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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Passing data between hundreds of objects in java [closed]

Currently, I'm working with a group on building a model. This model simulates interactions between many "agents" in a region. Agents can be any entity such as a city, a farmer, a business etc. Each ...
5
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2answers
2k views

Why to declare a String (as final) and then use it?

In a typical spring mvc validator class, while inserting an errorCode value in the Errors object, what difference does it make between using a String (props.somefield.req) like so errors.rejectValue("...
2
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3answers
309 views

Duck typing in statically-typed languages

Is it a fair assumption to say that an overloaded constructor for a class can be thought of as a 'duck' for duck typing? Let's say that ClassA has an overloaded constructor, it would stand to reason ...
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2answers
3k views

Is “continue” and “break” in loops antipattern/bad practice in Java? [duplicate]

I see the main purpose of continue in programming, it can get you out from the rest of loop steps like: while(condition1){ ... code ... if(!condition2){ continue; } ... code ... if(...
2
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1answer
661 views

Several enum classes that declare constants with the same names

I'm working on a Java library for sorts for Magic: the Gathering. Well, without going into a lot of detail, in the game there are five different colors of magic: white, blue, black, red, and green. ...
1
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1answer
196 views

Web-services REST security clarification

I'm newbie of web services programming and I have some problem to understand how to work authentication/security for REST WS pattern. I had read about OAuth but I haven't understand how it work in ...
15
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12answers
3k views

Why use getters only as opposed to marking things final? [duplicate]

I'm working in a java role after working a couple years in functional programming. Our company was bought by google and I took a java role after the acquisition. Coming back to java as a polyglot ...
5
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2answers
364 views

What's the easiest way to comply with open source licenses? [closed]

I'm really confused by all the open source licensing details like "I wrote a web application, which should run on a computer not owned by me. My software uses the library/language xxx. Is this ...
34
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2answers
5k views

Do modern languages still use parser generators?

I was researching about the gcc compiler suite on wikipedia here, when this came up: GCC started out using LALR parsers generated with Bison, but gradually switched to hand-written recursive-...
0
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1answer
100 views

Confusion about instance in an interface

I'm trying to learn OGSi framework (Equinox distribution). I have registered my service, but I'm confused about a piece of code that I've copied: IAgendaService service = new AgendaService(); What ...
3
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2answers
4k views

What happens if I close an InputStream that is passed as an argument?

I have read that Java is pass-by-value, and I've been reading about it in this question at StackOverflow, but I'm still a bit confused, regarding the close() or shutdown() methods in various classes. ...
0
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1answer
873 views

Differences between Direct, Composition, Aggregation, and Temporary Association

I am looking to take my java certification very soon, and I have a question about the different types of associations described in the official oracle guide book. The book describes the 4 as the ...
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4answers
528 views

Why can you have statefulness inside a static class in java?

I was playing around with Java today and I read about static inner classes. Why can you have 'statefulness' inside of a static inner class. For instance: class outerClass { static class ...
0
votes
3answers
5k views

Nested maps vs. combined keys

in the project I am currently working on we had three different types of prices depending on the age of the user (adult, child, etc...). So we had on the DB a table looking like this: PRICES type ...
0
votes
1answer
134 views

Huge long addition overhead compared to Native call?

A run a simple test JDK 1.7.0_45 (Windows 7, 64bit): Test 1: long start = System.nanoTime(); for (int i=0; i < 1000000; i++) { System.currentTimeMillis(); } elapsed = System.nanoTime() - ...
4
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1answer
396 views

If a dependency is not in the maven repository should I add it to source control?

One of the jar files that I use in my code is not in the maven repository(and yes I tried to avoid using it). I have installed it locally so when I build the project it gets picked up by maven. I also ...
3
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1answer
3k views

Builder pattern inside interface. Bad design decision?

I am having trouble evaluating an implementation of the builder pattern I just came up with. The context is an API library, so I am trying not to expose any implementations in order to have a stable ...
0
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1answer
450 views

Interactive session with a command line program using Java?

I plan to write a website frontend for a free computer algebra system (Reduce, http://reduce-algebra.com/). On the webserver I have a Java virtual machine running, and Reduce is also installed. I can ...
41
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9answers
4k views

Programming for future use of interfaces

I have a colleague sitting next to me who designed an interface like this: public interface IEventGetter { public List<FooType> getFooList(String fooName, Date start, Date end) ...
0
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1answer
187 views

Why does this method return 2 values if I only ask for one and there is no sort of conditional statement anywhere?

I'm writing this very simple program from this one PDF called Think AP Java, and I can't seem to wrap my head around this: When I write public static double method_1(double x) { double ...
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votes
1answer
1k views

How Jetbrain Phpstorm IDE is working without installed java? [closed]

As far as I know Jetbrains PHPStorm is programmed in Java but while I don't have Java installed in my Windows 7 PC, PHPstorm is installed and working without any problem. How It's done?
0
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2answers
887 views

how to approach pharmacy software project [closed]

I would like to complete a pharmacy software proof concept. But I have a few questions I do not know. Physician information In order to refill or dispense a new RX the software needs to have access ...
0
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2answers
3k views

Way for java program to read file from when it was stopped

I am working on an application that reads a log file, looks for a specific string, sends alert emails and saves data from the file into a database. The reading functionality is working well, but I am ...
-2
votes
1answer
182 views

How can I perform a logical test to ensure that MY CUSTOM ERROR gets thrown instead of the NumberFormatException? [closed]

I am working on something that should be fairly simple. I have 95% of my program working, but one piece is still not fulfilling the requirement. (FYI, this is for a homework assignment, but I will ...
3
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2answers
169 views

Program Design clearness vs convenience

I've recently disputed with my colleague about the following situation: I've developed a framework that processes the resources (in java, although its not really important). It goes (simplified, ...
4
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3answers
203 views

Returning results of method on batch list?

