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  • As a C# developer, would you learn Java to develop for Android or use MonoDroid instead?

    - by Dan Tao
    I'd consider myself pretty well versed in C#. It's my language of choice at the moment, and it's where basically all my professional experience lies. Still, I'm puzzled by the existence of the MonoDroid project. My understanding has always been that C# and Java are very close. Like, if you know one, you can learn the other really quickly. So, as I've considered developing my first Android app, I just assumed I would familiarize myself with Java enough to get started and then just sort of learn as I go. Wouldn't this make more sense than using MonoDroid, which is likely to be less feature-rich than the Java Android SDK, and requires learning its own API (albeit a .NET API) anyway? I just feel like it would be better to learn a new language (and an extremely popular one at that) and get some experience in it—when it's so close to what you already know anyway—rather than stick with a technology you're experienced with, without gaining any more valuable skills. Maybe I'm grossly misrepresenting the average potential MonoDroid user. Maybe it's more for people who are experienced in Java and .NET and just prefer .NET. Or maybe (in fact it's likely) there are other factors I just haven't considered. I'm just wondering, why would you use MonoDroid instead of just developing for Android using Java?

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  • Why is design by contract considered an alternative to the pseudo programming process?

    - by zoopp
    Right now I'm reading Code Complete by Steve McConnell and in chapter 9 he talks about the Pseudo Programming Process (PPP). From what I've understood, the PPP is a way of programming in which the programmer first writes the pseudo code for the routine he's working on, then refines it up to the point where pretty much each pseudo code line can be implemented in 1-3 lines of code, then writes the code in the designated programming language and finally the pseudo code is saved as comments for the purpose of documenting the routine. In chapter 9.4 the author mentions alternatives to the PPP, one of which is 'design by contract'. In design by contract you basically assert preconditions and postconditions of each routine. Now why would that be considered an alternative? To me it seems obvious that I should use both techniques at the same time and not chose one over the other.

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  • Passing data between android ListActivities in Java

