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  • Action listener for JButton array

    - by user530809
    Let's say I have a program with 2D array of buttons, and when you click one of them it turns red. I didn't want to declare every single button seperately so I just created JButton[][] array for them. The problem is that I don't know how to use action listener on any of the buttons in the array so it would change the color of this particular button, and none of related questions is relevant to this. I tried to use "for" but it doesn't help: package appli; import javax.swing.*; import java.awt.*; import java.awt.event.*; public class MainW extends JFrame implements ActionListener { public MainW(){ setSize(640,480); setTitle("title"); setLayout(null); JButton[][] btnz = new JButton[5][5]; for(Integer i=0;i<5;i++) { for(Integer j=0;j<5;j++) { btnz[i][j]= new JButton(""); btnz[i][j].setBackground(Color.WHITE); btnz[i][j].setBounds(10+20*i,10+20*j,20,20); add(btnz[i][j]); btnz[i][j].addActionListener(this); } } setDefaultCloseOperation(EXIT_ON_CLOSE); setVisible(true); } public void actionPerformed(ActionEvent e){ for(Integer i=0;i<5;i++) { for(Integer j=0;j<5;j++) { if (e.getSource()==btnz[i][j]); { btnz[i][j].setBackground(Color.RED); } } } } }

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  • What is a good use case for static import of methods?

    - by Miserable Variable
    Just got a review comment that my static import of the method was not a good idea. The static import was of a method from a DA class, which has mostly static methods. So in middle of the business logic I had a da activity that apparently seemed to belong to the current class: import static some.package.DA.*; class BusinessObject { void someMethod() { .... save(this); } } The reviewer was not keen that I change the code and I didn't but I do kind of agree with him. One reason given for not static-importing was it was confusing where the method was defined, it wasn't in the current class and not in any superclass so it too some time to identify its definition (the web based review system does not have clickable links like IDE :-) I don't really think this matters, static-imports are still quite new and soon we will all get used to locating them. But the other reason, the one I agree with, is that an unqualified method call seems to belong to current object and should not jump contexts. But if it really did belong, it would make sense to extend that super class. So, when does it make sense to static import methods? When have you done it? Did/do you like the way the unqualified calls look? EDIT: The popular opinion seems to be that static-import methods if nobody is going to confuse them as methods of the current class. For example methods from java.lang.Math and java.awt.Color. But if abs and getAlpha are not ambiguous I don't see why readEmployee is. As in lot of programming choices, I think this too is a personal preference thing. Thanks for your response guys, I am closing the question.

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  • Setup for games animation: How do I know JFrame is finished setting itself up?

    - by Jokkel
    I'm using javax.swing.JFrame to draw game animations using double buffer strategy. First, I set up the frame. JFrame frame = new JFrame(); frame.setVisible(true); Now, I draw an object (let it be a circle, doesn't matter) like this. frame.createBufferStrategy(2); bufferStrategy = frame.getBufferStrategy(); Graphics g = bufferStrategy.getDrawGraphics(); circle.draw(g); bufferStrategy.show(); The problem is that the frame is not always fully set-up when the drawing takes place. Seems like JFrame needs up to three steps in resizing itself, until it reaches it's final size. That makes the drawing slide out of frame or hinders it to appear completely from time to time. I already managed to delay things using SwingUtilities.invokeLater(). While this improved the result, there are still times when the drawing slides away / looks prematurely draw. Any idea / strategy? Thanks in advance. EDIT: Ok thanks so far. I didn't mention that I write a little Pong game in the first place. Sorry for the confusion What I actually looked for was the right setup for accelerated game animations done in Java. While reading through the suggestions I found my question answered (though indirectly) here and this example made things clear for me. A resume for this might be that for animating game graphics in Java, the first step is to get rid of the GUI logic overhead.

