DB Design Question From A Novice

I need help in structuring the code for a javabean that I'm writing. Basically, I want to have the bean run several different types of DB queries (e.g. "check username and password", "list the groups that the player is in", "list player attributes", etc).
The approach I started taking (out of simplicity) was to write a new method for each type of query I wanted to run. In other words, I wrote one method to "check username and password" and another to "list the groups that the player is in", etc. However, I noticed that this caused a lot of repeating in the code (e.g. con.createStatement(); and stmt.executeQuery() for all these methods). I posted this question on a different forum and someone suggested writing a generic method (that takes a String parameter containing a database query) and putting the output into a Vector object and returning that to the calling method. My question is: "is this the 'common' way of doing things?" Another question is, "are both approaches acceptable?" Personally, I think it seems a little easier to use the approach I started using but, I have to admit, all the repeating code troubles me. I'm learning this on my own so I don't really have someone to ask in person about this. I'm looking for the advice of someone with some experience in these matters. Thanks in advance for any help you can provide.

My question is: "is this
the 'common' way of doing things?" Basically yes. There are variations but the general idea is the same.
You might want to look at this...
http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
And this....
http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html
Another question
is, "are both approaches acceptable?" Your original approach would become unmangeable in a larger application. But other than that yes.
Personally, I
think it seems a little easier to use the approach I
started using but, I have to admit, all the repeating
code troubles me. And the repeating code, from the perspective of learning, is probably a good thing to a certain extent. It allows you to recognize patterns and thus question alternatives. And then when you move on to something else more sophisticated you will understand why it better/appropriate as opposed to someone who just does it one way without ever understanding why. (And for small applications you do use exactly the method you are doing rather than using more sophisticated and thus complex solutions.) Additionally you are more likely to be able to more quickly debug applications because you will be able to seperate out core problems relating to the database versus problems that are related to the intermediate layers.

Similar Messages

Silly questions from a novice?

I have just downloaded i-tunes onto a computer and I am having several problems.
1. After I have imported/ripped a cd into i-tunes, the songs skip through without playing.
2. I went to the apple website and installed the latest i-tunes 6, and when I tried to import a cd, an error report came up, the one saying send error report etc.
3. I put a few mixes from a website into i-tunes and it plays them right through, but when I try to put them onto ipod it says that the songs cannot be recognised?
4. How do I take unwanted songs off of my ipod?
Is this a problem with the computer that I am using? And if so can I go to another computer and install my i-tunes there. Or can you only download i-tunes onto one comp?
So many questions I know, but I really dont have a clue and want to get some music onto my ipod.
Thanks in advance.

.4 To remove unwanted songs from your ipod connect your ipod to your computer, open itunes, then click on the ipod icon.
Now all the songs on your ipod are listed to the right. Simply select the songs you want to remove, click on edit->remove.
I believe they will be automatically removed from your playlists as well.
good luck!

A few questions from a novice

Hi all
My leopard was an unexpected gift from my parents for my daughter and I, I'm sure you can all imagine how delighted we have been and what an exciting new world that has begun to open up for us.
However I have hit a wall a few times over certain features and struggle to understand how to resolve these problems.
I find online advice either assumes I have a knowledge of mac's I just don't have or apple's own solutions to be a bit Ronald MacDonaldspeak: "Hey great, now you've got a mac, cool, have a nice day.."
I've made two phone calls, for 30 minutes, and then an hour, to technical support who couldn't even get my password going.. ( though they did make a point of telling me I was getting it wrong when I wasn't!)
Anyway, when you've stopped laughing out there guys can any of you help me with a few points:
a.)I can recieve e mail on my mac address but it won't send it.
b.)A friend has sent me a video greeting on my old BT Yahoo e mail address but I can't view it despite downloading windows Media for mac which started going on about something called Stuffit???!!
c.)Whenever I try to go online it fails and I have to restart once or twice.
d.) I can't get pictures on a CD onto i photo.
e.) I want to do sound and cam to friends on msn ,Yahoo messenger etc.I don't know anybody on i chat nor can my non-apple user friends download a version of i chat to connect from their side with mine - is this merely political, that it doesn't work because of some rivalry between the rest of the cyber world and apple?
If you can help I'd be most grateful but remember I really don't understand jargon jargon!
Message was edited by: kevinh08

