Java is a high-level, platform-independent, object-oriented programming language originally developed by Sun Microsystems. Java is currently owned by Oracle, which purchased Sun in 2010.

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10
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1answer
372 views

Efficient way to represent hexagonal board logic for abalone-like games

I have to implement the AI for Abalone game and I'm wondering what is the best way to represent the board logic using Java without wasting too much resources in all checks and updates routines ...
6
votes
3answers
300 views

Design solution for communicating between multiple layers

We are developing a framework that has several layers and would be deployed in a multi-threaded environment. Each layer may have its own input/output data type. The top layer takes the input, performs ...
1
vote
1answer
68 views

excute Vs excuteOnExecutor [closed]

There are two ways to execute AsynTask, i.e., execute and executeOnExecutor. I already know that execute works serially and executeOnExecutor works in parallel. So my question is: Which one to use? ...
2
votes
3answers
120 views

Design a Queuing Solution with Clustering and Multiple Consumers

It is a Design Problem which I am listing out here. I have different set of business operations that are carried out for different business entities. Operations: Operation A Operation B Operation ...
1
vote
2answers
93 views

JUnit3 and JUnit4 in the same project (but different module)? [closed]

I have an Android project with a Gradle build. We've decided to commit to writing a vanilla Java implementation of our business logic (since we took care to keep that divorced form the Android ...
1
vote
2answers
141 views

Overriding methods by passing as argument the subclass object where the supertype is expected

I am just learning Java, and am not a practicing programmer. The book I am following says that when overriding a method, the argument types must be the same, but the return types can be ...
0
votes
1answer
49 views

Java Doc - Do fields also get documented?

This is a really simple question but oddly, I'm finding it difficult to get a definite answer.... What do you do with fields? Is this valid? /** * Keeps track of all usernames in the system. */ ...
0
votes
0answers
95 views

Best approach to save relationship mapping of country,state,city in orm

I am building a project in play framework java with jpa and I want set country,state,city dropdown fields in a form to be dynamic(from database).So only admin can increase or decrease the value of ...
0
votes
1answer
156 views

What'd be better? To add one more local variable, or to call a method twice in general case?

I have the method which returns java.util.Date inside the hibernate-entity class: package ua.com.winforce.loto_partner.commons.db.entity; @Entity @Table(schema = "pr", name = "publice") public class ...
2
votes
1answer
163 views

Object caching in this code too expensive?

I'm having some trouble with a game developed in Java which is kinda slow. I benchmarked it a little bit and found the problem: most of the time, the JVM is in the Object.<init>() since there ...
2
votes
2answers
304 views

Development on Android without using Java [closed]

As the title of this question suggests, I am looking forward to develop app(s) on Android platform without using Java at all. It doesn't mean I have some kind of vendetta against this beautiful ...
1
vote
1answer
68 views

JSP without .jsp-files?

I have a little project (a CMS) that was developed using .jsp-files in 2006. I moved in 2011 to JSF and had only one .jsp-file for the frontend. In 2014 I integrated the backend into the frontend ...
-1
votes
1answer
153 views

What's the returning a value in Java?

public void warning(){ System.out.println("Watch out!"); } public void warning(){ System.out.println("Watch out!"); return; } We must use "return" statement with void methods. Bot ...
0
votes
1answer
63 views

Reflection performance in this iteration of a (probably) large excel file

I'm wondering the performance of reflection in this situation. I'm iterating a (probably) large excel file (let's say 3000 max) which it's going to be done from time to time, and the implementation ...
0
votes
2answers
63 views

Which 'InputStream' subtype is used by 'Socket' type object here?