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  • Question about singleton property

    - by Jack
    I'm reading the java tutorial for enums located here and have a question: http://java.sun.com/j2se/1.5.0/docs/guide/language/enums.html#Card The part i'm confused about is as follows: "The Card class, above, contains a static factory that returns a deck, but there is no way to get an individual card from its rank and suit. Merely exposing the constructor would destroy the singleton property (that only a single instance of each card is allowed to exist). Here is how to write a static factory that preserves the singleton property, using a nested EnumMap: " Now as I understand, changing the original private "Card" constructor to public would allow us to instantiate an unlimited number of copies of a "Card" object with a given suit+rank. The solution as proposed was to create an EnumMap which would store four Maps (one for each suit), which themselves contained 13 Card objects with the rank as their keys. And so now if you wanted to retrieve a specific Card object from the deck, you would just call the "valueOf" method. My question now is, what's the prevent you with calling the valueOf method as many times as you like? Wouldn't that lead to the same problem as making the original private constructor public? Thanks.

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  • String Index Out Of Bound Exception error

    - by Fd Fehfhd
    Im not really sure why a am getting this error. But here is my code it is meant to test palindromes disregarding punctuation. So here is my code import java.util.Scanner; public class PalindromeTester { public static void main(String [] args) { Scanner kb = new Scanner(System.in); String txt = ""; int left; int right; int cntr = 0; do { System.out.println("Enter a word, phrase, or sentence (blank line to stop):"); txt = kb.nextLine(); txt = txt.toLowerCase(); char yP; String noP = ""; for (int i = 0; i < txt.length(); i++) { yP = txt.charAt(i); if (Character.isLetterOrDigit(txt.charAt(yP))) { noP += yP; } } txt = noP; left = 0; right = txt.length() -1; while (txt.charAt(left) == txt.charAt(right) && right > left) { left++; right--; } if (left > right) { System.out.println("Palindrome"); cntr++; } else { System.out.println("Not a palindrome"); } } while (!txt.equals("")); System.out.println("You found " + cntr + " palindromes. Thank you for using palindromeTester."); } } And if i test it and then i put enter so it will tell me how many palindromes you found the error i am getting is javav.lang.StringIndexOutOfBoundException : String index out of range 0 at PalindromeTester.main(PalindromeTester.java:38) and line 28 is while (txt.charAt(left) == txt.charAt(right) && right > left) Thanks for the help in advance

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  • Raspberry Pi broadcast serial port data to local network

    - by D051P0
    I didn't find anything to help me with this problem. What I want is: Serial device sends repeatedly some data to serial port. Raspberry Pi should get this data from RxD and stream it to local network via port 10001 without filtering it. So I can find this device on my pc. This should also work in other direction: Raspberry listen to port 10001 and forward all data from local network to TxD. I'm newbie in Linux World. How can I listen to some port on Raspberry Pi and send broadcast to the same port? I'm using Raspbian Wheezy with soft float. I have found a library Pi4j for Java, that I already use to get and write data from/to serial port. final Serial serial = SerialFactory.createInstance(); serial.addListener(new SerialDataListener() { public void dataReceived(SerialDataEvent event) { forward(event.getData()); } }); event.getData() is a String, which I want to broadcast in my local network. Is it generally a good Idea to use Java for that? I need also a String from port 10001, which I can forward to serial port.

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  • Is there a way to make sure classes implementing an Interface implement static methods?

    - by Tobias Kienzler
    Frist of all, I read erickson's usefull reply to "Why can’t I define a static method in a Java interface?". This question is not about the "why" but about the "how then?". So basically I want one Interface to provide both usual methods and e.g. a getSimilarObject method. For (a made up) example public interface ParametricFunction { /** @return f(x) using the parameters */ static abstract public double getValue(double x, double[] parameters); /** @return The function's name */ static abstract public String getName(); } and then public class Parabola implements ParametricFunction { /** @return f(x) = parameters[0] * x² + parameters[1] * x + parameters[2] */ static public double getValue(double x, double[] parameters) { return ( parameters[2] + x*(parameters[1] + x*parameters[0])); } static public String getName() { return "Parabola"; } } Since this is not allowed in the current Java standard, what is the closest thing to this? The idea behind this is putting several ParametricFunction's in a package and use Reflection to list them all, allowing the user to pick e.g. which one to plot. Obviously one could provide a loader class containing an array of the available ParametricFunction's, but every time a new one is implemented one has to remember adding it there, too.