kevinh08 wrote:
a.)I can recieve e mail on my mac address but it won't send it.
Check the settings for your "Outgoing mail server (SMTP)". The information for that should be available from your ISP.
b.)A friend has sent me a video greeting on my old BT Yahoo e mail address but I can't view it despite downloading windows Media for mac which started going on about something called Stuffit???!!
You may want to check into [Flip4Mac|http://www.flip4mac.com/wmv_download.htm], which will allow you to view Windows Media videos with Quicktime on the Mac.
c.)Whenever I try to go online it fails and I have to restart once or twice.
Can you elaborate on that? What happens when it fails?
d.) I can't get pictures on a CD onto i photo.
Again, more information would be helpful. You should be able to simply drag the pictures from the CD onto the iPhoto window. Again, what happens when it fails?
e.) I want to do sound and cam to friends on msn ,Yahoo messenger etc.I don't know anybody on i chat nor can my non-apple user friends download a version of i chat to connect from their side with mine - is this merely political, that it doesn't work because of some rivalry between the rest of the cyber world and apple?
iChat works with AOL IM, but I believe not with MSN or Yahoo. I agree that it's dumb that the two camps aren't compatible, but it's not an Apple vs The World situation.

Rendering question from a novice in the middle of an editing project

Hi,
I'm editing a 50 min program that is a live 2 camera shoot. Both consumer dv cameras, one new & one five or more years old. So as you can imagine, theres a real quality diff between the cameras, both in brightness values as well as color values.
So I tried experimenting in FCP color correction, just picking a shot & fooling around with brightness & color. Trying to get a feel for how they work etc. I never intended to render any of it. Then I went back to cutting for a few days & suddenly the program was "auto rendering". I didnt see a way to undo that at the time, so I've since continued cutting & saving, but now I'm ready to really tackle color correcting.
Before I do any wholesale correction to a camera shot, I want to undo all of that testing that the program auto rendered.
How do I do that?
Thanks
G5 tower Mac OS X (10.4.2)

Before I do any wholesale correction to a camera shot, I want to undo all of that testing that the program auto rendered.
Well, if you want to undo all of what you've done - that is, filters & rendering - select all the affected clips and use the Remove Attributes feature.
To access that feature, either Control-click and select it from the contextual menu or press Option-Command-V on your keyboard. In the dialog box that comes up, select 'Filters' from the Video list, then click OK.
If you only want to undo the rendering (but leave the filters applied for further tweaking), a neat trick I learned here is to simply use the Clip Enable toggle. That is, select your clips and press Control-B once to disable them, then press Control-B again to enable those clips.
(In case it's not obvious, toggling clips trashes all associated render files)

Question from a novice user

Hi, I need to develop an application that
reads and writes complex data-centric XML
documents to an Oracle database.
I know about XML SQL Utility for Java but...
which choice do I have if I can't use the Java environment?
Should I write all my code or there is some other helpful utility? What about PLSXML?
Thanks in advance for any help,
Carla Delmonte
null

If you have Oracle8i, then you can use the "xmlgen" package that comes with the Oracle XML SQL Utility (and wrappers its Java functionality in a PL/SQL package) to do everything you can do from a Java program from PL/SQL. The XMLGEN package is created by running the "xmlgenpkg.sql" script in the ./lib directory that comes with the Oracle XML SQL Utility.
The PL/SQL package function xmlgen.insertXML() should do what you need.
The XML Parser for PL/SQL (not the same as PLSXML utilities) also is a PL/SQL wrapper on the Java XML Parser, and exposes the full functionality of the Java implementation through a set of easy-to-use PL/SQL packages.
PLSXML is not really an option since it does not support putting XML into the database, only getting it out.

Questions from a novice

several basic questions that my java programmer's reference isn't making clear to me:
a. is String a primitve datatype? or is it treated as an object
b. whatever String happens to be, can there be a List of Strings?
c. if it's not right to have List li = new List(); that is instantiate a list, how come it's possible to instantiate something that implements a list e.g. List li = new classa.getSomeList();
thanks a lot.
-leo

a. is String a primitve datatype? or is it treated as an objectAn Object
b. whatever String happens to be, can there be a List of Strings?Yes
c. if it's not right to have List li = new List(); that is instantiate a list, how come it's possible to instantiate something that implements a list e.g. List li = new classa.getSomeList();List is an interface. Interfaces cannot be instantiated but classes that implement the List interface can. i.e.
List li = new ArrayList(); // ArrayList implements the List interfaceDave