    - by Will Janes
    I am new to Android! I am having a problem getting this code to work... Basically I Go from one list activity to another and pass the text from a list item through the intent of the activity to the new list view, then retrieve that text in the new list activity and then preform a http request based on value of that list item. Log Cat 04-05 17:47:32.370: E/AndroidRuntime(30135): FATAL EXCEPTION: main 04-05 17:47:32.370: E/AndroidRuntime(30135): java.lang.ClassCastException:android.widget.LinearLayout 04-05 17:47:32.370: E/AndroidRuntime(30135): at com.thickcrustdesigns.ufood.CatogPage$1.onItemClick(CatogPage.java:66) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.AdapterView.performItemClick(AdapterView.java:284) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.ListView.performItemClick(ListView.java:3731) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1959) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Handler.handleCallback(Handler.java:587) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Handler.dispatchMessage(Handler.java:92) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Looper.loop(Looper.java:130) 04-05 17:47:32.370: E/AndroidRuntime(30135): at android.app.ActivityThread.main(ActivityThread.java:3691) 04-05 17:47:32.370: E/AndroidRuntime(30135): at java.lang.reflect.Method.invokeNative(Native Method) 04-05 17:47:32.370: E/AndroidRuntime(30135): at java.lang.reflect.Method.invoke(Method.java:507) 04-05 17:47:32.370: E/AndroidRuntime(30135): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907) 04-05 17:47:32.370: E/AndroidRuntime(30135): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665) 04-05 17:47:32.370: E/AndroidRuntime(30135): at dalvik.system.NativeStart.main(Native Method) ListActivity 1 package com.thickcrustdesigns.ufood; import java.util.ArrayList; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONException; import org.json.JSONObject; import android.app.ListActivity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.Button; import android.widget.ListView; import android.widget.TextView; public class CatogPage extends ListActivity { ListView listView1; Button btn_bk; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.definition_main); btn_bk = (Button) findViewById(R.id.btn_bk); listView1 = (ListView) findViewById(android.R.id.list); ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>(); nvp.add(new BasicNameValuePair("request", "categories")); ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp); String[] defs = new String[jsondefs.size()]; for (int i = 0; i < jsondefs.size(); i++) { try { defs[i] = jsondefs.get(i).getString("Name"); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } } uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list, defs); listView1.setAdapter(adapter); ListView lv = getListView(); lv.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { TextView tv = (TextView) view; String p = tv.getText().toString(); Intent i = new Intent(getApplicationContext(), Results.class); i.putExtra("category", p); startActivity(i); } }); btn_bk.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { Intent i = new Intent(getApplicationContext(), UFoodAppActivity.class); startActivity(i); } }); } } **ListActivity 2** package com.thickcrustdesigns.ufood; import java.util.ArrayList; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONException; import org.json.JSONObject; import android.app.ListActivity; import android.os.Bundle; import android.widget.ListView; public class Results extends ListActivity { ListView listView1; enum Category { Chicken, Beef, Chinese, Cocktails, Curry, Deserts, Fish, ForOne { public String toString() { return "For One"; } }, Lamb, LightBites { public String toString() { return "Light Bites"; } }, Pasta, Pork, Vegetarian } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.definition_main); listView1 = (ListView) findViewById(android.R.id.list); Bundle data = getIntent().getExtras(); String category = data.getString("category"); Category cat = Category.valueOf(category); String value = null; switch (cat) { case Chicken: value = "Chicken"; break; case Beef: value = "Beef"; break; case Chinese: value = "Chinese"; break; case Cocktails: value = "Cocktails"; break; case Curry: value = "Curry"; break; case Deserts: value = "Deserts"; break; case Fish: value = "Fish"; break; case ForOne: value = "ForOne"; break; case Lamb: value = "Lamb"; break; case LightBites: value = "LightBites"; break; case Pasta: value = "Pasta"; break; case Pork: value = "Pork"; break; case Vegetarian: value = "Vegetarian"; } ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>(); nvp.add(new BasicNameValuePair("request", "category")); nvp.add(new BasicNameValuePair("cat", value)); ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp); String[] defs = new String[jsondefs.size()]; for (int i = 0; i < jsondefs.size(); i++) { try { defs[i] = jsondefs.get(i).getString("Name"); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } } uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list, defs); listView1.setAdapter(adapter); } } Request package com.thickcrustdesigns.ufood; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONArray; import org.json.JSONObject; import android.content.Context; import android.util.Log; import android.widget.Toast; public class Request { @SuppressWarnings("null") public static ArrayList<JSONObject> fetchData(Context context, ArrayList<NameValuePair> nvp) { ArrayList<JSONObject> listItems = new ArrayList<JSONObject>(); InputStream is = null; try { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost( "http://co350-11d.projects02.glos.ac.uk/php/database.php"); httppost.setEntity(new UrlEncodedFormEntity(nvp)); HttpResponse response = httpclient.execute(httppost); HttpEntity entity = response.getEntity(); is = entity.getContent(); } catch (Exception e) { Log.e("log_tag", "Error in http connection" + e.toString()); } // convert response to string String result = ""; try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); InputStream stream = null; StringBuilder sb = null; while ((result = reader.readLine()) != null) { sb.append(result + "\n"); } stream.close(); result = sb.toString(); } catch (Exception e) { Log.e("log_tag", "Error converting result " + e.toString()); } try { JSONArray jArray = new JSONArray(result); for (int i = 0; i < jArray.length(); i++) { JSONObject jo = jArray.getJSONObject(i); listItems.add(jo); } } catch (Exception e) { Toast.makeText(context.getApplicationContext(), "None Found!", Toast.LENGTH_LONG).show(); } return listItems; } } Any help would be grateful! Many Thanks EDIT Sorry very tired so missed out my 2nd ListActivity package com.thickcrustdesigns.ufood; import java.util.ArrayList; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONException; import org.json.JSONObject; import android.app.ListActivity; import android.os.Bundle; import android.widget.ListView; public class Results extends ListActivity { ListView listView1; enum Category { Chicken, Beef, Chinese, Cocktails, Curry, Deserts, Fish, ForOne { public String toString() { return "For One"; } }, Lamb, LightBites { public String toString() { return "Light Bites"; } }, Pasta, Pork, Vegetarian } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.definition_main); listView1 = (ListView) findViewById(android.R.id.list); Bundle data = getIntent().getExtras(); String category = data.getString("category"); Category cat = Category.valueOf(category); String value = null; switch (cat) { case Chicken: value = "Chicken"; break; case Beef: value = "Beef"; break; case Chinese: value = "Chinese"; break; case Cocktails: value = "Cocktails"; break; case Curry: value = "Curry"; break; case Deserts: value = "Deserts"; break; case Fish: value = "Fish"; break; case ForOne: value = "ForOne"; break; case Lamb: value = "Lamb"; break; case LightBites: value = "LightBites"; break; case Pasta: value = "Pasta"; break; case Pork: value = "Pork"; break; case Vegetarian: value = "Vegetarian"; } ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>(); nvp.add(new BasicNameValuePair("request", "category")); nvp.add(new BasicNameValuePair("cat", value)); ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp); String[] defs = new String[jsondefs.size()]; for (int i = 0; i < jsondefs.size(); i++) { try { defs[i] = jsondefs.get(i).getString("Name"); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } } uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list, defs); listView1.setAdapter(adapter); } } Sorry again! Cheers guys!