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  • Detecting TCP dropout over an unreliable network

    - by yx
    I am doing some experimentation over an unreliable radio network (home brewed) using very rudimentary java socket programming to transfer messages back and forth between the end nodes. The setup is as follows: Node A --- Relay Node --- Node B One problem I am constantly running into is that somehow the connection drops out and neither Node A or B knows that the link is dead, and yet continues to transmit data. The TCP connection does not time out either. I have added in a heartbeat message that causes a timeout after a while, but I still would like to know what is the underlying cause of why TCP does not time out. Here are the options I am enabling when setting up a socket: channel.socket().setKeepAlive(false); channel.socket().setTrafficClass(0x08); // for max throughput This behavior is strange since it is totally different than when I have a wired network. On a wired network, I can simulate a disconnected connection by pulling out the ethernet cord, however, once I plug the cord back in, the connection becomes restablished and messages begin to be passed through once more. On the radio network, the connection is never reestablished and once it silently dies, the messages never resume. Is there some other unknown java implentation or setting for a socket that I can use, also, why am I seeing this behavior in the first place? And yes, before anyone says anything, I know TCP is not the preffered choice over an unreliable network, but in this case I wanted to ensure no packet loss.

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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • Calling an Overridden Method from a Parent-Class Constructor

    - by Vaibhav Bajpai
    I tried calling an overridden method from a constructor of a parent class and noticed different behavior across languages. C++ - echoes A.foo() class A{ public: A(){foo();} virtual void foo(){cout<<"A.foo()";} }; class B : public A{ public: B(){} void foo(){cout<<"B.foo()";} }; int main(){ B *b = new B(); } Java - echoes B.foo() class A{ public A(){foo();} public void foo(){System.out.println("A.foo()");} } class B extends A{ public void foo(){System.out.println("B.foo()");} } class Demo{ public static void main(String args[]){ B b = new B(); } } C# - echoes B.foo() class A{ public A(){foo();} public virtual void foo(){Console.WriteLine("A.foo()");} } class B : A{ public override void foo(){Console.WriteLine("B.foo()");} } class MainClass { public static void Main (string[] args) { B b = new B(); } } I realize that in C++ objects are created from top-most parent going down the hierarchy, so when the constructor calls the overridden method, B does not even exist, so it calls the A' version of the method. However, I am not sure why I am getting different behavior in Java and C#.

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  • How to drop/restart a client connection to a flaky socket server

    - by Steve Prior
    I've got Java code which makes requests via sockets from a server written in C++. The communication is simply that the java code writes a line for a request and the server then writes a line in response, but sometimes it seems that the server doesn't respond, so I've implemented an ExecutorService based timeout which tries to drop and restart the connection. To work with the connection I keep: Socket server; PrintWriter out; BufferedReader in; so setting up the connection is a matter of: server = new Socket(hostname, port); out = new PrintWriter(new OutputStreamWriter(server.getOutputStream())); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); If it weren't for the timeout code the request/receive steps are simply: String request="some request"; out.println(request); out.flush(); String response = in.readLine(); When I received a timeout I was trying to close the connection with: in.close(); out.close(); socket.close(); but one of these closes seems to block and never return. Can anyone give me a clue why one of these would block and what would be the proper way to abandon the connection and not end up with resource leak issues?

