()

  • A、 int foo() { /* more code here */ }
  • B、 void foo() { /* more code here */ }
  • C、 public void foo() { /* more code here */ }
  • D、 private void foo() { /* more code here */ }
  • E、 protected void foo() { /* more code here */ }

正确答案:B,C,E

第7题:

Which statements concerning the relationships between the following classes are true?()   class Foo {  int num;   Baz comp = new Baz();   }   class Bar {  boolean flag;   }   class Baz extends Foo {   Bar thing = new Bar();   double limit;   }  

  • A、A Bar is a Baz.
  • B、A Foo has a Bar.
  • C、A Baz is a Foo.
  • D、A Foo is a Baz.
  • E、A Baz has a Bar.

正确答案:C,E

第8题:

Given: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;


参考答案:B

第9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;

正确答案:B

第10题:

interface foo {   int k = 0;   }    public class test implements Foo (   public static void main(String args) (    int i;   Test test = new test ();   i= test.k;   i= Test.k;   i= Foo.k;   )   )   What is the result? ()

  • A、 Compilation succeeds.
  • B、 An error at line 2 causes compilation to fail.
  • C、 An error at line 9 causes compilation to fail.
  • D、 An error at line 10 causes compilation to fail.
  • E、 An error at line 11 causes compilation to fail.

正确答案:A

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