多选题Which three statements are true?（）AA final method in class X can be abstract if and only if X is abstract.BA protected method in class X can be overridden by any subclass of X.CA private static method can be called only within other static methods in c

第1题：

Which two of statements are true？（）

• A、It is possible to synchronize static methods.
• B、When a thread has yielded as a result of yield（）， it releases its locks.
• C、When a thread is sleeping as a result of sleep（）， it releases its locks.
• D、The Object.wait（） method can be invoked only from a synchronized context.
• E、The Thread.sleep（） method can be invoked only from a synchronized context.
• F、When the thread scheduler receives a notify（） request， and notifies a thread， that thread immediately releases its lock.

第2题：

package foo； public class Outer （  public static class Inner （  ）  ）   Which statement is true？ （） 

• A、 An instance of the Inner class can be constructed with “new Outer.Inner （）”
• B、 An instance of the inner class cannot be constructed outside of package foo.
• C、 An instance of the inner class can only be constructed from within the outer class.
• D、 From within the package bar， an instance of the inner class can be constructed with “new inner（）”

第3题：

It is desirable that a certain method within a certain class can only be accessed by classes that are defined within the same package as the class of the method. How can such restrictions be enforced？（）  

• A、Mark the method with the keyword public.
• B、Mark the method with the keyword protected.
• C、Mark the method with the keyword private.
• D、Mark the method with the keyword package.
• E、Do not mark the method with any accessibility modifiers.

第4题：

Which will declare a method that is available to all members of the same package and can be referenced without an instance of the class？（）  

• A、 Abstract public void methoda（）；
• B、 Public abstract double methoda（）；
• C、 Static void methoda（double d1）{}
• D、 Public native double methoda（）  {}
• E、 Protected void methoda（double d1）  {}

第5题：

public class TestSeven extends Thread {  private static int x；  public synchronized void doThings（） {  int current = x；  current++；  x = current；  }  public void run（） {  doThings（）；  }  }  Which is true？（） 

• A、 Compilation fails.
• B、 An exception is thrown at runtime.
• C、 Synchronizing the run（） method would make the class thread-safe.
• D、 The data in variable “x” are protected from concurrent access problems.
• E、 Declaring the doThings（） method as static would make the class thread-safe.
• F、 Wrapping the statements within doThings（） in a synchronized（new Object（）） {} block would make the class thread-safe.

第6题：

public class SyncTest {  private int x；  private int y；  public synchronized void setX （int i） （x=1；）  public synchronized void setY （int i） （y=1；）  public synchronized void setXY（int 1）（set X（i）； setY（i）；）  public synchronized Boolean check（） （return x !=y；）  }  Under which conditions will check （） return true when called from a different class？

• A、 Check（） can never return true.
• B、 Check（） can return true when setXY is called by multiple threads.
• C、 Check（） can return true when multiple threads call setX and setY separately.
• D、 Check（） can only return true if SyncTest is changed to allow x and y to be set separately.

第7题：

Which two statements are true about the hashCode method？（）

• A、The hashCode method for a given class can be used to test for object equality and object inequality for that class.
• B、The hashCode method is used by the java.util.SortedSet collection class to order the elements within that set.
• C、The hashCode method for a given class can be used to test for object inequality， but NOT objecte quality， for that class.
• D、The only important characteristic of the values returned by a hashCode method is that the distribution of values must follow a Gaussian distribution.
• E、The hashCode method is used by the java.util.HashSet collection class to group the elements within that set into hash buckets for swift retrieval.

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第13题：

public class SyncTest （  private int x；  private int y；  private synchronized void setX （int i） （x=1；）  private synchronized void setY （int i） （y=1；）  public void setXY（int 1）（set X（i）； setY（i）；）  public synchronized Boolean check（） （return x !=y；）  ）  Under which conditions will check （） return true when called from a different class？   

• A、 Check（） can never return true.
• B、 Check（） can return true when setXY is called by multiple threads.
• C、 Check（） can return true when multiple threads call setX and setY separately.
• D、 Check（） can only return true if SyncTest is changed to allow x and y to be setseparately.

第14题：

Which the following two statements are true？（）

• A、 An inner class may be declared as static.
• B、 An anonymous inner class can be declared as public.
• C、 An anonymous inner class can be declared as private.
• D、 An anonymous inner class can extend an abstract class.
• E、 An anonymous inner class can be declared as protected.

第15题：

Which statement is true？（）

• A、 An anonymous inner class may be declared as final.
• B、 An anonymous inner class can be declared as private.
• C、 An anonymous inner class can implement multiple interfaces.
• D、 An anonymous inner class can access final variables in any enclosing scope.
• E、 Construction of an instance of a static inner class requires an instance of the enclosing outer class.

第16题：

Which declaration prevents creating a subclass of an outer class？（）  

• A、 Static class FooBar{}
• B、 Private class FooBar{}
• C、 Abstract public class FooBar{}
• D、 Final public class FooBar{}
• E、 Final abstract class FooBar{}

第17题：

Which two statements are true about using the isUserInRole method to implement security in a Java EEapplication？（）

• A、It can be invoked only from the doGet or doPost methods.
• B、It can be used independently of the getRemoteUser method.
• C、Can return "true" even when its argument is NOT defined as a valid role name in the deployment descriptor.
• D、Using the isUserInRole method overrides any declarative authentication related to the method in which it is invoked.

第18题：

Which three statements are true?（）

• A、A final method in class X can be abstract if and only if X is abstract.
• B、A protected method in class X can be overridden by any subclass of X.
• C、A private static method can be called only within other static methods in class X.
• D、A non-static public final method in class X can be overridden in any subclass of X.
• E、A public static method in class X can be called by a subclass of X without explicitly referencing the class X.
• F、A method with the same signature as a private final method in class X can be implemented in a subclass of X.
• G、A protected method in class X can be overridden by a subclass of X only if the subclass is in the same package as X.

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