In the below server socket program, byte stream object is used to read data from client, as mentioned - InputStream in = socket.getInputStream(); public class SingleThreadTCPServer{ ...
1
vote
1answer
77 views

Query on java I/O BufferedOutputStream write() method

Below is the code that is written using byte stream non-buffer class FileInputStream and FileOutputStream with the usage of explicit user buffers. public class FileCopyUserBuffer{ public static ...
0
votes
1answer
179 views

Shortest path to visit all nodes [duplicate]

I am given a set of tourist attractions(nodes identified by x, y) and i need to find the shortest path to visit them. The way i thought of it, is i will ignore if there are streets available and ...
3
votes
1answer
80 views

Template pattern with varying input type in overridden method

I am trying to use template pattern to define a generic algorithm in java. But the method that needs to be overridden, takes an object as input. This object will vary depending on the concrete ...
0
votes
1answer
185 views

Whats the difference between byte and Byte? [duplicate]

Alright so of course, I know the differences. byte is a primitive and Byte is an object. Byte offers more functions but there is one thing I dont understand. Why would anyone create a variable using ...
2
votes
1answer
179 views

Why is close() implemented in InputStream/OutputStream?

It make sense to see close() as non-core functionality of stream objects. This is the reason this method is placed in interface Closeable. One evidence is that class ByteArrayInputStream does not ...
1
vote
2answers
69 views

Query on hiding implementation details in java

With the below piece of thread related code, I see that author of Thread class is hiding the details about the working of start() method. What a user of Thread class need to know is, class Thread ...
0
votes
0answers
71 views

vert.x message bus architecture

A large part of the vert.x architecture is around the message bus, and message passing between verticals. The main idea I guess being that I can create multiple modules (possibly in multiple ...
-1
votes
2answers
130 views

Initialize in Field, Constructor, or Argument

If I know what a field will be initialized to, should I initialize it in the field, constructor, or receive it as a parameter? For example, where should I initialize an ArrayList? Initialized in ...
2
votes
2answers
268 views

Unit testing and reality [closed]

I m actually studying Unit testing, reading some articles on the internet and trying to understand how it works exactly, but it's not very clear for me actually. What should I test ? I have seen ...
0
votes
2answers
200 views

What design pattern for changing interface?

Sorry guys, I should have clarified the fact that the modified method is abstract in Father. Then if the method signature changes, all its implementations in SonX shall also change(at least the ...
0
votes
1answer
99 views

Producing JSON objects from JPA entities in REST API

I have a REST service producing JSON and consuming JSON. A lot of this are simple CRUD operations. My initial idea was to simply use the DAOs directly in the controller: @ResponseBody() ...
2
votes
1answer
146 views

Why use a enum to create the singleton pattern [duplicate]

Why would you use an enum to create a singleton pattern? To what purpose would it serve over a conventional singleton pattern? I have seen the above used. The code uses an enum to create this pattern ...
2
votes
1answer
58 views

Applying initialization-on-demand holder idiom at variable level rather than class

I was looking for the idiomatic way to implement thread-safe lazy initialization for a configuration collection retrieved from the DB inside a Spring bean. I decided to adapt the ...
0
votes
1answer
83 views

Continuous Integration for different languages [closed]

So, I understand Continuous Integration in theory, and have used Beanstalk. However, I've been charged with creating the process at my current PHP shop. My hope was maybe PHPCI, since it looked ...
4
votes
2answers
243 views

Is it better to use strings or int to reference enums outside the java part of the system?

We were having a discussion at my work about the use of enums in Java. A coworker was arguing that when using enums on the server-side, whenever required we should use string to reference to it (for ...
0
votes
3answers
71 views

Best approach to implement an update operation of a container object?

I have an Invoice object wich may contain several FacturedServices objects stord as a list. In may interface, the user can edit an Invoice object, delete add or edit its FacturedServices list. Whe ...
0
votes
1answer
128 views

Dealing with several custom getters

I have a data structure with data units containing different types of data. I've wrapped the data in "Field" objects so that each field is able to independently parse user input in a desired way. ...
1
vote
2answers
207 views

When should we work on GC optimization?