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  • Which design better when use foreign key instead of a string to store a list of id

    - by Kien Thanh
    I'm building online examination system. I have designed to table, Question and GeneralExam. The table GeneralExam contains info about the exam like name, description, duration,... Now I would like to design table GeneralQuestion, it will contain the ids of questions belongs to a general exam. Currently, I have two ideas to design GeneralQuestion table: It will have two columns: general_exam_id, question_id. It will have two columns: general_exam_id, list_question_ids (string/text). I would like to know which designing is better, or pros and cons of each designing. I'm using Postgresql database.

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  • Generate JFreeChart in servlet

    - by San4o
    I'm trying to generate graphs using JFreeChart. I added record in web.xml, installed jfreechart library. Compiled servlet. Below code of servlet has shown: import java.io.IOException; import java.io.OutputStream; import java.io.File; import javax.servlet.*; import javax.servlet.http.*; import java.awt.Color; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartUtilities; import org.jfree.chart.JFreeChart; import org.jfree.data.general.DefaultPieDataset; public class diagram extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doTestPieChart(request,response); } protected void doTestPieChart(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { OutputStream out = response.getOutputStream(); try { DefaultPieDataset dataset = new DefaultPieDataset(); dataset.setValue("Graphic Novels", 192); dataset.setValue("History", 125); dataset.setValue("Military Fiction", 236); dataset.setValue("Mystery", 547); dataset.setValue("Performing Arts", 210); dataset.setValue("Science, Non-Fiction", 70); dataset.setValue("Science Fiction", 989); JFreeChart chart = ChartFactory.createPieChart( "Books by Type", dataset, true, false, false ); chart.setBackgroundPaint(Color.white); response.setContentType("image/png"); ChartUtilities.writeChartAsPNG(out, chart, 400, 300); /* ServletContext sc = getServletContext(); String filename = sc.getRealPath("pie.png"); File file = new File(filename); ChartUtilities.saveChartAsPNG(file,chart,400,300); */ } catch (Exception e) { System.out.println(e.toString()); } finally { out.close(); } } } When i launch the servlet, mistake has shown : HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Error instantiating servlet class diagram org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.ClassNotFoundException: org.jfree.data.general.PieDataset org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1484) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1329) java.lang.ClassLoader.loadClassInternal(ClassLoader.java:316) java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) note The full stack trace of the root cause is available in the Apache Tomcat/6.0.24 logs. Help me to solve a problem. and where is problem?

