How To Handle Inheritance - Different Type Of Structures
Apr 2, 2014
Every type of controllable object in my game is a type of Entity, and so extends Entity. This is broken down into Ship(s) and Structure(s). But I have different types of structures as well. The problem is that I use an ArrayList<Structure> to store all of a team's structures, but I need to be able to loop through that, and still be able to reference the subclasses of those structures.
For example, I have a JumpGate, which extends Structure. I need to be able to reference a particular JumpGate - as a JumpGate - and not as a Structure. However, the way that I cycle through all of the different types of structures is with an ArrayList<Structure>. I could get around this by having an ArrayList<JumpGate>, however, I would then need a seperate ArrayList for every type of Structure, which would get messy.
Now lets say that I want to access a method 'addInterest()' that is in the 'SavingsAccount' class I would have to do: '((SavingsAccount)s).addInterest();'
The question I have is why do I have to cast 'b' to SavingsAccount? Isn't the actual object reference of 'b' already an instance of 'SavingsAccount' class? How does the 'BankAccount' affect the object itself? I'm really confused as to what class is truly getting instantiated and how BankAccount and SavingsAccount are both functioning to make the object 'b'.
I'm finishing my data structures class and looking for internships and trying to prepare myself for real world application of things I've learned. I'm trying to figure out what sort of project I can start or start over winter break that would use the new data structures I've learned (BSTs, Heaps, Hash Tables, etc). We have been implementing these from scratch but would I be using a library for these on the job? If so, should I implement them that way instead? I have a registrar project from my first data structures class where I used a linked list and then an array list to take care of the different students, classes, and instructors. Maybe I should clean that up and just use that?
how these data structures can be used in non-trivial situations and why I should use one over another. I just don't know a good place to start.
I have one Insert method One traversal method, with a post-order( I don't know if I need to use pre-order, I'm trying to use a very poor hash function ℎ(xx)= √xx xKK mod 2 where xx is 2012559 and KK=3.14. If ℎ(xx) = 0, my traversal method is pre-order, and if ℎ(xx) = 1 my traversal will be post-order.I have 4 separated classes, Tree.java, Node.java, Test.java and traversalType.java
package BST; public class Node { int data; Node leftChild; Node rightChild; public Node(){
query ="Select major_career.Major_Title, career.ISCOTitle,career.FS.... " //only partial, // I swear the query is correct resultSet = statement.executeQuery(query); //this executes it relArr = new ArrayList<String>(); //don't worry it is intialized
In the code below I tried to store the resultset components into the arraylist
int j = 1; while (resultSet.next()) { while(j<=numberOfColumns){ relArr.add(resultSet.getObject(j).toString()); j++; } } // end while
I am not sure whether the arraylist is able to store the result set because when i try to display it like show below it only shows some rows and only the first column
Iterator it = relArr.iterator(); while (it.hasNext()) { System.out.println(it.next());
I want to manipulate the resultset results in my program by copying the resultset values to other datastructures.
I have one Insert method One traversal method, with a post-order( I don't know if I need to use pre-order, I'm trying to use a very poor hash function ℎ(xx)= √xx xKK mod 2 where xx is 2012559 and KK=3.14. If ℎ(xx) = 0, my traversal method is pre-order, and if ℎ(xx) = 1 my traversal will be post-order.
I have 4 separated classes, Tree.java, Node.java, Test.java and traversalType.java
package BST; public class Node { int data; Node leftChild; Node rightChild; public Node(){
In my EJB modules, to prevent that any JPA exception is ever thrown, I check the condition that would cause the exception beforehand. For example, the exception javax.persistence.EntityExistsException is never thrown because, before persisting the entity, I check if such primary key already exists in the DB. Is it the right way to do this?
Another approach is too allow the JPA exceptions to be thrown and catch them in a try-catch block, and then throw my custom exception from the "catch" block. However it requires to call EntityManager.flush () at the end of the "try" block. Otherwise the exception throw could be deferred and never be caught by my block.
So my question is simply about how to best lay out my code so that each classes are talking to each other in the best way possible. I have a habit of creating a "handler" that just holds instances of either class and make them interact such as a player/map handler, that holds an instance of a player & map and then checks things such as collisions, though i'm not sure if this is the best practice. i'm just trying to make sure i'm always laying out my code the best way I can as I tend to get a little messy
I have an ecommerce site that has about 100000 SKUs. What is the best practice for handling all the product images as far as where to store them and how to display them on the pages? Should I have a separate HTTP server to serve the images?
I am trying to execute the a command using process builder. But that command is having some Japanese Character. So it is executing the command but result is not as expected.
command i tried : 1) echo 拝見 マイクロエレクトロニクス 2) mkdir "d: est拝見 マイクロエレクトロニクス" OS: XP SP2
result: some chunk char are getting displayed.
See here a sample code which i tried ...
