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The output produced by this program is shown below:

Tom TOM Joe JOE Bill BILL

If that was your answer, you probably already understand most of the material covered in this module. In that case, you might consider skipping this moduleand moving on to the next module. If that wasn't your answer, you should probably continue with your study of this module.

Similar to previous programs

The overall structure of the program in Listing 1 is similar to programs that I have discussed in previous modules. Therefore, I will concentrate onthose aspects of this program that differentiate it from the programs in previous modules.

A new LinkedList object

The code in Listing 2 instantiates a new LinkedList object and passes that object's reference to a method named fillIt where it is populated with the names of several people.

Listing 2 . A new LinkedList object.
ref = new LinkedList(); Populator.fillIt(ref);

The LinkedList class is one of the concrete implementation classes of the Collections Framework. This class implements the Collection interface and the List interface. Here is part of what Oracle has to say about the LinkedList class:

"Linked list implementation of the List interface. Implements all optional list operations, and permits all elements (including null). Inaddition to implementing the List interface, the LinkedList class provides uniformly named methods to get, remove and insert an element at thebeginning and end of the list. These operations allow linked lists to be used as a stack, queue, or double-ended queue (deque)."

Populating the List

The code in Listing 3 shows the fillIt method that is used to populate the list with references to six different String objects.

The add method is used to add each new element to the end of the list. As you can see, the elements are added to the list in no particular order withrespect to their values.

Listing 3 . The fillIt method.
class Populator{ public static void fillIt(Collection ref){ref.add("Joe"); ref.add("Bill");ref.add("Tom"); ref.add("JOE");ref.add("BILL"); ref.add("TOM");}//end fillIt() }//end class Populator

Displaying the list

Although I didn't bother to do so in this program, if an iterator were to be used to access and display the elements in the list following the invocation ofthe fillIt method, the result would be as shown below:

Joe Bill Tom JOE BILL TOM

As you can see, this is the same as the order in which the elements are added to the list. The first element is added to the list at index value 0 and thesixth element is added to the list at index value 5.

Sort the list

The code shown in Listing 4 is new to this module. This code uses the sort method of the Collections class, along with a Comparator object to sort the contents of the list.

Listing 4 . Sort the list.
Collections.sort((List)ref, new TheComparator());
The sort method expects to receive an incoming parameter of type List . Therefore, it was necessary to cast the reference from type Collection to type List .

A very important point

Unlike the programs in previous modules that simply extracted the contents of the collection into an array and sorted the array, this codeactually rearranges the contents of the list according to the sorting rules.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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