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  • What should be the minimal design/scope documentation before development begins?

    - by Oliver Hyde
    I am a junior developer working on my own in the programming aspect of projects. I am given a png file with 5-6 of the pages designed, most times in specific detail. From this I'm asked to develop the back end system needed to maintain the website, usually a cataloging system with products, tags and categories and match the front end to the design. I find myself in a pickle because when I make decisions based on assumptions about the flow of the website, due to a lack of outlining details, I get corrected and am required to rewrite the code to suit what was actually desired. This process happens multiple times throughout a project, often times on the same detail, until it's finally finished, with broken windows all through it. I understand that projects have scope creep, and can appreciate that I need to plan for this, but I feel that in this situation, I'm not receiving enough outlining details to effectively plan for the project, resulting in broken code and a stressed mind. What should be the minimal design/scope documentation I receive before I begin development?

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  • Can't find openjdk's jre? No Java plugin in Chrome web browser.

    - by Patryk
    I have recently installed openjdk just to try out writing some java application $ dpkg -l | grep jdk ii openjdk-7-jdk 7u7-2.3.2a-0ubuntu0.12.04.1 OpenJDK Development Kit (JDK) ii openjdk-7-jre 7u7-2.3.2a-0ubuntu0.12.04.1 OpenJDK Java runtime, using Hotspot JIT ii openjdk-7-jre-headless 7u7-2.3.2a-0ubuntu0.12.04.1 OpenJDK Java runtime, using Hotspot JIT (headless) ii openjdk-7-jre-lib 7u7-2.3.2a-0ubuntu0.12.04.1 OpenJDK Java runtime (architecture independent libraries) That's what I have on my system. Although I have all this installed when in Chrome I go to a website which needs jre it can't find it. How can I fix it ?

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  • JavaFX FXML communication between Application and Controller classes

    - by likethesky
    I am trying to get and destroy an external process I've created via ProcessBuilder in my FXML application close, but it's not working. This is based on the helpful advice Sergey Grinev gave me here. I have tried running with/without the "// myController.setApp(this);" and with "// super.stop();" at top of subclass and at bottom (see commented out/in for that line in MyApp), but no combination works. This probably isn't related to FXML or JavaFX, though I imagine this is a common pattern for developing apps on JavaFX. I suppose I'm asking for a Java best practice for closing dependent processes in a UI-based app like this one (in this case: FXML / JavaFX based), where there is a controller class and an application class. Can you explain what I'm doing wrong? Or better: advise what I should be doing instead? Thanks. In my Application I do this: public class MyApp extends Application { @Override public void start(Stage primaryStage) throws Exception { FXMLLoader fxmlLoader = new FXMLLoader(); Scene scene = (Scene)FXMLLoader.load(getClass().getResource("MyApp.fxml")); MyAppController myController = (MyAppController)fxmlLoader.getController(); primaryStage.setScene(scene); primaryStage.show(); // myController.setApp(this); } @Override public void stop() throws Exception { // super.stop(); // this is called on fx app close, you may call it in an action handler too if (MyAppController.getScriptProcess() != null) { MyAppController.getScriptProcess().destroy(); } super.stop(); } public static void main(String[] args) { launch(args); } } In my Controller I do this: public class MyAppController implements Initializable { private Application app; private static Process scriptProcess; public void setApp(Application a) { app = a; } public static Process getScriptProcess() { return scriptProcess; } } The result when I run with the "commented-out setApp()" not commented out (that is, left in the start method), is the following, immediately upon launch (the main Scene flashes, then disappears, then this dialog appears: "JavaFX Launcher Error: Exception while running Application" And it gives an, "Exception in Application start method" in the console as well. The result when I leave out the "commented-out code" in my MyApp above (that is, remove the "setApp()" from the start method), is that my app does indeed close, but gives this error when it closes: Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1440) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170) at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28) at javafx.event.Event.fireEvent(Event.java:171) at javafx.scene.Node.fireEvent(Node.java:6863) at javafx.scene.control.Button.fire(Button.java:179) at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193) at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336) at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170) at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33) at javafx.event.Event.fireEvent(Event.java:171) at javafx.scene.Scene$MouseHandler.process(Scene.java:3324) at javafx.scene.Scene$MouseHandler.process(Scene.java:3164) at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3119) at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1559) at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2261) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:228) at com.sun.glass.ui.View.handleMouseEvent(View.java:528) at com.sun.glass.ui.View.notifyMouse(View.java:922) at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) at com.sun.glass.ui.gtk.GtkApplication$3$1.run(GtkApplication.java:82) at java.lang.Thread.run(Thread.java:722) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1435) ... 44 more Caused by: java.lang.NullPointerException at mypackage.MyController.handleCancel(MyController.java:300) ... 49 more Clean up...

