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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2
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3answers
130 views

How do I show 'creates' in a UML class diagram?

Let's say my code is going to look like this: public class MyController { private Foo foo; private FooGenerator fooGen; //setters public void work() { this.foo = ...
-1
votes
0answers
38 views

Spring-Quartz scheduler throw NoSuchMethodException [closed]

I'm using Spring MVC to develop my project and I want to use quartz-schedule to set time for an method in controller. But there is java.lang.NoSuchMethodException occurred. This is my declared code: ...
2
votes
2answers
165 views

return a object without returning the reference

i'm having some trouble with returning objects and lists of objects. To problem is I want to return a object in my example an developer but I don't want to give the reference. What's the best ...
0
votes
1answer
60 views

how can the presenter or view interact with the model in the MVP pattern?

I'm learning the MV* patterns. MVP in this case. I'm trying to refactor an old android application into the MVP pattern to make things less tightly coupled, but I'm struggling one one concept. I know ...
0
votes
1answer
53 views

Using Websocket for a multiple-page website

Is using Websocket (in particular, in a Java, SpringMVC webapp, with the Spring Websocket support libs, but the question probably applies to any language) for a multiple-page website a bad idea ? ...
2
votes
2answers
191 views

Problems with OO design for application with pluggable components

I'm trying to refactor an ugly code and make it easly extendable in the future. The application should be nothing else but a series of components that have input(s) and output(s). The components ...
5
votes
2answers
189 views

Does sun.misc.Unsafe give access to the system or just the JVM?

Please note: Although this question involves microcontrollers, it is at its core, a Java question, and so I believe it can be answered by any battle-weary Java guru. I stumbled accross this blog ...
-7
votes
0answers
67 views

getting square root(without using Math.sqrt function) using iteration loop or recursion [closed]

This is a problem mentioned in one of exercises in Think Java book. The problem is to get a square root of a number that has been input. ...
0
votes
2answers
655 views

HTTP Session: A single object or multiple?

I tested two approaches to store session data: The classic: 1 key, 1 object (And every key as static final String in a class) "user" --> UserObject "preferences" --> List ... An ...
3
votes
3answers
157 views

Design suggestions for converters in Java

I'm trying a set of converters which will convert an object to some older form. And there are different objects which are converted. By older form I mean changing the values of some fields and in case ...
6
votes
3answers
179 views

Advantage/Disadvantage of having all variables declared in a JUnit Test

I've been writing some unit tests for some new code at work, and sent it off for a code review. One of my co-workers made a comment about why I was putting variables that are used in a number of those ...
-1
votes
0answers
35 views

Tcp server language choice [closed]

Is there any reason to use a specific programming language for TCP server programming? Or java, c# can achieve same as c++ without any noticeable performance loss?
2
votes
1answer
94 views

What is the motivation behind the @ImplementedBy annotation in Guice?

I recently read about the @ImplementedBy annotation available in Google Guice. It allows the programmer to specify a binding between an interface and its implementation for future use in dependency ...
5
votes
2answers
2k views

Why multiple calls to same classes' Constructor from within a Constructor wouldn't work?

Please have a look at following snippet: public class Foo { int digit; String name; Foo (int d, String n) { this(d); // cannot do following. //compile-time error: Constructor call must ...
1
vote
0answers
42 views

Will using a pure MQTT approach be the right decision?

I plan to provide additional functions for a closed-source 3rd party point of sales application. That application is used in restaurants, is run on Windows and uses dbase style databases. I know the ...
19
votes
6answers
7k views

Is it a bad practice to have an interface to define constants?

I am writing a set of junit test classes in Java. There are several constants, for example strings that I will need in different test classes. I am thinking about an interface that defines them and ...
3
votes
2answers
399 views

How should I annotate, that a class is immutable in Java?

I recently stumbled upon how useful immutable objects are and that e.g. if you pass elements to a constructor and your class should be immutable, you have to copy these elements if they are not ...
14
votes
2answers
1k views

Declaring a class final? [duplicate]

I like my code to be written well; however, I have run into not really an problem, but more of a question about conventions. Say I have this class. public class Test { public void doStuff() { ...
0
votes
0answers
27 views

Run fat jar as a service on Amazon Linux EC2 instance using Ansible

I want to deploy a Ninja app to an EC2 Amazon Linux instance using Ansible. Being a Linux noob and completely new to Ansible, I wonder what the best way would be to start the app via Ansible as a ...
0
votes
1answer
37 views

Java: Weighted Selection help [closed]

I have this code that randomly selects a item from a enum. Each of the enum items have a integer weight to it. The higher that weight is, the higher chance that item has of being picked. Here's what ...
0
votes
1answer
141 views

I need a data structure for a card game

I am programming a card game in java, and unsure what data structure I should use for the player's hand. I considered using an array, with one integer to traverse the array and another integer to ...
7
votes
3answers
7k views

How is multi-threading different in a Java based Web Application vs Stand-alone Java Application

I am fairly new to Java and my experience is limited to Web Based Applications running on a Web Container (Jboss in my case). Am I correct in saying that for Web Applications the web container takes ...
7
votes
4answers
15k views

Do I need to know servlets and JSP to learn spring or hibernate or any other java web frameworks?

I've been asking a lot of people where to start learning java web development, I already know core java (Threading,Generics,Collections, a little experience with (JDBC)) but I do not know JSPs and ...
0
votes
3answers
235 views

What arguments are there to use a coding style for each distinct language? [duplicate]

I recently had a discussion about our coding style for C# projects. Two things in particular were very hard to agree upon. Method Naming C# has the de-facto standard of naming (at least public, ...
2
votes
1answer
121 views

Does the LGPL apply if I rewrite a portion of JasperReports in C++?

