单选题Given: What is the result?（）A Compilation fails.B exception is thrown at runtime.C The attribute id in the ItemTest object remains unchanged.D The attribute id in the ItemTest object is modified to the new value.E A new ItemTest object is created

第1题：

public class Threads5 {  public static void main （String[] args） {  new Thread（new Runnable（） {  public void run（） {  System.out.print（”bar”）；  } }）.start（）；  }  }  What is the result？（） 

• A、 Compilation fails.
• B、 An exception is thrown at runtime.
• C、 The code executes normally and prints “bar”.
• D、 The code executes normally， but nothing prints.

第2题：

11. public static void main（String[] args） {  12. Object obj = new Object（） {  13. public int hashCode（） {  14. returns 42； 15. }  16. }；  17. System.out.println（obj.hashCode（））；  18. }    What is the result？ （） 

• A、 42
• B、 An exception is thrown at runtime.
• C、 Compilation fails because of an error on line 12.
• D、 Compilation fails because of an error on line 16.
• E、 Compilation fails because of an error on line 17.

第3题：

第4题：

try {  if （（new Object））（.equals（（new Object（）））） {  System.out.println（“equal”）；  }else{  System.out.println（“not equal”）；  }  }catch （Exception e） {  System.out.println（“exception”）；  }   What is the result？ （） 

• A、 equal
• B、 not equal
• C、 exception
• D、 Compilation fails.

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.

第6题：

public class ItemTest {  private final mt id；  public ItemTest（int id） { this.id = id； }  public void updateId（int newId） { id = newId； }  public static void main（String[] args） {  ItemTest fa = new ItemTest（42）；  fa.updateId（69）；  System.out.println（fa.id）；  }  }  What is the result？（） 

• A、 Compilation fails.
• B、 An exception is thrown at runtime.
• C、 The attribute id in the Item object remains unchanged.
• D、 The attribute id in the Item object is modified to the new value.
• E、 A new Item object is created with the preferred value in the id attribute.

第7题：

What happens when thread X executes a wait（） method on object A， without owning object A’s lock？（）  

• A、 Compilation fails.
• B、 An exception is thrown.
• C、 The wait（） method has no effect.
• D、 Thread X receives the lock immediately.
• E、 Object A moves the thread to the wait pool.

第8题：

public class Threads3 implements Runnable {  public void run（） {  System.out.print（”running”）；  }  public static void main（String[] args） {  Thread t = new Thread（new Threads3（））；  t.run（）；  t.run（）；  t.start（）；  }  }  What is the result？（） 

• A、 Compilation fails.
• B、 An exception is thrown at runtime.
• C、 The code executes and prints “running”.
• D、 The code executes and prints “runningrunning”.
• E、 The code executes and prints “runningrunningrunning”.

第9题：

public class Drink implements Comparable {  public String name；  public int compareTo（Object o） {  return 0；  }  }  and：  Drink one = new Drink（）；  Drink two = new Drink（）；  one.name= “Coffee”；  two.name= “Tea”；  TreeSet set = new TreeSet（）；  set.add（one）；  set.add（two）；  A programmer iterates over the TreeSet and prints the name of each Drink object. What is the result？（） 

• A、 Tea
• B、 Coffee
• C、 Coffee Tea
• D、 Compilation fails.
• E、 The code runs with no output.
• F、 An exception is thrown at runtime.

第10题：

import java.io.*；  public class Forest implements Serializable {  private Tree tree = new Tree（）；  public static void main（String [] args） {  Forest f= new Forest（）；  try {  FileOutputStream fs = new FileOutputStream（”Forest.ser”）；  ObjectOutputStream os = new ObjectOutputStream（fs）；  os.writeObject（f）； os.close（）；  } catch （Exception ex） { ex.printStackTrace（）； }  }  }  class Tree { }  What is the result？（） 

• A、 Compilation fails.
• B、 An exception is thrown at runtime.
• C、 An instance of Forest is serialized.
• D、 A instance of Forest and an instance of Tree are both serialized.