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  • Design pattern question: encapsulation or inheritance

    - by Matt
    Hey all, I have a question I have been toiling over for quite a while. I am building a templating engine with two main classes Template.php and Tag.php, with a bunch of extension classes like Img.php and String.php. The program works like this: A Template object creates a Tag objects. Each tag object determines which extension class (img, string, etc.) to implement. The point of the Tag class is to provide helper functions for each extension class such as wrap('div'), addClass('slideshow'), etc. Each Img or String class is used to render code specific to what is required, so $Img->render() would give something like <img src='blah.jpg' /> My Question is: Should I encapsulate all extension functionality within the Tag object like so: Tag.php function __construct($namespace, $args) { // Sort out namespace to determine which extension to call $this->extension = new $namespace($this); // Pass in Tag object so it can be used within extension return $this; // Tag object } function render() { return $this->extension->render(); } Img.php function __construct(Tag $T) { $args = $T->getArgs(); $T->addClass('img'); } function render() { return '<img src="blah.jpg" />'; } Usage: $T = new Tag("img", array(...); $T->render(); .... or should I create more of an inheritance structure because "Img is a Tag" Tag.php public static create($namespace, $args) { // Sort out namespace to determine which extension to call return new $namespace($args); } Img.php class Img extends Tag { function __construct($args) { // Determine namespace then call create tag $T = parent::__construct($namespace, $args); } function render() { return '<img src="blah.jpg" />'; } } Usage: $Img = Tag::create('img', array(...)); $Img->render(); One thing I do need is a common interface for creating custom tags, ie I can instantiate Img(...) then instantiate String(...), I do need to instantiate each extension using Tag. I know this is somewhat vague of a question, I'm hoping some of you have dealt with this in the past and can foresee certain issues with choosing each design pattern. If you have any other suggestions I would love to hear them. Thanks! Matt Mueller

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  • What benefits does a game design degree have for a hobby game programmer?

    - by sm4
    I am interested in studying game design, not because I want a job in the games industry, but because I am interested in the subject itself. I read the following questions, but they mostly deal with the effects on your career in game industry. Should I consider a graduate degree in game development? Game Development Degree vs Computer Science Degree First I thought a game development degree could be beneficial. But from the websites of colleges that offer such degrees, I feel like its more about basic programming with examples from games. This college offers game design degrees, for example. My question is, can I benefit from such a degree when I already have a degree in Computer Science, I already know programming, I'm already developing a game and finally, I have this site to help me when I get stuck?

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  • Should I use XNA (C#) or Java to create a basic game engine?

    - by Xboxking
    My project is to design and build a game engine (in just about 3 months). I've been looking at two options for this game engine, either make it with XNA (and C#) or Java. My experience with XNA/C# is zero to none, however I have been a Java programmer for around 4 years. I've had a little play around with both but I am still not sure what would be best to use (i.e. what would turn out better with my experience). XNA is obviously for making games and I would presume making a game engine would be slightly easier in this - however that said, there are numerous libraries available in Java that could be used for a game engine (such as lwjgl). What would be my best option and ideally produce the best results out of both XNA or Java? For your information, the game engine at the moment is a 2D one and is not too advanced (although I plan to extend it in the future). Thanks in advance for all answers!