String commandNotWorksFine ="echo 拝見 マイクロエレクトロニクス"; String charSetname = "Shift_JIS"; String[] envArr = new String[] { "cmd", "/c", commandNotWorksFine}; ProcessBuilder builder = new ProcessBuilder(envArr); Process p = builder.start();
I have come across some code where it attempts to save an entity to a database, but before it does it validates that the name of the entity is unique. If it is not unique it throws a runtime exception. This results in the ugly default exception web page being displayed. Is there any way to propagate this back to the JSF page where the user enters and clicks the form button to save the entity? The page already handles some error cases such as "field required" using the h:inputText's 'required' attribute. Need something more for name validation.
/** * Servlet implementation class InvoicingDeptServlet */ @WebServlet("/InvoicingDeptServlet") public class InvoicingDeptServlet extends HttpServlet { private static final long serialVersionUID = 1L; //Make arraylist global object ArrayList<InvoiceData> invoiceList = new ArrayList<InvoiceData>();
I have a project that is asking me to create a program that will handle a Golfer and his scores. The program will be comprised of three classes: a Golfer class that will manage all the golfer's scores, a Score class and a Tester class to drive the other classes. To accomplish this task the program will use a partially filled array to store the golfer's scores. I have the majority of the code written. It compiles fine, but when I compile and run it only gives the following output.
Tiger ID Number: 1001 Home Course: Pebble Beach Score Date Course Course Rating Course Slope [LScore;@15db9742
I am not sure what I am doing wrong. I have been over and over the code. It is also only printing one golfers information. I have tried creating a for loop for the for the toString in the Golfer class but I am getting the following error Golfer.java:117: error: missing return statement.
I am at a loss here is the code I have for the three sections.
public class Golfer { private String name; private String homeCourse; private int idNum; private Score[] scores; private static int nextIDNum = 1000;
I can't find an handler or a listener to intercept the 'Save as' window that should pops up when i click on a download link in a webview embedded page.
I want to ask if there is an option to set the vertical position of the node handles of the TreeView-control.
I used a custom TreeCell factory with icons of sizes between 24 and 64 pixel and the location of the handle is regardless of the size of the icon on top of the cell. So if you got large icons the view did not look so nice.What I want is a property or something to center the handle in the cell depending on the size of the cell. Is there such an option?
I have a page which lists items using a ui:repeat. The repeat is surrounded by my h:form tag.
Now I have made it so that when click an item, then I load some item details - render them in their own xhtml file and inject the result into the dom tree.
This is causing some problems.
* My injected content has commandButtons and commandLinks which do not work because I don't have a form in my injected page - since this would cause nested forms :-( * tried to replace commandButtons and commandLinks and instead create unique url's that I can call to get my work done - but how to I then re-render a panelGroup on then page? tried using jsf.ajax.request but I'm not able to get part of the page (a shoppingcart) to update
Basic outline
<h:form> <table> <ui:repeat ...> <tr><td onclick="...">Click here to load item details</td></tr><tr><td id="itemDetailPlaceholder"></td></tr> </ui:repeat> </table> </h:form>
Having with LSL and JSF working together? The only thing I have gotten to work with LSL is PHP, and I know I could get JSP working with it with a little research. However, I rather not mix them on my server.
The only requirement for LSL to work with it is there needs be a custom page that can handle get and post request directly. I have not done this with JSF yet so I'm wondering how that would look.
I need to write server side program(Servlet) which must be access by several requests at same time.how to handle this using java? Do i need to use queue or multiple instance of same class. Any example server method which returns the results based on ID
public String getResut(int id){
1)get db connection 2)get the result from db 3) retun the result }
i'd been using Opencsv to upload all this data into my Db(Postgres) using EclipseLink with batch inserting, it wont take more than 5 secs to load 200k+ data cause all the columns are of type string so theres no format require, the problem comes when i need to give a special format to the data that is in this table (date, Integer, etc).
Right now how it works:
- Ill go row by row (when its required) verifying the format of the data and convert it with something like this Ex: Date date = Fechas.strToDate(data, Pattern) and fill the new Object with this info
what i'm planing to do
- With the function of EclipseLink OPERATOR im gonna use that to change all the rows of a column that requires a NUMBER format with OPERATOR('ToNumber',column1,'9999999999')
i cant do the same for Date cause ill get an error if the data doesn't have a Date like pattern
how to handle this Date formatting(from a query, or directly in java).
How to catch the event when table view's column are re-positioned. Basically when the column is re-positioned from 1 position to 5 position , i want to do update the db.
If you have final int i = 1; short s = 1; switch(s) { case i: System.out.println(i); }
it runs fine. Note that the switch expression is of type short (2 bytes) and the case constant is of type int (4 bytes).My question is: Is the type irrelevant as long as the value is within the boundaries of the type of the switch expression?I have the feeling that this is true since:
byte b = 127; final int i = 127; switch(b) { case i: System.out.println(i); }
This runs fine again, but if I change the literal assigned to i to 128, which is out of range for type byte, then the compiler complains.Is it true that in the first example the short variable and in the second example the byte variable (the switch expressions) are first implicitly converted to an int and then compared with the case constants?