Design question about instant download from

Hi All,
Here is a design question for you:
Background:
The application we built is being upgraded from time to time and we send it to our users.
our users use it on a network so there is only one file to upgrade (and being done by the sys admin)
We send them a �patch�; actually, it�s a new version of the application they place it in the relevant folder and continue to work with a new version.
Problems:
1. We send them the patch via email - sometimes it takes a while until they read their email and at they are using an �old version of the system�.
2. Some of them are not computer savvy (when it�s not the sys admin) and we need to guide them as where exactly to place the file (there are 3 files)
Our (conceptual never build yet) Solution:
Build a program just like Norton antivirus (or other) that prompts the user from the task bar (next to the clock) that a new version is available and by
clicking once it will automatically download the file and store it in the correct folder.
Question:
1. Did anyone try anything like this before (or something like) who can tell me about it?
2. Do you think this kind of system will work for us?
3. Does anyone have a better solution?
Thanks
Peter

Java WebStart is the deployment technique suited for your purposes.
The deployment will be done via a webserver running a jnlp servlet (provided).
The applications may either run offline, or check online for automatic updates.
You have several configuration options.
ArgoUML and jEdit are two open source apps delivered this way.
Your app will need to be adapted though.
And your customers need an online browser with installed jvm.

Design question: Scheduling a Variable-timeslot Resource

I originally posted this in general java programming, because this seemed like a more high-level design descussion. But now I see some class design questions. Please excuse me if this thread does not belong here (this is my first time using the forum, save answering a couple questions).
Forum,
I am having trouble determining a data structure and applicable algorithm (actually, even more general than the data structure -- the general design to use) for holding a modifiable (but more heavily read/queried than updated), variable-timeslot schedule for a given resource. Here's the situation:
Let's, for explanation purposes, say we're scheduling a school. The school has many resources. A resource is anything that can be reserved for a given event: classroom, gym, basketball, teacher, janitor, etc.
Ok, so maybe the school deal isn't the best example. Let's assume, for the sake of explanation, that classes can be any amount of time in length: 50 minutes, 127 minutes, 4 hours, 3 seconds, etc.
Now, the school has a base operation schedule, e.g. they're open from 8am to 5pm MTWRF and 10am to 2pm on saturday and sunday. Events in the school can only occur during these times, obviously.
Then, each resource has its own base operation schedule, e.g. the gym is open from noon to 5pm MTWRF and noon to 2pm on sat. and sun. The default base operation schedule for any resource is the school which "owns" the resource.
But then there are exceptions to the base operation schedule. The school (and therefore all its resources) are closed on holidays. The gym is closed on the third friday of every month for maintenance, or something like that. There are also exceptions to the available schedule due to reservations. I've implemented reservations as exceptions with a different status code to simplify things a little bit: because the basic idea is that an exception is either an addition to or removal from the scheduleable times of that resource. Each exception (reservation, closed for maintenance, etc) can be an (effectively) unrestricted amount of time.
Ok, enough set up. Somehow I need to be able to "flatten" all this information into a schedule that I can display to the user, query against, and update.
The issue is complicated more by recurring events, but I think I have that handled already and can make a recurring event be transparent from the application point of view. I just need to figure out how to represent this.
This is my current idea, and I don't like it at all:
A TimeSlot object, holding a beginning date and ending date. A data structure that holds list of TimeSlot objects in order by date. I'd probably also hold an index of some sort that maps some constant span of time to a general area in the data structure where times around there can be found, so I avoid O(n) time searching for a given time to find whether or not it is open.
I don't like this idea, because it requires me to call getBeginningDate() and getEndDate() for every single time slot I search.
Anyone have any ideas?

If I am correct, your requirement is to display a schedule, showing the occupancy of a resource (open/closed/used/free and other kind of information) on a time line.
I do not say that your design is incorrect. What I state below is strictly my views and should be treated that way.
I would not go by time-slot, instead, I would go by resource, for instance the gym, the class rooms (identified accordingly), the swimming pool etc. are all resources. Therefore (for the requirements you have specified), I would create a class, lets say "Resource" to represent all the resources. I would recommend two attributes at this stage ("name" & "identifier").
The primary attribute of interest in this case would be a date (starting at 00:00hrs and ending at 24:00hrs.), a span of 24hrs broken to the smallest unit of a minute (seconds really are not very practical here).
I would next encapsulate the availability factor, which represents the concept of availability in a class, for instance "AvailabilityStatus". The recommended attributes would be "date" and "status".
You have mentioned different status, for instance, available, booked, closed, under-maintainance etc. Each of these is a category. Let us say, numbered from 0 to n (where n<128).
The "date" attribute could be a java.util.Date object, representing a date. The "status", is byte array of 1440 elements (one element for each minute of the day). Each element of the byte array is populated by the number designation of the status (i.e, 0,1,2...n etc.), where the numbers represent the status of the minute.
The "Resource" class would carry an attribute of "resourceStatus", an ordered vector of "ResourceStatus" objects.
The object (all the objects) could be populated manually at any time, or the entire process could be automated (that is a separate area).
The problem of representation is over. You could add any number of resources as well as any number of status categories.
This is a simple solution, I do not address the issues of querying this information and rendering the actual schedule, which I believe is straight forward enough.
It is recognized that there are scope for optimizations/design rationalization here, however, this is a simple and effective enough solution.
regards
[email protected]