So, I've learnt about how GC works and how can I monitor it via VisualVM, but my question is about why we should ever perform GC optimization? In our web project (JSF/Spring/Hibernate) we haven't ...
-2
votes
2answers
174 views

Why public access level method get overridden in java?

This question is raised with a clarification required to decide when to declare a method protected or public during class design of a package. My point is, if one needs to override a method of a ...
0
votes
2answers
204 views

Java card game design decision

I am making an application for a card game, with a standard 52-deck playing card. For now, I am writing a solitaire game with for learning purposes. I've had some experience making platformers and ...
4
votes
3answers
258 views

Why use arg type `class Object` instead of `Comparable[]`?

In the code below, I believe it would look more appropriate to make the method argument be of type Comparable[] instead of Object[]. The first reason it would be more appropriate is that one can be ...
0
votes
1answer
108 views

Is it possible to have a keyed dictionary stored on disk? [closed]

for example) would it be possible to be able to use the key of an item to access the item stored in a file out on disk (without searching through the whole file)? I'm looking fora general example of ...
0
votes
1answer
100 views

Matrices calculations on partial shape matching

I'm working in a shape recognition project where it is supposed for me to develop an application that receives two images: an original one and a sketch made by a user. I am supposed to detect contours ...
0
votes
2answers
165 views

Develop GUI and logic in a team the right way? [closed]

I am planning to start a small project with a friend. I will be developing the GUI using JavaFX in the MVC pattern and he will be responsible for the model/logic. My question is: how can we achieve a ...
0
votes
1answer
27 views

Using classes not designed for multiple sessions in servlet

I'm looking for a way to use a collection of Java classes in a servlet, which would provide some services to clients, but the classes were not designed with multiple sessions in mind, which seems to ...
0
votes
1answer
80 views

Can JUnit be used to test this project?

I currently have an interesting situation occurring with my code, and after hacking away at what turned out to be a dead end for the last two weeks, I'm here asking those smarter than I to educate me ...
2
votes
1answer
115 views

Is Singleton enough for a EMailUtil or there is any better implementation? [duplicate]

I am developing an application, where I have to send lots of emails for user account creations, validation, invites etc. I have implemented a static class EMailUtil which has different methods like ...
2
votes
1answer
66 views

Creating/updating entity save strategy

Please note: although I'm talking about Java in this question, what I'm asking about here should really be language-agnostic. I am dabbling in OR/M for the first time, and have cooked up the ...
1
vote
1answer
361 views

Programmatically extending Hibernate table/entity definitions in Spring, how?

I would like to know if there is a way —maybe with AOP— to extend table/entity definitions so that I can add functionality across the board that requires persistence. Let me explain what I want to do ...
3
votes
4answers
341 views

Why is the hashCode method usage of HashSet not specified in the API?

I was trying to debug my code which uses a HashSet and searching through the SO, I found out that I needed to override the hashCode method as well. The strange part is, checking the related API, I did ...
1
vote
2answers
153 views

Improve the speed of a Tomcat Server with MySQL

I'm developing an application with 3 sides, desktop (JavaFX), server (Tomcat) and Android. And a MySQL Database Server. The app receive mails and convert them into tasks. The tasks are sent to the ...
1
vote
1answer
262 views

Creating a calendar/planner program. Confused about OO logic?

I'd like to create a piece of software that has the functionality of a common written planner. To do this, it will have a Calendar. When planning the program, I became confused as to how I would ...
1
vote
3answers
236 views

Building a calculator using MVC

I've been programming in Java for about 6 months, and I thought a good and challenging test of my skills would be to build a GUI calculator. I have very recently heard about this MVC idea, and I ...
0
votes
2answers
191 views

Managing multiple JDBC connection

I have an application that connects to databases based on a json string that contains connection information. The json is sent just when the application starts. How do you manage such connection ...
0
votes
1answer
143 views

Is Default Package included in the Package Level Access?

I would like to know how the default package is defined in Java.I know how public and private access is defined but I don't know whether there is any default package access that is defined in package ...