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  • JavaScript Resource Management Design Pattern

    - by Adam
    As a web developer, a common problem I find myself tackling is waiting for something to load before doing something else. In particular, I often hide (using either display: none; or visibility: hidden; depending on the situation) elements while waiting for a background image or a CSS file to load. Consider this example from Last.FM. They overlay a semi-transparant PNG over each album art image so that it looks like it's inside a jewel-case. They let it load when it loads, so depending on your internet speed, you may see the art image by itself (without the overlay) temporarily. In this case, the album art looks fine without the jewel-case effect. But in similar situations, I have found that I don't want the user to see the site's design mangled as resources incrementally load. So, in rare cases I have hidden everything from the user until the whole kit and kaboodle has loaded. But this is often a pain to write out, and may force the user to wait for a pretty long time to see anything (besides "loading..." text). I can think of (and have used on occasion) some obvious solutions/compromises: Use some inline CSS so that as certain parts of the DOM load and render, they will immediately have the correct size/position/etc. Immediately render the navigation part of the site, so that if the user wanted to use the current page purely to get somewhere else, they don't have to wait for the rest to load. Load pixelated images first as placeholders for layout while lazy-loading higher quality images as replacements. Something quirky like using a cute animated gif to distract the user during a "loading..." phase. Show useful information as a reference while loading the full UI. (Something akin to Gmail Inbox Preview, etc.) (Sorry if my question was basically just asked and answered...) Despite all of these ideas, I still find myself hoping there are better ways of doing some of these things. So I guess what I'm looking for is some inspiration and/or any creative ways of dealing with this problem that you guys may have seen out in the wild.

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  • How do I remove SUN Java and use OpenJDK instead?

    - by Adel Ramadan
    As a programmer I use java for learning to code in Netbeans. I installed Sun java 6 long time ago over openJDK that came with my ubuntu just cause it seemed more responsive... Now that oracle left the repos I wanted something easy to handle to install and uninstall, so I want to Remove completely sun java 6 from my computer and set as default OPENjdk....and openjre. I already have installed OpenJDK and OPENjre...but not marked as default. Besides I want to clean Sun java from here, dont wanna get messy ^^. Running ubuntu 11.10

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  • How do I improve this design for dealing with intersecting date ranges and resolving date range conf

    - by derdo
    I am working on some code that deals with date ranges. I have pricing activities that have a starting-date and an end-date to set a certain price for that range. There are multiple pricing activities with intersecting date ranges. What I ultimately need is the ability to query valid prices for a date range. I pass in (jan1,jan31) and I get back a list that says jan1--jan10 $4 , jan11--jan19 $3 jan20--jan31 $4. There are priorities between pricing activities. Some type of pricing activities have high priority, so they override other pricing activities and for certain type of pricing activities lowest price wins etc. I currently have a class that holds these pricing activities and keeps a resolved pricing calendar. As I add new pricing activities I update the resolved calendar. As I write more tests/code, it started to get very complicated with all the different cases (pricing activities intersecting in different ways). I am ending up with very complicated code where I am resolving a newly added pricing activity. See AddPricingActivity() method below. Can anybody think of a simpler way to deal with this? Could there be similar code somewhere out there? Public class PricingActivity() { DateTime startDate; DateTime endDate; Double price; Public bool StartsBeforeEndsAfter (PricingActivity pAct) { // pAct covers this pricing activity } Public bool StartsMiddleEndsAfter (PricingActivity pAct){ // early part of pAct Itersects with later part of this pricing activity } //more similar methods to cover all the combinations of intersecting } Public Class PricingActivityList() { List<PricingActivity> activities; SortedDictionary<Date, PricingActivity> resolvedPricingCalendar; Public void AddPricingActivity(PricingActivity pAct) { //update the resolvedCalendar //go over each activity and find intersecting ones //update the resolved calendar correctly //depending on the type of the intersection //this part is getting out of hand….. } }

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  • Level design - Are games development degrees worth it? [on hold]

    - by Tristan
    I want to go into Level design or Environment design and wondering if degrees are at all worth it for this area, as long as you have a good portfolio. I'm currently on a "Computing and Games Development" course and I feel like dropping out because I am not enjoying it. It's mostly computer based, which I'm not doing that great at, and little games Dev. But I don't know what do to... I do already have some high level education with a "Level 3 extended diploma". Thanks.