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  • For each loop not reading in the last item

    - by Gandalf StormCrow
    I'm trying to read in a multi line string then split it then print it .. here is the string : 1T1b5T!1T2b1T1b2T!1T1b1T2b2T!1T3b1T1b1T!3T3b1T!1T3b1T1b1T!5T1*1T 11X21b1X 4X1b1X When I split the string with ! I get this without the last line string : 1T1b5T 1T1b5T1T2b1T1b2T 1T2b1T1b2T1T1b1T2b2T 1T1b1T2b2T1T3b1T1b1T 1T3b1T1b1T3T3b1T 3T3b1T1T3b1T1b1T 1T3b1T1b1T5T1*1T 5T1*1T11X21b1X 11X21b1X Here is my code : import java.io.BufferedInputStream; import java.util.Scanner; public class Main { public static void main(String args[]) { Scanner stdin = new Scanner(new BufferedInputStream(System.in)); while (stdin.hasNext()) { for (String line : stdin.next().split("!")) { System.out.println(line); for (int i = 0; i < line.length(); i++) { System.out.print(line.charAt(i)); } } } } } Where did I make the mistake, why is not reading in the last line? After I read in all lines properly I should go trough each line if I encounter number I should print the next char the n times the number I just read, but that is long way ahead first I need help with this. Thank you

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  • Looking forward to a programming future but confused where to start.

    - by Kraivyne
    Hi there, I am very new to this site and to programming. I started doing some basic programming with python a few weeks ago and recently, messing around with Java basics. My main problem is that I am completely overwhelmed and haven't got the slightest clue where I should be starting. I want to learn programming because I really enjoy doing it, the simple applications that I have managed to conjure up put a smile on my face. My plan is to eventually (by eventually I'm talking about 6 years+) go into games programming. I have been informed that C++ is the best way to go about this but haven't got the slightest clue what book/sight is optimal for someone who is still learning the very basics. These are my questions: I have been to the Definitive C++ Book Guide but am still unsure which book is best to start of with. Should I stick with Python or Java instead of moving on to C++? Is there any advice you would give to a beginner programmer? Thanks again for all your help.

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  • why this code not works?

    - by badgirl
    Hello. I want to create new node of BeanTreeView, and when I add some node in constructor, then run the app, and then I try to view the window with tree, it throws this error java.lang.AssertionError: Component cannot be created for {component=null, displayName=Exploirer, instanceCreate=AlwaysEnabledAction[Exploirer]} at org.openide.windows.OpenComponentAction.getTopComponent(OpenComponentAction.java:71) Why? And how to add node there? See the code. private ProjectsChildren projectsChildren; private ProjectNode projectNode = new ProjectNode(new MainProject("ggg"), projectsChildren); public ExploirerTopComponent() { initComponents(); setName(NbBundle.getMessage(ExploirerTopComponent.class, "CTL_ExploirerTopComponent")); setToolTipText(NbBundle.getMessage(ExploirerTopComponent.class, "HINT_ExploirerTopComponent")); // setIcon(ImageUtilities.loadImage(ICON_PATH, true)); //map.put("delete", ExplorerUtils.actionDelete(mgr, true)); associateLookup (ExplorerUtils.createLookup(mgr, getActionMap())); //projectsChildren.createProject("demence"); /* somewhere here is the problem*/ mgr.setRootContext(projectNode); ProjectNode[] pr = null; pr[0] = projectNode; mgr.getRootContext().getChildren().add(pr); }

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  • Suitable web framework for the following scenario

    - by Paralife
    I have the following scenario: I have a view in an Oracle server and all Iwant is to show that view in a web browser, along with an input field or two for basic filtering. No users, no authentication, just this view maybe with a column or two linking to a second page for master detail viewing. The children are just string descriptions of the columns of the master that contain IDs. No inserts or updates. The question is which is the JAVA based web framework of choice that can accomplish the above in the minimum amount of code lines code time(subjective but also kind of objective if someone has expirience with more than one or two frameworks) configuration effort deployment effort and requirements. dependencies and mem footprint Also: 6. Oracle APEX is not an option. 3,4 and 5 are maybe the same in the sense that they are everything except the functionality coding. I want something that I can compile, deploy by just FTPing to the database host, run and forget. (e.g. For the deployment aspect, Hudson way comes in mind (java -jar hudson.war and that's all)). Also: 3,4 have priority over 1 and 2. (Explanation with a rant: I dont mind coding a lot as long as it is application code and not "why the fuck do we still use javascript over http for everything" code) Thanks.