Why can't I post a question from my new system?

Hello All:
I was just trying to post a question from my new mbp but it wouldn't allow me to do anything. It continually gave me a message highlighted in 'red' that i was;t allowed to modify or post anything. I've been asking questions for quite a while and have never seen this. I also happen to have my older bmp, also logged onto the 'Apple Discussions' site, open beside me. Can anyone explain this to me please? BTW, my new system obviously has Yosemite on it while my older bmp has Lion. Thanks in advance, to all those who respond.
Regards,
Ciaochiao

ChitlinsCC, I'm adding your reloaders to my article on how to make using ASC easier.
Here is my ASC work flow...
1) I login.
2) Block the automatic 30 minute logout.
     Unless you do something every thirty minutes you get logged out. The forum software waits to tell you this as long as it can to keep you in suspense ;-) . Filling out a reply is the exception to the thirty minute window.
        Start an auto reloader.
Safari = SafariTabReloader
Firefox = ReloadEvery: "Reload web pages automatically"
Others = Reloaders | Cerberus - Support Center
You need to pick a page that will reload over time without stalling out. It's ASC. I've found my profile display the best to use. I get my Profile page after some logins. It's ASC. Change rccharles to your apple id.
https://discussions.apple.com/people/rccharles?view=discussions
Reply technique
Open a new browser window. Pick some discussion. Open a reply window. As long as this reply window is open, you will stay logged in. The 30 minute times is reset as needed by the ASC software.
3) I open another window to do my normal ASC browsing.
4) I have a FireFox bookmark to goto the discussions that I have participated in. I've modified it to add on the content stuff.
         turingtest2 recommends. Change rccharles to your apple id:
https://discussions.apple.com/people/rccharles/content?filterID=participated~obj ecttype~objecttype%5Bthread%5D
5) Use turingtest2's generated links with the /content suffix as browser bookmark to the ASC discussions:
Site map of Communities and Categories
https://discussions.apple.com/docs/DOC-2463
6) Adjust the ASC web page layout.
For FireFox
I run with Hiroto's modification to user content. This is the only way these forums are readable for me. How to adjust the format and layout of ASC Web Pages:
https://discussions.apple.com/docs/DOC-7501
For Safari
"ASCPowerTools is a Safari Extension designed to give more control"
http://www.etresoft.com/ascpowertools
7) Read and answer my old posts. I kind of memorize the time I last posted. ( It's way bad that apple eliminated the last poster to a thread. )
8) I use tabbed browsering. From a list of discussions, hold down the command key then click on the link. You get two tabs this way. The original window will keep where you have been.

Design question for database connection in multithreaded socket-server

Dear community,
I am programming a multithreaded socket server. The server creates a new thread for each connection.
The threads and several objects witch are instanced by each thread have to access database-connectivity. Therefore I implemented factory class which administer database connection in a pool. At this point I have a design question.
How should I access the connections from the threads? There are two options:
a) Should I implement in my server class a new method like "getDatabaseConnection" which calls the factory class and returns a pooled connection to the database? In this case each object has to know the server-object and have to call this method in order to get a database connection. That could become very complex as I have to safe a instance of the server object in each object ...
b) Should I develop a static method in my factory class so that each thread could get a database connection by calling the static method of the factory?
Thank you very much for your answer!
Kind regards,
Dak
Message was edited by:
dakger

So your suggestion is to use a static method from a
central class. But those static-methods are not realy
object oriented, are they?There's only one static method, and that's getInstance
If I use singleton pattern, I only create one
instance of the database pooling class in order to
cionfigure it (driver, access data to database and so
on). The threads use than a static method of this
class to get database connection?They use a static method to get the pool instance, getConnection is not static.
Kaj