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  • GWT RPC and GoDaddy Shared Hosting

    - by Mike Apolis
    Hi, I've deployed the sample Stock Watcher app to my GoDaddy Hosting site, and I get the error below. I've tried compiling the Project in Eclipse with JRE 1.5 because my Host is using jre 1.5. I think the issue is the "gwt-servlet.jar" is not compatible with jre 1.5. Can anyone confirm this. The project runs fine on my local machine using JRE 1.6. Unfortunately GoDaddy will not upgrade my shared hosting account jre to 1.6. GoDaddy Server Setup: Tomcat Version 5.0.27 JRE 1.5_22 Error: HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Error allocating a servlet instance org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java: 117) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java: 535) org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java: 417) org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java: 160) org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:300) org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:374) org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743) org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java: 675) org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866) org.apache.tomcat.util.threads.ThreadPool $ControlRunnable.run(ThreadPool.java:683) java.lang.Thread.run(Thread.java:595) root cause java.lang.UnsupportedClassVersionError: Bad version number in .class file java.lang.ClassLoader.defineClass1(Native Method) java.lang.ClassLoader.defineClass(ClassLoader.java:621) java.security.SecureClassLoader.defineClass(SecureClassLoader.java: 124) org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java: 1634) org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java: 860) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java: 1307) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java: 1189) java.security.AccessController.doPrivileged(Native Method) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java: 117) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java: 535) org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java: 417) org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java: 160) org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:300) org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:374) org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743) org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java: 675) org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866) org.apache.tomcat.util.threads.ThreadPool $ControlRunnable.run(ThreadPool.java:683) java.lang.Thread.run(Thread.java:595) note The full stack trace of the root cause is available in the Apache Tomcat/5.0.27 logs. Apache Tomcat/5.0.27

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  • What are your intentions with Java technology, Big Red?

    - by hinkmond
    Here's another article (this time from TechCentral) giving the roadmap of what's intended to be done with Java technology moving forward toward Java SE 8, 9, 10 and beyond. See: Oracle outlines Java Intentions Here's a quote: Under the subheading, "Works Everywhere and With Everything," Oracle lists goals like scaling down to embedded systems and up to massive servers, as well as support for heterogeneous compute models. If our group is going to get Java working "Everywhere and With Everything", we'd better get crackin'! We have to especially make more room in our lab, if we need to fit "Everything" in there to test... "Everything" takes up a lot of room! Hinkmond

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  • Is Java much harder to "tweak" for performance compared with C/C++?

    - by user997112
    Does the "magic" of the JVM hinder the influence a programmer has over micro-optimisations in Java? I recently read in C++ sometimes the ordering of the data members can provide optimizations (granted, in the microsecond environment) and I presumed a programmer's hands are tied when it comes to squeezing performance from Java? I appreciate a decent algorithm provides greater speed-gains, but once you have the correct algorithm is Java harder to tweak due to the JVM control? If not, could people give examples of what tricks you can use in Java (besides simple compiler flags).

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  • Is there a good book or articles to learn about 2D Game Design and Effects?

    - by user28015
    I am not looking for a read how to develop games and how to implement one. I am looking for a general about possible effects in 2D Games and about general design of modern 2D gaming. I have programmed several smaller games over the years and also read books like "Golden Rules of Game Programming" by Martin Bronwlo. So I know how to implement games. What I am looking for are 2 things: Finishing touches such as effects like explosions, particles etc. Not how to make them, but how to design them so it looks right and cool. How to make a 2D game feel "more right" so that users get a satisfying gaming experience. I played a lot of 2D games but I could use some more advice.

