Which of the following is correct implementation code for the compareTo method in the ExpertPlayer class?
1 answer:
Complete Question:
The complete question is shown in uploaded image one and two.
Answer:
Answer is E
Explanation:
In order to gain understanding of this answer let look at each code line by line
Considering Method one :
public int compareTo(Object obj)
{
This is the deceleration of the method.
ExpertPlayer rhs = (ExpertPlayer) obj;
On this line of code above an object (obj) that is passed into the method ( compareTo)is converted to type ExpertPlayer and is being assigned to a variable(rhs) of type ExpertPlayer
if(myRating == rhs.myRating) return 0;
else if(myRating < rhs.myRating) return 1;
else return 1;
}
This if conditional statement above will comparing the private variable myRating defined on ExpertPlayer with the private variable on the instance of the ExpertPlayer(i.e rhs.myRating)
some might ask why is compareTo method accessing myRating which is private variable without getters or setters method. This is because the method (compareTo )and the variable(myRating) are defined in the same class.
Looking at this conditional statement we see that
if myRating == rhs.Rating it will return 0
if myRating < rhs.Rating it will return -1 a negative value
if myRating > rhs.Rating it will return 1 a positive value
Considering Method two
public int compareTo(Object obj)
{
As usual this code above is the deceleration of the method.
ExpertPLayer rhs = (ExpertPlayer) obj;
On this line of code above an object (obj) that is passed into the method ( compareTo)is converted to type ExpertPlayer and is being assigned to a variable(rhs) of type ExpertPlayer
return myRating – rhs.myRating;
}
On this line of code above a variable of an instance of ExpertPlayer class (i.e rhs.myRating) is subtracted from a private variable ( myrating) in ExpertPlayer class
Now looking at this code we see that if they are equal(i.e if myrating is equal to rhs.myRating) 0 will be returned
if myRating is less than rhs.myRating a negative value is returned
and if myRating is greater than rhs.myRating a positive value is return
comparing this with the first method we see that they are the same.
Considering Method Three
public int compareTo(Object obj)
{
As usual this code above is the deceleration of the method.
ExpertPLayer rhs = (ExpertPlayer) obj;
On this line of code above an object (obj) that is passed into the method ( compareTo)is converted to type ExpertPlayer and is being assigned to a variable(rhs) of type ExpertPlayer
if (getName().equals(rhs.getName()))
return 0;
else if (getName().compareTo(rhs.getName()) < 0)
return -1;
else
return 1;
}
On the above snippet of code myName a private variable gotten using getName() method from the HumanPlayer class which extended by ExpertPlayer class is compared with the myName variable of the instance of ExpertPlayer (i.e rhs) gotten using rhs.getName()
looking at this code above we see that it produces the same result as method one and two in that if the two compared items are the same it will return 0, if getName() is less than rhs.getName() it will return -1 ,which is a negative value, and
if getName() is greater than rhs.getName() it will return 1 which is a positive value.
You might be interested in