VOIP Design Question in reference to DHCP

Background:
I have setup VOIP at 3 different remote sites connected via Layer 3 routing and single mode fiber. Each site has it's own voice gateway. I have it setup that the DHCP scopes for data and voice are received from our central data center offsite.
Question:
From a design standpoint, what is best practices in reference where the DHCP server for the voice vlan should be located? i.e. When voice phones request an IP address they are having to go out via Layer 3 and get the address via the DHCP server located off site.
Issue:
If the remote site were to lose power and network connectivity thus losing a way to the DHCP server that is off site. If power were restored without network connectivty the phones will not be able to get an address to be able to reach the local voice gateway.
Thank you for any and all help!
Travis

You can configure your voice gateway with the local DHCP scope, that way DHCP is significant to the local site. This would provide you with DHCP functionality should you loose your WAN connections.
--Matt

SOA real-time design question

Hi All,
We are currently working with SOA Suite 11.1.1.4. I have a SOA application requirement to receive real-time feed for six data tables from an external third party. The implementation consists of five one-way operations in the WSDL to populate the six database tables.
I have a design question. The organization plans to use this data across various departments which requires to replicate or supply the data to other internal databases.
In my understanding there are two options
1) Within the SOA application fork the data hitting the web-service to different databases.
My concern with this approach is what if organizations keep coming with such requests and I keep forking and supplying multiple internal databases with the same data. This feed has to be real-time, too much forking with impact the performance and create unwanted dependencies for this critical link for data supply.2) I could tell other internal projects to get the data from the populated main database.
My concern here is that firstly the data is pushed into this database flat without any constraints and it is difficult to query to get specific data. This design has been purposely put in place to facilitate real-time performance.Also asking every internal projects to get data from main database will affect its performance.
Please suggest which approach should I take (advantage/disadvantage. Apart from the above two solutions, is there any other recommended solution to mitigate the risks. This link between our organization and external party is somewhat like a lifeline for BAU, so certainly don't want to create more dependencies and overhead.
Thanks

I had tried implementing the JMS publisher/subscriber pattern before, unfortunately I experienced performance was not so good compared to the directly writing to the db adapter. I feel the organization SOA infrastructure is not setup correctly to cope with the number of messages coming through from external third party. Our current setup consists of three WebLogic Servers (Admin, SOA, BAM) all running on only 8GB physical RAM on one machine. Is there Oracle guideline for setting up infrastructure for a SOA application receiving roughly 600000 messages a day. I am using SOA 11.1.1.4. JMS publisher/subscriber pattern just does not cope and I see significant performance lag after few hours of running. The JMS server used was WebLogic JMS
Thanks
Edited by: user5108636 on Jun 13, 2011 4:19 PM
Edited by: user5108636 on Jun 13, 2011 7:03 PM

Workflow design questions: FM vs WF to call FM

Hereu2019s a couple of workflow design questions.
1. We have Workitem 123 that allow user to navigate to a custom transaction TX1. User can make changes in TX1. At save or at user command of TX1, the program will call a FM (FM1) to delete WI 123 and create a new WI to send to a different agent.
Since Workitem 123 is still open and lock, the FM1 cannot delete it immediately, it has to use a DO loop to check if the Workitem 123 is dequeued before performing the WI delete.
Alternative: instead of calling the FM1, the program can raise an event which calls a new workflow, which has 1 step/task/new method which call the FM1. Even with this alternative, the Workitem 123 can still be locked when the new workflowu2019s task/method calls the FM1.
I do not like the alternative, which calls the same FM1 indirectly via a new workflow/step/task/method.
2. When an application object changes, the user exit will call a FMx which is related to workflow. The ABAP developer do not want to call the FMx directly, she wants to raise an event which call a workflow .. step .. task .. method .. FMx indirectly. This way any commit that happens in the FMx will not affect the application objectu2019s COMMIT.
My recommendation is to call the FMx using u2018in Update tasku2019 so that the FMx is only called after the COMMIT of the application object.
Any recommendation?
Amy

