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.

learn more… | top users | synonyms

1
vote
2answers
163 views

Designing Message class in Java

I'm writing a class for Message. Message comes with Header and Payload. Header has following fields: Version Type For Type "XYZ", the following Payloads are allowed. Configuration Metafile ...
5
votes
2answers
171 views

How do I deal with the following technical issue? [closed]

I am a Java Programmer and I am relatively new to Java(1 Year). I am working for a small startup company. My problem is a bit strange and I am facing it a bit difficult to deal with and explain also. ...
3
votes
3answers
112 views

Would implementing a “Throwable Event System” be abusive?

I have been thinking for a couple years now about using Throwable events and implementing a sort of event system that uses throw to dispatch an event, or let a different method handle it with throws. ...
-2
votes
2answers
152 views

How would you structure your code for a Neural Network? [closed]

I understand how Artificial Neural Networks work. However, implementing one in code is quite another thing. How would you go about designing the classes and data structures? I found one great ...
0
votes
0answers
22 views

How to illustrate the difference between forward and backward compatibility [duplicate]

Please correct me if I'm wrong, but a new version that can run old code is backwards-compatible and an old version that can run new code is forward-compatible (like an old B/W television can receive a ...
0
votes
2answers
79 views

Getters with data conversion in Java VOs

I am working on a standard Spring application where DAO layer returns entities to service layer and service layer returns VOs to other services and controllers. In a certain scenario, we have a VO ...
3
votes
2answers
152 views

Domain object model: query by id vs object

Let assume I have two simple model classes: Product and Brand It is obvious I have a query method in Product class like this Product product = Product.findById(123); What if, I want to query ...
0
votes
0answers
38 views

Handling server failure using serialization

In my program, there is a central server, and I want to store its state. I'm using serialization for this, I am serializing the data after every 2,3 seconds. So that whenever server fails, it can come ...
1
vote
1answer
133 views

Differences in design/thought process for OO in Java and JavaScript [duplicate]

Despite sharing a similar name and syntax, Java and JavaScript are quite different. However, they both have Object Oriented features. As a JavaScript novice, the main differences that I can see ...
2
votes
3answers
158 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
vote
3answers
198 views

Using prefix/postfix increment operator for simple incremental array access rather than actual index numbers

I cannot decide which method is better with consideration of both readability and fault-tolerance. Method #1: Object[] objects = getArrayOfKnownLength(); int i = -1; someMethod(objects[++i], ...
-2
votes
1answer
91 views

Java - Concept question: LinkedHashMaps vs POJOs?

EDIT: I'm just going to ask a single question instead of presenting a problem and asking for advice on a specific design decision in the solution. Given a batch of data from a database, collected ...
2
votes
2answers
201 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 ...
1
vote
2answers
177 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 ...
4
votes
5answers
516 views

Is it okay to go against all-caps naming for enums to make their String representation simpler?

Several times I've seen people use title-case or even all lower-case naming for enum constants, for example: enum Color { red, yellow, green; } This makes working with their string form ...
0
votes
1answer
103 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 ? ...
5
votes
2answers
228 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 ...
1
vote
0answers
83 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 ...
61
votes
9answers
10k views

How do you avoid getters and setters?

I'm having something of a hard time with designing classes in an oo way. I've read that objects expose their behavior, not their data; therefore, rather than using getter/setters to modify data, the ...
3
votes
3answers
169 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
303 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 ...
15
votes
2answers
2k 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
59 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
43 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
224 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 ...
3
votes
1answer
196 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 ...
0
votes
3answers
247 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
138 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 ...
0
votes
1answer
103 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 ...
0
votes
1answer
131 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
139 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
50 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
138 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 ...
3
votes
2answers
168 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 ...
1
vote
1answer
89 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 ...
1
vote
1answer
128 views

Java partial enum backed by the database

I have following problem: need to use enum in my java code, since I'll have to ask in my business logic things like if(someting == enumname.VALUE_ENUM){... but I don't have all the enum types at the ...
9
votes
6answers
465 views

Does it always make sense to “program to an interface” in Java?

I've seen the discussion at this question regarding how a class that implements from an interface would be instantiated. In my case, I'm writing a very small program in Java that uses an instance of ...
3
votes
1answer
132 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 ...
4
votes
1answer
274 views

Is Collection.stream().filter().forEach() inefficient compared to a standard for each loop?

IntelliJ IDEA recommended to me just now to replace the following for-each loop with a Java 8 "forEach" call: for (Object o : objects) { if (o instanceof SomeObject) { ...
0
votes
0answers
24 views

Classes, Datatypes and replicating Methods [duplicate]

I've gone from writing code procedural-style to object-oriented recently and during my development as an object-orientated programmer I have made a few mistakes. What I have been doing is, inside my ...
12
votes
2answers
654 views

Java: why do collections accept a Comparator but not (a hypothetical) 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 ...
27
votes
4answers
3k views

Why is .compareTo() in an interface while .equals() is in a class in Java?

I want to know why the .compareTo() is in the Comparable interface while a method like .equals is in the Object class. To me, it seems arbitrary why a method like .compareTo() is not in the Object ...
3
votes
2answers
196 views

Best strategy to find the root cause when exception is swallowed by 3rd party

I am sure we have all run into a scenario where a 3rd part API complains with an incomplete stack trace. In essence the error handling in the 3rd party API does something like this, catch ...
0
votes
1answer
61 views

Is there any reason not to allow negative numbers to be entered into a JSP field labeled for positive numbers?

Our application, a fairly complicated money ledger, has a JSP field for entering a certain type of money due, balanced by payments made towards that amount due. In the application, this field is ...
1
vote
2answers
32 views

Application model management questions

Consider the following type of Java / Spring web application, with an SQL database: there are multiple data entity types (about 100) with relations between them the entities are viewed, edited or ...
4
votes
4answers
344 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 ...
-2
votes
1answer
42 views

ClickHandler for button = strategy pattern? [closed]

If you provide a implementation of a ClickHandler interface to a button (defining some behaviour), is this the strategy design pattern?
1
vote
1answer
148 views

How to concurrently write data in Java without locking?

How to implement a multi-threaded program in which each thread needs to write/output some data (in any order of course) but without the locking overhead that is involved with files or a particular ...
4
votes
3answers
770 views

How to open a desktop application through browser without a Java applet?

We run a cloud-based medical software, and a very important part of the program is bridging to an imaging software straight from our website, passing information through command line arguments. We ...
0
votes
2answers
189 views

Check if a variable is equal to any of several values

I'm trying to check if an integer is equal to any of several values and don't want to do this: int d = 0; if(d == 3 || d == 8 || d == 1) { System.out.println("d is one of the special numbers!"); ...