AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Using arrays of objects ?          AppletTalk.com Forum Index -> comp.lang.java View previous topic :: View next topic   Author Message TonyB Guest Posted: Sat Feb 24, 2007 3:38 am    Post subject: Using arrays of objects ? I'm new to java, and would like some advice on how to keep track of groups of objects where the number of objects is not predefined. For example say I have a toolbox class which contains an arbitrary number of tool objects. I want to have a method to add a tool to the toolbox object, and other methods to list the current contents of the toolbox for example. I could keep a reference to each tool object as added in an array of type tool but an array is declared with a fixed length, so short of defining the array to have a some arbitrary large size I can't see how to deal with this list of objects. I don't want to use a database at this time. Is there a better way to do this ? Tony Back to top Casey Hawthorne Guest Posted: Sat Feb 24, 2007 3:48 am    Post subject: Re: Using arrays of objects ? Read up on collection classes and post to comp.lang.java.help -- Regards, Casey Back to top Mark Rafn Guest Posted: Sat Feb 24, 2007 4:30 am    Post subject: Re: Using arrays of objects ? TonyB <tonyb (AT) kerrisway (DOT) freeserve.co.uk> wrote: Quote: I'm new to java, and would like some advice on how to keep track of groups of objects where the number of objects is not predefined. java.util.Collection and friends make this pretty easy. Quote: I could keep a reference to each tool object as added in an array of type tool but an array is declared with a fixed length, so short of defining the array to have a some arbitrary large size I can't see how to deal with this list of objects. I don't want to use a database at this time. ArrayList<Tool> is the most common way to do this. Depending on your needs, you may prefer a HashSet, TreeSet, LinkedList, or some other Collection that fits your performance and usage requirements. -- Mark Rafn dagon (AT) dagon (DOT) net <http://www.dagon.net/> Back to top Joanna Guest Posted: Sun Feb 25, 2007 8:10 am    Post subject: Re: Using arrays of objects ? "TonyB" <tonyb (AT) kerrisway (DOT) freeserve.co.uk> wrote in message news:E9JDh.87996$tQ1.64679 (AT) fe04 (DOT) news.easynews.com... Quote: I'm new to java, and would like some advice on how to keep track of groups of objects where the number of objects is not predefined. For example say I have a toolbox class which contains an arbitrary number of tool objects. I want to have a method to add a tool to the toolbox object, and other methods to list the current contents of the toolbox for example. I could keep a reference to each tool object as added in an array of type tool but an array is declared with a fixed length, so short of defining the array to have a some arbitrary large size I can't see how to deal with this list of objects. I don't want to use a database at this time. Is there a better way to do this ? Tony here we go http://cs.gettysburg.edu/~cpresser/java/ForLoopTest.html Joanna Back to top j1mb0jay Guest Posted: Thu Mar 01, 2007 11:19 pm    Post subject: Re: Using arrays of objects ? TonyB wrote: Quote: I'm new to java, and would like some advice on how to keep track of groups of objects where the number of objects is not predefined. For example say I have a toolbox class which contains an arbitrary number of tool objects. I want to have a method to add a tool to the toolbox object, and other methods to list the current contents of the toolbox for example. I could keep a reference to each tool object as added in an array of type tool but an array is declared with a fixed length, so short of defining the array to have a some arbitrary large size I can't see how to deal with this list of objects. I don't want to use a database at this time. Is there a better way to do this ? Tony ArrayLists would seem to the answer for what you are looking for. http://java.sun.com/j2se/1.4.2/docs/api/java/util/ArrayList.html There is a Iterator class for going through each of the objects in a array, try not to store objects in an array, try to type them first (looking into Interfaces). http://java.sun.com/j2se/1.4.2/docs/api/java/util/Iterator.html http://java.sun.com/docs/books/tutorial/java/concepts/interface.html -- Regards JJ (UWA) Back to top TideRider Guest Posted: Sat Apr 14, 2007 7:50 pm    Post subject: Re: Using arrays of objects ? I would probably use an ArrayList (from java.util). I would also define either an interface or base class for Tool, from which all of the tools are derived, and (using Java 5 or higher) parameterize the ArrayList: ArrayList<Tool> toolbox = new ArrayList<Tool>(); To operate on Tool in the toolbox (again, with Java 5 or higher), you can use: for (Tool tool : toolbox) { //tool variable contains the current tool } -- TideRider "TonyB" <tonyb (AT) kerrisway (DOT) freeserve.co.uk> wrote in message news:E9JDh.87996$tQ1.64679 (AT) fe04 (DOT) news.easynews.com... | I'm new to java, and would like some advice on how to keep track of groups | of objects where the number of objects is not predefined. | For example say I have a toolbox class which contains an arbitrary number of | tool objects. I want to have a method to add a tool to the toolbox object, | and other methods to list the current contents of the toolbox for example. | I could keep a reference to each tool object as added in an array of type | tool but an array is declared with a fixed length, so short of defining the | array to have a some arbitrary large size I can't see how to deal with this | list of objects. I don't want to use a database at this time. | Is there a better way to do this ? | Tony | | Back to top Lew Guest Posted: Sat Apr 14, 2007 8:12 pm    Post subject: Re: Using arrays of objects ? TideRider wrote: Quote: I would probably use ... Just so you know, many newsreaders, mine included, clip material that follows your sig in the reply, and display it "dimmed" or gray in the initial reading. This happened with your replies, which were top-posted. Top-posting also disrupts the flow of the message and makes it harder to read. Please don't top-post. As to your suggestion to use Quote: ArrayList<Tool> toolbox = new ArrayList<Tool>(); It'd likely be better to use List<Tool> toolbox = ... or even Collection<Tool> toolbox = ... For example, if a given Tool should appear only once in 'toolbox', then the implementing class might better be a Set<Tool>. -- Lew Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> comp.lang.java All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.