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  • What is the best database design for managing historical information? [closed]

    - by Emmad Kareem
    Say you have a Person table with columns such as: ID, FirstName, LastName, BirthCountry, ...etc. And you want to keep track of changes on such a table. For example, the user may want to see previous names of a person or previous addresses, etc. The normalized way is to keep names in separate table, addresses in a separate table,...etc. and the main person table will contain only the information that you are not interested in monitoring changes for (such information will be updated in place). The problem I see here, aside form the coding hassle due to the extensive number of joins required in a real-life situation, is that I have never seen this type of design in any real application (maybe because most did not provide this feature!). So, is there a better way to design this? Thanks.

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  • [Design Question] When to open a link on a new window?

    - by Ian
    Hi All, When designing a web application/web site, is there an accepted practice on when to open a link on a new window? Currently, if the site being linked to is outside the domain (say Google.com), I am always launching it on a new window. If the page being linked is within the same domain, I open it on the current active window. I've read somewhere the opening links on a new window explicitly is being frowned upon. Thanks!

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  • Are these advanced/unfair interview questions regarding Java concurrency?

    - by sparc_spread
    Here are some questions I've recently asked interviewees who say they know Java concurrency: Explain the hazard of "memory visibility" - the way the JVM can reorder certain operations on variables that are unprotected by a monitor and not declared volatile, such that one thread may not see the changes made by another thread. Usually I ask this one by showing code where this hazard is present (e.g. the NoVisibility example in Listing 3.1 from "Java Concurrency in Practice" by Goetz et al) and asking what is wrong. Explain how volatile affects not just the actual variable declared volatile, but also any changes to variables made by a thread before it changes the volatile variable. Why might you use volatile instead of synchronized? Implement a condition variable with wait() and notifyAll(). Explain why you should use notifyAll(). Explain why the condition variable should be tested with a while loop. My question is - are these appropriate or too advanced to ask someone who says they know Java concurrency? And while we're at it, do you think that someone working in Java concurrency should be expected to have an above-average knowledge of Java garbage collection?

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  • How to determine the right amount of up front design?

    - by Gian
    Software developers occasionally are called upon to write fairly complex bits of software under tight deadlines. Often, it seems like the quickest thing to do is to simply start coding, and solve the problems as they arise. However, this approach can come back to bite you—often costing time or money in the long run! How do we determine the right amount of up front design work? If your work environment actively discourages you from thinking about things up front, how do you handle that? How can we manage risk if we eschew up-front thinking (by choice or under duress) and figure out the problems as they arise? Does the amount of up front design depend entirely on the size or complexity of the task, or is it based on something else?

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  • To use Dart, the Java programmer has to work with 2 languages? [closed]

    - by Sridhar-Sarnobat
    When deciding on a technology to use for web apps, it's become a difficult choice between GWT and Dart and I am looking for guidance in deciding. GWT is a java programmer's dream because they don't have to learn a new language or have to worry about a separate IDE or extra plugin etc. GWT was sold using this value proposition - one didn't need to program in Javascript. But are Google making a U-turn and saying "go through the hassle of learning a new language" afterall? Or is it intended for there to be a Java to Dart compiler so that Java developers do not have to learn a new language? (this is not a rant, so I don't know why you are down-voting the question) Note: "the syntax is very similar" is not a justification. You could say why bother with GWT and just work with Java + Javascript directly.

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  • Android/Java learning resources for an experienced Objective C programmer?

    - by hotpaw2
    What resources are available for an experienced Objective C programmer to quickly and efficiently learn and get up to speed with Java, the Android SDK API's and Eclipse IDE? There seems to be at least one book and several web sites for experienced Java programmers who want to learn native Objective C programming, iOS UIKit and Xcode, but who don't want to waste time with a lot of basic programming concepts that an experienced Java programmer usually already knows. What are the available advanced educational materials for the inverse direction?

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