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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1answer
425 views

How to implement a genetic algorithm with distance, time, and cost [closed]

I want to make a solution to find the optimum route of school visit. For example, I want to visit 5 schools (A, B, C, D, E) in my city. Given the choice of five routes regarding what school I should ...
4
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4answers
3k 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 ...
3
votes
1answer
279 views

What do I have to do when using libraries with BSD license?

I am making a game using LWJGL and this is their license. What I don't understand is what must I do? I plan on making a game and distributing it, not the source code just the .jar file and maybe sell ...
1
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2answers
945 views

Instantiating objects in Java [closed]

I'm learning now Java from scratch and when I started to learn about instantiating objects, I don't understand - in which cases do I need to instantiate objects? For example I'm studying from TutsPlus ...
1
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1answer
757 views

Tomcat + Spring + CI workflow [closed]

We're starting our very first project with Spring and java web stack. This project will be mainly about rewriting quite large ERP/CRM from Zend Framework to Java. Important factor in my question is ...
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0answers
422 views

Embedded Tomcat Cluster

Can someone please explain with an example how an Embedded Tomcat Cluster works. Would a load balancer be necessary? Since we're using embedded tomcat, how would two separate jar files (each a ...
1
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2answers
185 views

If there's no problem treating a statement as an expression, why was there a distinction in the first place in some programming languages? [duplicate]

Why do we have the distinction between statements and expressions in most programming languages? For example, in Java, assuming f and g return ints, this still won't compile because it's a statement ...
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2answers
107 views

Need to organize words based on their components, any other way aside from brute force?

I'm not sure if this process has a name. I have some words (about 9,000). They are in Japanese, but I'll try to explain this using English words. I want to categorize the words by the components (in ...
1
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3answers
2k views

Can regexp be used to check for palindromes?

Can regexp pattern matching be used to check for palindromes within a given text in Java? My intuition is that in order to check for palindromes, we may need to remember the character that was parsed,...
1
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2answers
64 views

Should I reference a CopyOnWriteArraySet from the Set interface?

There are two ways to use a CopyOnWriteArraySet: // A Set<Object> set = new CopyOnWriteArraySet<>(); and // B CopyOnWriteArraySet<Object> set = new CopyOnWriteArraySet<>(); ...
0
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1answer
183 views

Prepared statement alternatives for this middle-man program?

I have an program that is using a prepared statement to connect and write to a database working nicely, and now need to create a middle-man program to insert between this program and the database. ...
1
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2answers
2k views

API always returns JSONObject or JSONArray Best practices

I'm making an API that will return data in JSON. I also wanted on client side to make an utility class to call this API. Something like : JSONObject sendGetRequest(Url url); JSONObject ...
2
votes
3answers
439 views

Decoupling software components via naming convention

I'm currently evaluating alternatives to refactor a drivermanagement. In my multitier architecture I have Baseclass DAL.Device //my entity Interfaces BL.IDriver //handles the dataprocessing ...
5
votes
2answers
751 views

Does this factory method pattern example violate open-close?

In Head-First Design Patterns, they use a pizza shop example to demonstrate the factory method pattern. public abstract class PizzaStore { public Pizza orderPizza(String type) { Pizza pizza; ...
0
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2answers
162 views

How to avoid or minimise use of check/conditional statement in my scenario?

I have scenario, where I got stream and I need to check for some value. If I got any new value I have to store it in any of data structure. It seems very easy, I can place conditional statement if-...
0
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3answers
533 views

How to change the state of a singleton in runtime

Consider I am going to write a simple file based logger AppLogger to be used in my apps, ideally it should be a singleton so I can call it via public class AppLogger { public static String file = ...
0
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2answers
133 views

API Class with intensive network requests

I'm working an API which works as "intermediary" between a REST API and the developer. In this way, when the programmer do something like this: User user = client.getUser(nickname); it will ...
1
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1answer
290 views

Implementation of instance testing in Java, C++, C#

For curiosity purposes as well as understanding what they entail in a program, I'm curious as to how instance testing (instanceof/is/using dynamic_cast in c++) works. I've tried to google it (...
1
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0answers
69 views

How to tidy up a massive spaghetti project [duplicate]

I previously asked this on StackOverflow, but was advised it was a better fit for Programmers. I have recently begun working on a codebase (as a Java developer) with the following characteristics: ...
2
votes
1answer
374 views

Design for object with optional and modifiable attributtes?

I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block ...
0
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1answer
141 views

Reflective discovery of an inner class in an API

Let me ask you, as this bothers me for quite a while but appears to be subjectively the best solution for my problem, if reflective discovery of an inner class for API purposes is that bad idea? ...
0
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3answers
699 views

Drawback of using static method [duplicate]

For methods that never access instance variable or static variable and they act just like a function (name-spaced) and they are deterministic base on only the input arguments , I want to ask, are ...
3
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1answer
3k views

The Observer pattern using the pulling mechanism

I was wondering about the following implementation of public void update(Observable obs, Object arg) while i want to send to all of my observer and update using notifyObserver() i and passing a ...
0
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1answer
295 views

How to generalize a classes that has identical function plus some additional function

I have some designing problems with my project. To illustrate my problem, I'll use the following two classes from my project. public class RAM_UserManagement{ private Map<int,User> userList; ...
1
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2answers
485 views

Should CountDownLatch be used for waiting for an event?

I have a situation here, where I have a loop that loops x amount of times. The value x is determined by the user. Everytime it loops, I want it to wait for a button click before continuing the loop. ...
0
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2answers
247 views

Which layer should service errors be handled in?

I am coding in a multitier architecture in Java, and I perform a query to a web service. Is it better form for the errors returned by the service be handled in the data access layer or in the ...
1
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1answer
497 views

I'm always reimplementing observer/subject code in Java. Is there a better option?