I would like to rewrite a portion of the JasperReports library in C++. The library will read from the same XML format used by JasperReports. If I integrate this C++ library to my proprietary ...
-1
votes
0answers
6 views

eclipse acting weird when creating methods [migrated]

I don't see what could be wrong here, I was working on a different method but had some problems so I tried to simplify it to check where could the mistake be but I ended going up into this very simple ...
0
votes
2answers
224 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. ...
0
votes
1answer
89 views

Should a comparison method ever return the same type back as it's comparing?

First, this is homework, but no, I'm not asking for anyone to do any code for me. My course start date isn't for another month (it's online), so I can't ask for clarification. I thought I'd see if ...
1
vote
1answer
49 views

How do I effectively test, and log, network status with a Java Application?

I want to write an application (in Java) that basically detects when I lose my internet connection, and then log the time. To make things more challenging, I'd like to figure out the point of failure. ...
7
votes
3answers
9k views

What is meant by Scope of a variable?

I think of the scope of a variable as - "The scope of a particular variable is the range within a program's source code in which that variable is recognized by the compiler". That statement is ...
-5
votes
3answers
107 views

Is it possible to Style a csv file? [closed]

I am generating a csv file in java and want to use MS Excel to read it. Unfortunately it looks very simple, with no formatting. Is it possible to add styling to a csv file (using java) so that when ...
3
votes
1answer
56 views

Do I need a web-service for this case? Data-synchronization over multiple clients

I'm new in this area and a little bit confused about my current thoughts on a web-service implementation for my application. I want to synchronize all connected clients with the current data on a ...
2
votes
1answer
238 views

How to efficiently handle related data in MVC?

Talking about MVC with servlets and JSP's, in a context about products and manufacturers , when querying the application for a list of products: the servlet loads a list of products from the ...
0
votes
1answer
118 views

Changing the Garbage Collector on your JVM [closed]

My understanding is that the JVM specification only defines the behavior of a garbage collector, but does not provide implementation details. This means it is up to the JVM implementation to build the ...
2
votes
0answers
76 views

Cross-compiling Java app to run directly on ARM

Please note: although I am using ARM SAM3X8E in this example, I'm just using that as a concrete example, and the answer to this question could easily be given using any other MCU such as AVR, etc. I ...
2
votes
0answers
34 views

Embedded tomcat cold deployment without service disruption

I have the following scenario. For various reasons I chose to use embedded tomcat for my rest backend that will form a cluster of AWS machines. I will want to deploy fairly frequently updates ...
0
votes
2answers
124 views

What is the best type to represent a number in java and why? [closed]

I am developing a dynamically typed, interpreted programming language, which is interpreted by a runtime written in Java. As Java is statically typed, I need to define how the numbers used in the ...
1
vote
1answer
46 views

role based access control model in object oriented

I want to prepare a swing application. I am designing a role based access control model in mvc design. When a view wants to request something from a controller, how can this request be realized in ...
2
votes
1answer
159 views

Best practices for programmatic describing of behavior of complex input forms

We have a complex web form (we use GWT/GXT stack) with lots of input elements of different types (text fields, selects, checkboxes, buttons), and behavior of these elements depends on each other. Now ...
1
vote
1answer
195 views

Adding a graphical view to a system

I currently have an program in Java that simulates railway movements. Essentially, trains arrive on platforms, pick up and drop off passengers, and then proceed, respecting signalling where possible. ...
2
votes
2answers
497 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 ...
2
votes
2answers
393 views

What is the difference between Callable<T> and Java 8's Supplier<T>?

I've been switching over to Java from C# after some recommendations from some over at CodeReview. So, when I was looking into LWJGL, one thing I remembered was that every call to Display must be ...
0
votes
2answers
417 views

Emulation of MMU accessing the contents of the registers

I'm having a play around with emulating a simple old CPU. I've set the structure up, so far anyway, as follows: The device is the main and creates an instance of the CPU. The CPU then creates ...
0
votes
2answers
72 views

Handling DomainExceptions using REST endpoint

Suppose I'm doing some DDD. Now, I have a microservice reflecting a bounded context/a part of a bounded context. Now, suppose there is a REST endpoint: '/somedomainmodel/someaction' My API user is ...
35
votes
5answers
3k views

Java dev learning Python: what concepts do I need to wrap my head around?

Background: I've run through a few tutorials and written some small projects. All is going well enough using Google and StackOverflow. Several times in the last few days I've found myself wondering ...
10
votes
2answers
437 views

Java: why is there a Comparator interface but no Hasher and Equator?

This issue is most apparent when you have different implementations of an interface, and for the purposes of a particular collection you only care about the interface-level view of the objects. For ...
2
votes
1answer
269 views

Large Scale Application Development in Android

Since, I am fairly new to large scale app development in Android and Java, I thought I would ask for advice. My team is faced with developing a prototype of a fairly complex medical software. ...
3
votes
1answer
121 views

What was the date of the Java Alpha and Beta releases

The date of the public 1.0 release of Java is easy to find: January 23, 1996. But there were public Alpha and Beta releases before that, and in December 1995 Java already appeared on the list of Time ...
24
votes
5answers
2k views

Why do C# and Java use reference equality as the default for '=='?

I've been pondering for a while why Java and C# (and I'm sure other languages) default to reference equality for ==. In the programming I do (which certainly is only a small subset of programming ...
4
votes
4answers
325 views

Legitimate cases of having .equals() behaving inconsistently with .compareTo()?

Java documentation says it's "strongly recommended" to have them behaving consistently. But are there legitimate cases of java/c#/python/etc Object.equals() method behaving inconsistently with the ...