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  • Quantifying the Performance of Garbage Collection vs. Explicit Memory Management

    - by EmbeddedProg
    I found this article here: Quantifying the Performance of Garbage Collection vs. Explicit Memory Management http://www.cs.umass.edu/~emery/pubs/gcvsmalloc.pdf In the conclusion section, it reads: Comparing runtime, space consumption, and virtual memory footprints over a range of benchmarks, we show that the runtime performance of the best-performing garbage collector is competitive with explicit memory management when given enough memory. In particular, when garbage collection has five times as much memory as required, its runtime performance matches or slightly exceeds that of explicit memory management. However, garbage collection’s performance degrades substantially when it must use smaller heaps. With three times as much memory, it runs 17% slower on average, and with twice as much memory, it runs 70% slower. Garbage collection also is more susceptible to paging when physical memory is scarce. In such conditions, all of the garbage collectors we examine here suffer order-of-magnitude performance penalties relative to explicit memory management. So, if my understanding is correct: if I have an app written in native C++ requiring 100 MB of memory, to achieve the same performance with a "managed" (i.e. garbage collector based) language (e.g. Java, C#), the app should require 5*100 MB = 500 MB? (And with 2*100 MB = 200 MB, the managed app would run 70% slower than the native app?) Do you know if current (i.e. latest Java VM's and .NET 4.0's) garbage collectors suffer the same problems described in the aforementioned article? Has the performance of modern garbage collectors improved? Thanks.

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  • Experiences wanted: producing a jar artifact in IntelliJ

    - by skiaddict1
    Developing with IntelliJ 9.0.2 Community Edition, on the Mac. This is a follow-up to this post about including jar files in an artifact, which has not received any replies. I'm hoping that the reason is that somehow, in creating my artifact (or setting my project settings), I unwittingly did something which people don't tend to do, and which is causing my problem, and that by asking people here to share how they create jar artifacts and set up projects, I will discover what it is. To recap: I have a Java project which depends on two library files. I need to package up the entire thing, with the jars inlined (such that on doing jar -tfv <filename> I see ALL the classes listed, including the ones in the two libraries), into a single jar file. I can make an artifact, I can add the library files to the Output Layout pane, but I CANNOT, no matter what I do, I cannot get the "Inline Artifact" item in the context menu to be selectable (i.e. non-grey) when I right-click on one or other library file. The thing is, making a jar which contains library files as well as the project code is NOT an unusual situation in the Java world! So I figure there are lots of IntelliJ folks out there who have done what I need to do. And I would really like to hear from you folks. What project settings do you use? (be specific, please :-) And exactly how do you set up your jar artifacts? (again, as many specific details as possible, please :-) Clearly, I'd be particularly interested to hear from folks with similar setups to mine (above) who are successfully doing what I need to do. Grateful thanks in advance, folks.

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  • Selenium - Wait for network traffic

    - by Joel
    We're using Selenium with the Java API and some Javascript user extensions. We use a lot of AJAX calls in our app. A lot of our tests fail randomly because sometimes the AJAX calls finish slower than other times so the page isn't fully loaded. We fix that by waiting for specific elements or Thread.sleep. I was trying to find a way to instead just wait for the network traffic to finish. So that we could do this: selenium.click("some JS button"); selenium.waitForNetwork(); assertTrue(something); That way we can get rid of the thread sleep and have tests pass faster when the server responds faster and not have so many tests fail due to timing issues. I haven't been able to find a way to do this searching Google. Does anyone have any ideas how we can accomplish this? (Preferably either through Javascript or the Java API but all suggestions are welcome). Note: the other variations of "waitFor" are not what I'm looking for. We're already using those in clicks and other things. I'm looking for something that waits for the NETWORK TRAFFIC. Thanks for all the feedback, I'll be trying out a couple of the suggestions, but I'm still open to other ideas. Thanks.

