Given：

A programmer is developing a class Key， that will be used as a key in a standard java.util.HashMap. Which two methods should be overridden to assure that Key works correctly as a key？（）

单项选择题Given： What is the appropriate definition of the hashCode method in class Person？（）

A.return super.hashCode（）；
B.return name.hashCode（） + age * 7；
C.return name.hashCode（） + comment.hashCode（） / 2；
D.return name.hashCode（） + comment.hashCode（） / 2 - age * 3；

单项选择题Click the Exhibit button. Which statement is true about the set variable on line 12？（）

A.The set variable contains all six elements from the coll collection， and the order is guaranteed to be preserved.
B.The set variable contains only three elements from the coll collection， and the order is guaranteed to be preserved.
C.The set variable contains all six elements from the coll collection， but the order is NOT guaranteed to be preserved.
D.The set variable contains only three elements from the coll collection， but the order is NOT guaranteed to be preserved.

多项选择题Click the Exhibit button. What two must the programmer do to correct the compilation errors？（）

A.insert a call to this（） in the Car constructor
B.insert a call to this（） in the MeGo constructor
C.insert a call to super（） in the MeGo constructor
D.insert a call to super（vin） in the MeGo constructor
E.change the wheelCount variable in Car to protected

单项选择题Given： What is the result？（）

A.Compilation fails.
B.Cannot add Toppings
C.The code runs with no output.
D.A NullPointerException is thrown in Line 4.

单项选择题A team of programmers is involved in reviewing a proposed design for a new utility class. After some discussion， they realize that the current design allows other classes to access methods in the utility class that should be accessible only to methods within the utility class itself. What design issue has the team discovered？（）

A.Tight coupling
B.Low cohesion
C.High cohesion
D.Loose coupling
E.Weak encapsulation
F.Strong encapsulation