I read this SO post after I wrote out the title but still decided to go through with the question on bug-proof implementations of equals in Java. This is my normal implementation @Override public boolean equals(Object o){ if(o == null) return false; if(o instanceof CompositePk == false) return false; ...
So far, my program draws many rectangles and the locations of the rectangles are random (not nice). How can I place the rectangle in grid order so that it look appealing? ...
Currently, each web service for our application has a user parameter that is added for every method. For example: @WebService public interface FooWebService { @WebMethod public Foo getFoo(@WebParam(name="alwaysHere",header=true,partName="alwaysHere") String user, @WebParam(name="fooId") Long fooId); @WebMethod public Result d...
We have a Java web application that sporadically fails to find cryptographic libraries. Currently restarting the application fixes the issue. The following expections appear in the logs, see below for full stack trace. java.lang.InternalError: Could not start up the CDSA libraries. java.lang.NoClassDefFoundError: Could not initialize c...
This program I'm making for a COSC course isn't compiling right, I keep getting the error: Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 2 at java.lang.String.substring(String.java:1765) at VowelCount.main(VowelCount.java:13) Here's my code: import java.util.Scanner; public class V...
I have an application that uses a properties file that was added by hand at the /project/bin folder (Eclipse project). The application locates the file using: this.getClass().getClassLoader().getResourceAsStream("filename.properties") Now I want to add this file in Eclipse, so it's actually part of the project. In which directory shou...
For fun, I'm going to write my own implementations of common data structures like Linked List or Binary Sorted Tree. Are there any good test suites that already exist that I can use to make sure they are fully living up to their contracts? (It probably wouldn't be that hard to test them myself, but if it's already been done I don't want...
I've been trying to learn about events/delegates, but am confused about the relationship between the two. I know that delegates allow you to invoke different functions without needing to know what particular function is being invoked. (eg: a graphing function needs to accept inputs that are different functions to be graphed). But I don...
Before I look through my generic data structure for a value's index, I'd like to see if it is even an instance of the type this has been parametrized to. But Eclipse complains when I do this: @Override public int indexOf(Object arg0) { if (!(arg0 instanceof E)) { return -1; } What is the better way to do it? This is the error mes...
Hi. We have an XML that needs to be converted to an object and vice versa. Something like Xstream does. Until now we were using Xstream to marshall and unmarshall the object/xml. However the problem is that an object that corresponds to XML in xstream, needs to have all the tags as attributes; else if XML contains any extra tags which ...
I want to devlop simple image application in java. I need to display the image without anything around it. That is, there should be absolutely no application frame or title bar or anything else. When I open the image in this application, all I will see is the image floating on my screen. In should when my application shold work like go...
to use @autowired. in xml, i only need to included <context:annotation-config /> ? is there any other tag i need to put ? need to put componenet-scan ? weird, i get error below ERROR - ContextLoader.initWebApplicationContext(203) | Context initialization fa iled org.springframework.beans.factory.BeanCreationException: Error creat...
Hello All, When i should go for wrapper class over primitive types? Or On what circumstance i should choose between wrapper / Primitive types? ...
Just wondering if this and other related functions like those Integer is one of those things that one should not be bothered with and just go with Long a = 1L; simple and straightforward. ...
Hi, I am facing an issue in handling an object in session. I store an object in the session like this.Assume object is the name of the object.I do this in my action class if(object!=null) { session.settAttribute("objectName",object); return mapping.findForward("success"); } else { return mapping.findForward("failure"); } I map both...
i am looking to do devlop the floowing application. how to go abt it? Scan the system for installed webcams and their supported video modes. Let the user select a cam and a video mode. Displays a video of the camera. Starts a frame grabber/processor, it doesn't have to do nothing for now. I want to have the possibility to elaborate fra...
Kindly assist here, the getParameter is only printing the first portion of the String element in the tag. here is the select tag <select name="ActionSelect" id="ActionSelect" > <%Iterator itr;%> <% List data = (List) request.getAttribute("data"); for (itr = data.iterator(); itr.hasNext();) { String value = (String) itr.next();...
My question refers to whether or not the use of a ReentrantLock guarantees visibility of a field in the same respect that the synchronized keyword provides. For example, in the following class A, the field sharedData does not need to be declared volatile as the synchronized keyword is used. class A { private double sharedData; p...
Hi, I'm currently writing an application that actually acts as a "cut" tool for 3D meshes. Well, I had some problems with it now which I am clueless on how to solve, since it is my first application. I have loaded a model from an object file onto the canvas, then on the same canvas, I use the mouse drag event to draw lines to define t...
I have a Java application that runs on Mac and Windows, directly off a CD/DVD with no installation. Now, I need to store a file containing per-user data (think favourites etc.) somewhere on the local file system, so that it can be written to. So, where do you think is a good location for this file? I am thinking something like: <USER_...