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  • Hibernate not loading associated object

    - by Noor
    Hi, i am trying to load a hibernate object ForumMessage but in it contain another object Users and the Users object is not being loaded. My ForumMessage Mapping File: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jan 4, 2011 10:10:29 AM by Hibernate Tools 3.4.0.Beta1 --> <hibernate-mapping> <class name="com.BiddingSystem.Models.ForumMessage" table="FORUMMESSAGE"> <id name="ForumMessageId" type="long"> <column name="FORUMMESSAGEID" /> <generator class="native" /> </id> <property name="ForumMessage" type="java.lang.String"> <column name="FORUMMESSAGE" /> </property> <many-to-one name="User" class="com.BiddingSystem.Models.Users" fetch="join"> <column name="UserId" /> </many-to-one> <property name="DatePosted" type="java.util.Date"> <column name="DATEPOSTED" /> </property> <many-to-one name="Topic" class="com.BiddingSystem.Models.ForumTopic" fetch="join"> <column name="TopicId" /> </many-to-one> </class> </hibernate-mapping> and I am using the follwing code: Session session = gileadHibernateUtil.getSessionFactory().openSession(); SQL="from ForumMessage"; System.out.println(SQL); Query query=session.createQuery(SQL); System.out.println(query.list().size()); return new LinkedList <ForumMessage>(query.list());

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  • Using enum values to represent binary operators (or functions)

    - by Bears will eat you
    I'm looking for an elegant way to use values in a Java enum to represent operations or functions. My guess is, since this is Java, there just isn't going to be a nice way to do it, but here goes anyway. My enum looks something like this: public enum Operator { LT, LTEQ, EQEQ, GT, GTEQ, NEQ; ... } where LT means < (less than), LTEQ means <= (less than or equal to), etc - you get the idea. Now I want to actually use these enum values to apply an operator. I know I could do this just using a whole bunch of if-statements, but that's the ugly, OO way, e.g.: int a = ..., b = ...; Operator foo = ...; // one of the enum values if (foo == Operator.LT) { return a < b; } else if (foo == Operator.LTEQ) { return a <= b; } else if ... // etc What I'd like to be able to do is cut out this structure and use some sort of first-class function or even polymorphism, but I'm not really sure how. Something like: int a = ..., b = ...; Operator foo = ...; return foo.apply(a, b); or even int a = ..., b = ...; Operator foo = ...; return a foo.convertToOperator() b; But as far as I've seen, I don't think it's possible to return an operator or function (at least, not without using some 3rd-party library). Any suggestions?

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  • Extending abstract classes in c#

    - by ng
    I am a Java developer and I have noticed some differences in extending abstract classes in c# as opposed to Java. I was wondering how a c# developer would achived the following. 1) Covarience public abstract class A { public abstract List<B> List(); } public class BList : List<T> where T : B { } public abstract class C : A { public abstract BList List(); } So in the above hierarchy, there is covarience in C where it returns a type compatible with what A returns. However this gives me an error in Visual Studio. Is there a way to specify a covarient return type in c#? 2) Adding a setter to a property public abstract class A { public abstract String Name { get; } } public abstract class B : A { public abstract String Name { get; set } } Here the compiler complains of hiding. Any suggestions? Please do not suggest using interfaces unless that is the ONLY way to do this.

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  • How to improve my software project's speed?

