Which two demonstrate an “is a” relationship？ （）

A

 public interface Person{}  public class Employee extends Person{}

B

 public interface Shape{}  public class Employee extends Shape{}

C

 public interface Color{}  public class Employee extends Color{}

D

 public class Species{}  public class Animal （private Species species；）

E

 interface Component{}  Class Container implements Component （  Private Component[ ] children；  ）

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• public class Yippee2 {  static public void main（String [] yahoo） {  for（int x= 1； xSystem.out.print（yahoo[x] + “ “）；  }  }  }  and the command line invocation： java Yippee2 a b c What is the result？（） 

  A、a b

  B、b c

  C、a b c

  D、 Compilation fails.

  E、 An exception is thrown at runtime.

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• Consider the following class：     class Test（int i） {     void test（int i） {  System.out.println（“I am an int.”）； }    void test（String s） {   System.out.println（“I am a string.”）；     }          public static void main（String args） {    Test t=new Test（）；     char ch=“y”；    t.test（ch）；     }      }     Which of the statements below is true？（）

  A、 Line 5 will not compile， because void methods cannot be overridden.

  B、 Line 12 will not compile， because there is no version of test（） that rakes a charargument.

  C、 The code will compile but will throw an exception at line 12.

  D、 The code will compile and produce the following output： I am an int.

  E、 The code will compile and produce the following output： I am a String.

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• Which two changes， taken together， would guarantee the output： 1， 2， 3， 4， 5？（）

  A

  move the line 12 print statement into the foo（） method

  B

  change line 7 to public synchronized void go（）{

  C

  change the variable declaration on line 2 to private volatile int x；

  D

  wrap the code inside the foo（） method with a synchronized（this） block

  E

  wrap the for loop code inside the go（） method with a synchronized block synchronized（this）{//for loop code here}

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• public class X {  public X aMethod（） { return this；}  }  public class Y extends X {  }  Which two methods can be added to the definition of class Y？（）

  A

   public void aMethod（） {}

  B

   private void aMethod（） {}

  C

   public void aMethod（String s） {}

  D

   private Y aMethod（） { return null； }

  E

   public X aMethod（） { return new Y（）； }

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• Assume that country is set for each class.  Given：  10. public class Money {  11. private String country， name；  12. public getCountry（） { return country； }  13.}  and：  24. class Yen extends Money {  25. public String getCountry（） { return super.country； }  26. }  27.  28. class Euro extends Money {  29. public String getCountry（String timeZone） {  30. return super.getCountry（）；  31. }  32. }  Which two are correct？（）

  A

   Yen returns correct values.

  B

   Euro returns correct values.

  C

   An exception is thrown at runtime.

  D

   Yen and Euro both return correct values.

  E

   Compilation fails because of an error at line 25.

  F

   Compilation fails because of an error at line 30.

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