单选题Click the Exhibit button. Which statement is true about the classes and interfaces in the exhibit?（）A Compilation will succeed for all classes and interfaces.B Compilation of class C will fail because of an error in line 2.C Compilation of class C

第1题：

public class SomeException {  } Class a：  public class a {  public void doSomething（） { }  } Class b：  public class b extends a {  public void doSomething（） throws SomeException { }  }  Which is true about the two classes？（） 

• A、 Compilation of both classes will fail.
• B、 Compilation of both classes will succeed.
• C、 Compilation of class a will fail. Compilation of class b will succeed.
• D、 Compilation of class a will fail. Compilation of class a will succeed.

第2题：

1. public interface A {  2. public void doSomething（String thing）；  3. }  1. public class AImpl implements A {  2. public void doSomething（String msg） { }  3. }  1. public class B {  2. public A doit（） {  3. // more code here  4. }  5.  6. public String execute（） { 7. // more code here  8. }  9. }  1. public class C extends B {  2. public AImpl doit（） {  3. // more code here  4. }  5.  6. public Object execute（） {  7. // more code here  8. }  9. }  Which statement is true about the classes and interfaces in the exhibit？（） 

• A、 Compilation will succeed for all classes and interfaces.
• B、 Compilation of class C will fail because of an error in line 2.
• C、 Compilation of class C will fail because of an error in line 6.
• D、 Compilation of class AImpl will fail because of an error in line 2.

第3题：

第4题：

public class X {  public static void main （String[] args）  {  byte b = 127；  byte c = 126；  byte d = b + c；  }  }   Which statement is true？（）  

• A、 Compilation succeeds and d takes the value 253.
• B、 Line 5 contains an error that prevents compilation.
• C、 Line 5 throws an exception indicating “Out of range”
• D、 Line 3 and 4 contain error that prevent compilation.
• E、 The compilation succeeds and d takes the value of 1.

第5题：

1. class SuperClass {  2. public a geta（） {  3. return new a（）；  4. }  5. }  6. class SubClass extends SuperClass {  7. public b geta（） {  8. return new b（）；  9. }  10. }  Which is true？（） 

• A、 Compilation will succeed if a extends b.
• B、 Compilation will succeed if b extends a.
• C、 Compilation will always fail because of an error in line 7.
• D、 Compilation will always fail because of an error in line 8.

第6题：

class A {   public String toString （） {   return “4”；   }   }   class B extends A {   8. public String toString （） {   return super.toString（） + “3”；   }   }   public class Test {   public static void main（Stringargs） {   System.out.printIn（new B（））；   }   }   What is the result？（）  

• A、 Compilation succeeds and 4 is printed.
• B、 Compilation succeeds and 43 is printed.
• C、 An error on line 9 causes compilation to fail.
• D、 An error on line 14 causes compilation to fail.
• E、 Compilation succeeds but an exception is thrown at line 9.

第7题：

abstract class abstrctIt {   abstract float getFloat （）；   }   public class AbstractTest extends AbstractIt {   private float f1= 1.0f；   private float getFloat （） {return f1；}   }   What is the result？ （）

• A、 Compilation is successful.
• B、 An error on line 6 causes a runtime failure.
• C、 An error at line 6 causes compilation to fail.
• D、 An error at line 2 causes compilation to fail.

第8题：

第9题：

package foo；  import java.util.Vector； private class MyVector extends Vector {  int i = 1；  public MyVector（） {  i = 2； } }  public class MyNewVector extends MyVector {  public MyNewVector（） {  i = 4；  }  public static void main（String args[]） {  MyVector v = new MyNewVector（）；  }  }  What is the result？（）

• A、 Compilation succeeds.
• B、 Compilation fails because of an error at line 5.
• C、 Compilation fails because of an error at line 6.
• D、 Compilation fails because of an error at line 14.
• E、 Compilation fails because of an error at line 17.

第10题：

package foo；   import java.util.Vector；   private class MyVector extends Vector {  int i = 1；   public MyVector（） {   i = 2；  }   }   public class MyNewVector extends MyVector {   public MyNewVector （） {   i = 4；   }   public static void main （String args ） {    MyVector v = new MyNewVector（）；   }   }   The file MyNewVector.java is shown in the exhibit.  What is the result？（）

• A、 Compilation will succeed.
• B、 Compilation will fail at line 5.
• C、 Compilation will fail at line 6.
• D、 Compilation will fail at line 14.
• E、 Compilation will fail at line 17.