Mike,
Yes, in my first design, the TX can 1. raise a terminating event for the existing workitem/workflow and then 2. raise another event to call another workflow. Both 1 and 2 will be in FM1.
Then the design question is: Should the FM1 be called from TX directly or should the TX raise an event to call a new workflow which has 1 step/task, which calls a method in the Business object, and the method calls the FM1?
In my second design question, when an application object changes, the user exit will call a FMx which is related to workflow. The ABAP developer do not want to call the FMx directly, she wants to raise an event which call a workflow, which has 1 step/task, which calls a method, which calls the FMx indirectly. This way any commit that happens in the FMx will not affect the application objectu2019s COMMIT.
My recommendation is either call the FMx using u2018in Update tasku2019 so that the FMx is only called after the COMMIT of the application object or raise an event to call a receiver FM (FMx).
Thanks.
Amy

Centralized WLC Design Question

Dears,
In my scenario, i am designing CEntralized WLC deployment. I have 30 AP in Buidling X(200 Users) and 20 AP in Buidling Y(150 Users). I am planning to install HA WLC CLuster where Pimary & Secondary WLC will reside in physically different Data Centers A & B.
I have a wireless Design Question and i am not able to get clear answers. Please refer to the attached drawing and answer the following queries:
If Buidling X users want to talk to building Y Users, then how Control & Data Traffic flow will happen between Buidling X & Y. Would all the traffic will go to Primary WLC from Bldg X APs first and then it will be Re Routed back to Buidling Y APs? Can i achieve direct switching between Bldg X&Y APs without going toward WLC?
If Building X & Y Users want to access the internet, how would be traffic flow? Would the traffic from X&Y AP will go tunnel all the traffic towards WLC and then it will be routed to internet gateway?is it possible for Bldg X&Y AP to directly send traffic towards Internet Gateway without going to controllers?
I have planned to put WLC at physically different locations in different DC A & B. Is it recommended to have such a design? What would be the Failver traffic volume if Primary WLC goes down and secondary controller takes over?
My Reason to go for Centralized deployment is that i want to achieve Centralized Authentication with Local Switching. Please give your recommendations and feedback
Regards,
Rameez

If Buidling X users want to talk to building Y Users, then how Control & Data Traffic flow will happen between Buidling X & Y. Would all the traffic will go to Primary WLC from Bldg X APs first and then it will be Re Routed back to Buidling Y APs? Can i achieve direct switching between Bldg X&Y APs without going toward WLC?
Traffic flows to the WLC that is the primary for the AP's, then its routed over your network.
If Building X & Y Users want to access the Internet, how would be traffic flow? Would the traffic from X&Y AP will go tunnel all the traffic towards WLC and then it will be routed to Internet gateway?is it possible for Bldg X&Y AP to directly send traffic towards Internet Gateway without going to controllers?
The WLC isn't a router, so you would have to put the Internet traffic an a subnet and route.
I have planned to put WLC at physically different locations in different DC A & B. Is it recommended to have such a design? What would be the Failover traffic volume if Primary WLC goes down and secondary controller takes over?
Like I mentioned... earlier, the two HA WLC has to be on the same layer 2 subnet in order for you to use HA. The guide mentions an Ethernet cable to connect both the HA ports on the WLC.
Thanks,
Scott
Help out other by using the rating system and marking answered questions as "Answered"

A question from my textbook.

I read up on a question from my textbook that has wording which confuses me... Here it is from Java Concepts by Cay Horstmann:
"Implement a combination lock class. A combination lock has a dial with 26 positions labeled A....Z. The dial needs to be set three times. If it is set to the correct combination, the lock can be opened. When the lock is closed again, the combination can be entered again. If a user sets the dial more than three times, the last three settings determine whether the lock can be opened. An important part of this exercise is to implement a suitable interface for the CombinationLock class."
Basically, I need to design a program that asks for a combination consisting of three random letters, asks the user to enter the three letters and returns a String according to the combination entered?

TheAlliedCentralAxis wrote:
I read up on a question from my textbook that has wording which confuses me... Here it is from Java Concepts by Cay Horstmann:
"Implement a combination lock class. A combination lock has a dial with 26 positions labeled A....Z. The dial needs to be set three times. If it is set to the correct combination, the lock can be opened. When the lock is closed again, the combination can be entered again. If a user sets the dial more than three times, the last three settings determine whether the lock can be opened. An important part of this exercise is to implement a suitable interface for the CombinationLock class."
Basically, I need to design a program that asks for a combination consisting of three random letters, asks the user to enter the three letters and returns a String according to the combination entered?No. Since the problem emphasized "If a user sets the dial more than three times, the last three settings determine whether the lock can be opened", I think that asking the user for three letters goes against the problem description. Don't you? And the exercise doesn't ask you to design the user interface, does it? It asks you to design Lock.

DB Design Question From A Novice

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