I'm always writing observer/subject interfaces in a particular Java project, e.g.: /** * Registers the receiver to the dispatcher. * When data arrives that the receiver can process, * it will be ...
1
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3answers
929 views

Protected variable & protected method in the era of TDD [closed]

I understand protected method is good for unit testing since you can easily mock by the class by overriding the protected method for the sake of testing. However, protected variable is just a global ...
2
votes
1answer
1k views

Does Java's Object.wait() really achieve nanosecond accuracy?

I was checking out the Java 8 standard library source code just out of curiosity, and found this in java/lang/Object.java. There are three methods named wait: public final native void wait(long ...
5
votes
1answer
619 views

Scheduling a few CPU-intensive tasks

I need to schedule a small number of CPU-intensive tasks to run every so often, reading from shared data and writing to dedicated buffers. I don't necessarily want to roll my own scheduling, but am ...
2
votes
2answers
385 views

Java: method takes varargs of unrelated types

I have a Java factory method with a varargs array of Objects at the end. The array can contain any combination of Strings and ScaledJpegs. The theory being that an HTML table cell can contain any ...
0
votes
3answers
152 views

Assigning responsibility for cancelling an Order

During a conversation with our Domain Expert we can across this feature: A Customer service agent can cancel an Order by decreasing its quantity. To cancel an Order we decrease its quantity by the ...
3
votes
2answers
620 views

Checked vs unchecked exception when validating documents in this service

I have a service that allow users to add dynamic content to a repository. So basically I have a generic Document class that contains a list of property for that specific object depending on what type ...
2
votes
1answer
286 views

Kerberos for key management?

We have half-implemented proper key management at our dev shop. We have a SOAP web service (the key management web service) that can be used to retrieve passwords for other systems. So for instance, I ...
3
votes
3answers
2k views

Is it considered bad practice to make a DAO call in an object's constructor?

I am trying to figure out the best design for instantiating an object which requires two separate calls to the data layer through a DAO. The object is not usable until these calls have been made (...
5
votes
1answer
785 views

When to declare @throws with a Scala annotation - abstract parent or concrete implementation?

In this StackOverflow question I asked about the behavior of the @throws annotation in Scala. Now that I understand how it works I want to ask about best practices with using it. Here's a repost of my ...
1
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1answer
413 views

java best practice to look for project essential files?

Usually when you do a new java project, there are several essential file such log4j properties file, other properties file and log file and you need to tell java where they are and where do you want ...
1
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1answer
299 views

OnClickListener good practice

Which one of the ways has better performance, or is a good programming practice, making the holder activity extend OnClickListener and make a Switch() clause for getItemId() or making one ...
-3
votes
1answer
400 views

Why is the JavaScript-language different in different programs/sites? [closed]

I'm kind of new to programming and i have a question that's been bothering me for awhile. Why is the JavaScript-language different in different programs/sites. I've used Codecademy to practice and i'...
9
votes
1answer
9k views

Naming convention: Final fields (not static)

Today I had a discussion with a co-worker about the naming of final fields in Java classes. In his opionion final fields should also be considered constants since their values won't change after the ...
2
votes
1answer
221 views

Learning to write DSLs utilities for unit tests and am worried about extensablity

I'm trying to simplify our unit tests with hand written DSL's. So far I have DSL's that walk developers through processing a service after setting up all preconditions and the construction of an ...
1
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0answers
74 views

Avoiding IllegalStateException in MVP when view is not ready yet

In an effort to improve my coding skills I am trying to make use of the MVP pattern in one of my first Android applications. It is going well but I have hit one issue that I am not sure what is the "...
2
votes
3answers
367 views

Uses for System.gc() in Java [closed]

In Java, there is a method called System.gc(), which calls the garbage collector (or rather, "suggests" to the JVM to run the GC). Are there valid reasons to call this method? I'm thinking that it ...
0
votes
1answer
500 views

Implementation of strategy design pattern

Here is my code: public class StrategyDemo { public static void main(String[] args) { Phone ipPhone = new IPPhone("1234", "ProviderA"); Phone tdmPhone = new TDMPhone(...
0
votes
2answers
593 views

Does the pattern of passing in one object instead of many parameters to a constructor have a name?

If you have a constructor that takes a lot of parameters, like this: public OrgUnitsHalRepresentation(List<OrgUnitSummaryHalRepresentation> orgUnitSummaryHalRepresentationList, int count, ...
4
votes
1answer
125 views

How to define the motion path of one object on a surface of the other one?

I have an uncommon problem. There are 2 3D objects, which are represented by arrays of vertices and triangles (.stl files). Each of them contains a big enough amount of vertices: 1-10 mln ones. The ...
0
votes
4answers
292 views

When copy/pasting private methods is it necessary to carry along the Javadoc? [closed]

So, unfortunately, I'm stuck with code where I'm doing this: @Override method A{ //calls private methods 1-8 } private method 1{ //copy/pasted } And so on for all of the private methods. I'...
0
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1answer
235 views

Does lots of Instance Variables within my class suggest flawed Design?

Ok so I am setting out to consolidate some learning I have been doing. What I am going to do is create a small game relating to a game I enjoy called Persona. For reference a persona you can think of ...
6
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1answer
911 views

Which patterns/architecture to apply for “Import Data, Process Data, Export Result”

I was wondering which architecture/patterns to choose for the following problem divided into three steps: Import TestScript Description from File (e.g. .xls, .txt) Process Described TestScript ...
2
votes
1answer
271 views

Should I separate a web api from the webserver?

Lets say I'm building a site similar to this or Quora (or some arbitrary blog-like site). I need a real-time component that will be using web-sockets/long-polling to notify the user of new posts, ...