多选题Which of the following statements are true？（）AThe equals（） method determines if reference values refer to the same object.BThe == operator determines if the contents and type of two separate objects match.CThe equals（） method returns true only when the

第1题：

1. public class Person {  2. private String name；  3. public Person（String name） { this.name = name； }  4. public boolean equals（Person p） {  5. return p.name.equals（this.name）；  6. }  7. }  Which is true？（） 

• A、 The equals method does NOT properly override the Object.equals method.
• B、 Compilation fails because the private attribute p.name cannot be accessed in line 5.
• C、 To work correctly with hash-based data structures， this class must also implement the hashCode method.
• D、 When adding Person objects to a java.util.Set collection， the equals method in line 4 will prevent duplicates.

第2题：

Which of the following statements about variables and scope are true？（） 

• A、 Local variables defined inside a method are destroyed when the method is exited.
• B、 Local variables are also called automatic variables.
• C、 Variables defined outside a method are created when the object is constructed.
• D、 A method parameter variable continues to exist for as long as the object is needed in which the method is defined.

第3题：

第4题：

public class Person {  private name；  public Person（String name） {  this.name = name；  }  public boolean equals（Object o） {  if（ !o instanceof Person ） return false；  Person p = （Person） o；  return p.name.equals（this.name）；  }  }  Which is true？（） 

• A、 Compilation fails because the hashCode method is not overridden.
• B、 A HashSet could contain multiple Person objects with the same name.
• C、 All Person objects will have the same hash code because the hashCode method is not overridden.
• D、 If a HashSet contains more than one Person object with name=”Fred”， then removing another person， also with name=”Fred”， will remove them all.

第5题：

Which of the following statements are true？（） 

• A、 The equals（） method determines if reference values refer to the same object.
• B、 The == operator determines if the contents and type of two separate objects match.
• C、 The equals（） method returns true only when the contents of two objects match.
• D、 The class File overrides equals（） to return true if the contents and type of two separate objects        match.

第6题：

Which two statements are true regarding the return values of property written hashCode and equals methods from two instances of the same class？（）

• A、 If the hashCode values are different， the objects might be equal.
• B、 If the hashCode values are the same， the object must be equal.
• C、 If the hashCode values are the same， the objects might be equal.
• D、 If the hashCode values are different， the objects must be unequal.

第7题：

Given that b and c refer to instances of wrapper classes， which two statements are true？（）

• A、 b.equals（b） returns true.
• B、 b.equals（c） returns the same result as b == c.
• C、 b.eqials（c） can return false even if c.equals（b） returns true.
• D、 b.equals（c） throws an exception if b and c are different wrapper types.
• E、 b.equals（c） returns false if the type of wrapper objects being compared are different.

第8题：

第9题：

Given a class whose instances， when found in a collection of objects， are sorted by using the compareTo（） method， which two statements are true？（）

• A、The class implements java.lang.Comparable.
• B、The class implements java.util.Comparator.
• C、The interface used to implement sorting allows this class to define only one sort sequence.
• D、The interface used to implement sorting allows this class to define many different sort sequences.

第10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.