The title is a bit vague so I'll try to elaborate. I have a function makeFoo(int bar) -> returns Foo or throws Exception. I also have a batch version of this makeFoos(int[] bars) -> ...
0
votes
3answers
292 views

When to use default access modifier?

I want to understand, from design point of view, in what situations I should use default access modifier, and when I shouldn't. I found this related question, that provides some basic explanations, ...
0
votes
1answer
259 views

Multilayered enterprise application use of JAXB objects

I am asked to refactor and maintain an enterprise application. Normally I'm used to using the MVC design pattern. This time however, I'd like to separate everything into layers (multilayered ...
1
vote
2answers
801 views

Is it okay if we use an arbitrary string as UUID?

I found the tutorial of client (android) and server (pc) bluetooth tutorial from here. But my question is about the UUID. Is that okay if we define it randomly without the proper format? Because I ...
0
votes
1answer
390 views

Automatically create or update object in database

I have a database class with the following interface: public Database { //returns false if p (its ID) is already available //otherwise adds p the the list and returns true public boolean ...
6
votes
2answers
2k views

Understanding JAVA generic keyword 'super'

Recently some people said that I was wrong when I explained why one cannot insert a Number object into a list declared as List<? super RationalNumber>. (This assumes that RationalNumber is a ...
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votes
1answer
73 views

Is any one of these the right way to write a license for your opensource project forked and modified from an existing one with different authors?

I've used parts of source from an existing Java library project with what appears to be a 3-clause BSD license. I've made significant changes to the library which makes it possible to use it in a new ...
3
votes
2answers
145 views

System state design composition

Consider the following Java code: public class HumanStateImpl implements HumanState { private boolean alive; private Color skinColor; // getters and setters, other state fields @...
1
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1answer
566 views

Pros and cons of custom exceptions [duplicate]

This may be an pointless question based on opinion, style, and context but I've been racking my brain trying to decide whether or not to make use of custom exceptions and would love to hear some pros ...
10
votes
2answers
3k views

Why does C# have much more features than Java? [closed]

Please note that this isn't meant to be a Java vs. C# argument. I'm a Java programmer with no C# experience, asking just out of curiosity. I did some reading on C#, and it seems it has much more ...
2
votes
1answer
1k views

How to design extension mechanism for java app

I have an application where I have a set of core features. The application itself HAS to work in core only mode. I would also want to make the application extensible such that, when certain jar/...
0
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0answers
15 views

Select design pattern - user stage [duplicate]

I'm struggling to point a finger into the right design pattern. I have a web site which user can register and interact with the system. I want to add the following abilities to a user: Each user ...
5
votes
3answers
4k views

In Java, what are some good ways to separate APIs from implementation of *entire projects*?

Imagine you have a software module, which is a plugin to some program (similar to Eclipse) and you want it to have an API which other plugins can call. Your plugin is not freely available, so you want ...
-1
votes
1answer
147 views

What is the recommended way to go about porting large code bases? [closed]

I am currently porting a large library (150+ files, 15k+ LOC) from Javascript to Java. Fortunately, the original library is already very object-oriented, so this has largely been a matter of ...
19
votes
4answers
1k views

How bad is it calling println() often than concatenating strings together and calling it once?

I know output to the console is a costly operation. In the interest of code readability sometimes it is nice to call a function to output text twice, rather than having a long string of text as an ...
2
votes
1answer
623 views

Structuring a storage system for a game

I am working on a multiplayer game, where a player has many storages to store items in. Storage Storage is the system that allows the user to deposit items, and take them back. Example of storage ...
0
votes
1answer
719 views

Dynamic query in MySQL

I'm doing a J2EE web application with Struts2, MyBatis and a MySQL database, so what I want is to allow the user to be free to choose different parameters to perform a select to a table in the ...
1
vote
3answers
202 views

w3c library license: does it prevent the inclusion in/distribution with paid software?

From W3C Software Notice and License: Permission to copy, modify, and distribute this software and its documentation, with or without modification, for any purpose and without fee or royalty is ...
4
votes
1answer
271 views

Database Password problem when using GIT to manage project that uses Spring to initiate Datasource

I use Spring Framework to code my Web Service, using Dependency injection to inject a DataSource bean into the DAO bean that will be used by the Web Service. I have all the database properties(Url, ...
5
votes
1answer
1k views

In Java, why use bit hacks when non-bitwise technique it is more readable?

Is there any legitimate use for bit manipulation hacks in higher-level languages such as Java? I can see them being useful in speed-sensitive low-level and computation-intensive programs, e.g. ...
0
votes
2answers
1k views

DTO - service layer - statelessness best practices interfering with each other

I am designing a REST API coupled with a service layer that takes DTOs as input and produces them as output. This works fine for most service calls where the DTO is used to access an underlying ...
2
votes
1answer
464 views

How should object identification be managed?

I have a java/swing application in (hopefully good) MVC structure. Here is a overview of my model classes: One or more workers may work at one working location and one worker may work at different ...
36
votes
6answers
5k views

Good or bad practice to mask Java collections with meaningful class names?

Lately I've been in the habit of "masking" Java collections with human-friendly class names. Some simple examples: // Facade class that makes code more readable and understandable. public class ...
20
votes
4answers
2k views

How can I use unit tests and TDD to test an app that relies mostly on database CRUD operations?

At work, one of my projects is mostly about taking data passed in from an external client and persisting it in a database. It's a Java enterprise app using JPA and most of our logic revolves around ...
3
votes
2answers
2k views

IllegalStateException vs. IllegalArgumentException

In have written a function which expects the caller to pass in a configuration file like XML. Then I parse this given file and extract something which i then return. In this function (at least) two "...