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
votes
2answers
61 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 ...
-2
votes
0answers
7 views

How do I solve this java problem? [on hold]

I cant solve this problem which is given by AIDE ANDROID APP Please tell me the answer(because i am a beginner) I know it is simple but i am confused with that "mean" error please help me! Q- Now use ...
0
votes
0answers
14 views

Shadowing vs Inner class's access only to final variables

In Java : Shadowing allows us to modify any variable with same name in an inner block but how is it possible when we have access only to final variables in an inner class?
0
votes
0answers
15 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 ...
1
vote
3answers
136 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], ...
-1
votes
0answers
31 views

Which patterns to apply for “User Manager” [on hold]

I developing a social application and I neeed to create a User Manager that is responsible for managing certain types of user. A user who enters in to the system will be a new user or an existing ...
43
votes
7answers
8k views

How to deal with static utility classes when designing for testability

We are trying to design our system to be testable and in most parts developed using TDD. Currently we are trying to solve the following problem: In various places it is necessary for us to use static ...
50
votes
7answers
8k 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 ...
4
votes
1answer
369 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 ...
0
votes
0answers
22 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 ...
-1
votes
0answers
19 views

Weird Override and implementation [migrated]

I am currently programming an android app, but I have a problem. I want to use GreenDroid for my project but while compiling the compliler give me an error : The return type is incompatible with ...
5
votes
2answers
346 views

Is it possible to use the Android layout system in a desktop java application?

I am lazy, thus, if possible, I would like to only have to design and program a UI once. If I want to create an App for Android and as a basic Java desktop application, is there a way to reuse the UI ...
1
vote
1answer
104 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 ...
-3
votes
0answers
21 views

How to launch browser from Java WS and log on page by SSO?

I have an Java Web Start application which communicate with J2EE server application (JBoss). User is logging in (login & password) and after that doing some operations. Now I would like to add a ...
0
votes
0answers
22 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 ...
4
votes
5answers
429 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 ...
-2
votes
1answer
75 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
3answers
121 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
23 views

Spring-Quartz scheduler throw NoSuchMethodException [on hold]

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
152 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
52 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
48 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
189 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
181 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 ...
-6
votes
0answers
61 views

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

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
649 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
152 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
164 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 [on hold]

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
88 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
3k 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
1answer
63 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 ...
1
vote
0answers
36 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
7answers
8k 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
374 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 ...
0
votes
0answers
48 views

How to ace online/whiteboard coding interview [closed]

I am a fairly experienced Java developer(12 years), and if I have to believe my reviews, I exceed expectations almost every year. After 5 years in my current workplace, I recently started looking ...
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
36 views

Java: Weighted Selection help [on hold]

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
131 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
231 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
0answers
30 views

Toogle Button is not Working properly on wrong password [closed]

I'm trying to Enable/Disable Bluetooth on Toggle Button and Also, there is a additional functionality and that is asking password on enable/disable. Toggle Button is taking Default state of Bluetooth ...
2
votes
1answer
120 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
87 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 ...