    - by Blitzkr1eg
    I'm doing a school software project with my class mates in Java. We store the info on a remote db. When we start the application we pull all the information from the database and transform it into objects to use in our application (using java sql statemens). In the application we edit some of these objects and then when we exit the application we save or update information in the database using Hibernate. As you see we dont use Hibernate for pulling in information, we use it just for saving and updating. We have 2, but very similar problems. The loading of object(when we start the app) and the saving of objects(with Hibernate) in the db(when closing the app) is taking too much time. And our project its not a huge enterprise application, its a quite small app, we just manage some students, teachers, homeworks and tests. So our db is also very very small. How could we increase performance ? later edit: if we use a local database it runs very quick, it just runs slow on remote databases

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  • public String shorthand(String in)

    - by luvthug
    Hi All, I am stuck on this code. The code should use the class StringBuilder to build an output string by appending non-vowel characters from its argument in to the result it returns. It needs to identify vowels to be removed using the helper metod i created which is public boolean isVowel(char c). public String shorthand(String in) this is the method I need help with. I have created the stringbuilder but the if condition does not accept isVowel method. import java.io.*; import java.util.*; public class Shorthand { public boolean isVowel(char c) { if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u' || c == 'A'|| c == 'E'||c == 'I'|| c == 'O'|| c == 'U') { return true; } else { return false; } } //TODO Complete the shorthand method public String shorthand(String in) //this is the code I need help with { StringBuilder vowel = new StringBuilder(); if (isVowel() == false)strong text { vowel.append(in); } return vowel.toString(); } //TODO Complete the run method public void run() throws IOException { String yourLine; Scanner sc = new Scanner(System.in); yourLine = sc.nextLine(); while(!yourLine.equals("*")); { System.out.println("Enter your line of text"); } yourLine = sc.nextLine(); } }

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  • Identify words with ascending characters from text file

    - by user2914000
    I am having a fair amount of trouble trying to write a program that counts the amount of ascending words (words in which each character is larger than the previous character) in a text file. I have tried a few different methods to solve this but cannot seem to get it working. If anyone could help me revise the code to work properly it would be appreciated. The code will print about 5 of the words from the list of nearly 20000, but none considered are ascending (the file does have many ascending words) and it sometimes prints the same word twice. I am printing theWord to the console simply to see if the code works. import java.util.Scanner; import java.io.*; public class { public static void main (String [] args) throws FileNotFoundException{ String theWord; Scanner inputFile = new Scanner(new File("file.txt")); boolean ascending = true; int i = 1; while(inputFile.hasNextLine()){ theWord = inputFile.nextLine(); if(theWord.length() >= 2){ while(i < theWord.length() - 1){ if(theWord.charAt(i) <= theWord.charAt(i + 1)){ ascending = true; System.out.println("+ " + theWord); totalNum = totalNum + 1; } else{ ascending = false; System.out.println("= " + theWord); } i++; } } }

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  • Multiple Rectangle Generation

    - by user1610541
    In my code i wrote a method that creates a rectangle at mouseX, mouseY. but all it does is update the position of that rectangle so it follows the mouse, i want it to create a new one at the mouse every time the method runs, can someone please help? this is my method public void drawParticle(float x, float y){ g.drawRect(x, y, 4, 4); } The main class Control call the drawParticle method; import java.awt.Point; import java.awt.geom.Point2D; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.SlickException; import org.newdawn.slick.state.BasicGameState; import org.newdawn.slick.state.StateBasedGame; public class Control extends BasicGameState { public static final int ID = 1; public Methods m = new Methods(); public Graphics g = new Graphics(); int mouseX; int mouseY; public void init(GameContainer container, StateBasedGame game) throws SlickException{ } public void render(GameContainer container, StateBasedGame game, Graphics g) throws SlickException { m.drawParticle(mouseX, mouseY); } public void update(GameContainer container, StateBasedGame game, int delta) { } public void mousePressed(int button, int x, int y) { mouseX = x; mouseY = y; } public int getID() { return ID; } } Thanks - Shamus

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