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
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
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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
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1answer
609 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
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1answer
705 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
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3answers
201 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
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1answer
268 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
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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
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2answers
988 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
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1answer
456 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
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6answers
4k 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
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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 "...
42
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7answers
4k views

Why is the finalize method included in Java?

According to this post, we should never rely on the finalize method to be called. So why did Java include it in the programming language at all? It seems like a terrible decision to include in any ...
1
vote
1answer
123 views

Implement RPC via SIP

Look at the following use case. I have a client (Java) application, which wants to get/set the state of another, remote application (C). The communication between them is done via SIP, which is run ...
28
votes
10answers
4k views

Is template “metaprogramming” in Java a good idea?

There is a source file in a rather large project with several functions that are extremely performance-sensitive (called millions of times per second). In fact, the previous maintainer decided to ...
0
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3answers
459 views

Why do APIs generally consist of interfaces? [duplicate]

I am starting out in Java API design and in reading existing code bases, I have found that most APIs consist of interfaces only with their implementations bundled in a different package. Having read ...
35
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8answers
10k views

Is it an antipattern, modifying an incoming parameter? [closed]

I am programming in Java, and I always make converters sort of like this: public OtherObject MyObject2OtherObject(MyObject mo){ ... Do the conversion return otherObject; } At the new ...
3
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4answers
629 views

Is it possible to have a single code base for a desktop GUI and a web application?

The required user interface is fairly simple; basically, two tables that "interact with each other", e.g. certain rows in one table get highlighted when a row in the other is clicked, plus maybe a ...
3
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2answers
467 views

Is the Java Integer cache a realization of the object pool pattern?

One of the best-known examples of a full-fledged object pool is the JDBC connection pool. Main reasons: objects in the pool are expensive to create and relate with external resources each object in ...
2
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3answers
473 views

Transitioning from Java & C to C++

I learned Java and I'm pretty competent programming in it. I also learned C recently. I looked at a comparison between Java and C++ and I like C++'s features like operator overloading and its speed. ...
0
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1answer
448 views

How can I use guice to replace code dependent on service locator implementation?

Consider I have a service called FileSystem, and that this FileSystem is used by various classes throughout the application. Typically, the service is acquired via some static class method ...
3
votes
1answer
161 views

Defining a random “safe” path for a game character

I am writing a game in Java and it can be likened to the recently popular game "Flappy Bird" in the sense that the character moves up and down and the users touch and must avoid the obstacles. The ...
1
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4answers
706 views

How to ideally calculate profit margin with zero sales

How do you handle the following scenario without null? You have this problem (In Java): BigDecimal sales = ...; BigDecimal cost = ...; BigDecimal profit = sales.subtract(cost); // Profit Margin = ...
0
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1answer
150 views

Broadcast receiver Or Services

I am creating an "Alarm Clock" app in Android. I learned that we can implement OnReciever() method and write those things which we want the alarm to do after an intent is fired. But I have now come ...
0
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1answer
1k views

Complexity of ArrayList of LinkedHashSet

I get input strings from the console like this: while ((currentLine = bufferedReader.readLine()) != null ) { StringTokenizer string = new StringTokenizer(currentLine, " "); while (string....
0
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1answer
670 views

problem on calculating Big O complexity

i have this function on which i have to calculate the time complexity with the Big O notation: public void print(ArrayList<String> operations, ArrayList<LinkedHashSet<String>> ...
0
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3answers
727 views

How to get an image or rectangle to detect collision with another image

Can someone please explain to me how to detect collision with another image? The tutorial I was watching explained how to detect if a collision occurs between two rectangles but I would like to use ...
2
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1answer
235 views

Working with a large, messy object [duplicate]

I have been handed a very cluttered, "One Ring" object (one object to rule them all). The OR class has 40 fields. These fields map to 16 different objects (the OR has all the fields from the 16 ...
45
votes
6answers
14k views

Why was C# made with “new” and “virtual+override” keywords unlike Java?

In Java there are no virtual, new, override keywords for method definition. So the working of a method is easy to understand. Cause if DerivedClass extends BaseClass and has a method with same name ...
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1answer
3k views

What is the best way to get a method name in runtime?

Here is a little background of my problem: I implemented a singleton logger class which is being called from several projects. I want to log the name of the class as well as the name of the method ...
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2answers
1k views

calculate complexity of LinkedHashSet

I have an ArrayList<LinkedHashSet<String>> setOfStrings for example this arraylist internally is composed like: positionX[hello,car,three,hotel,beach] positionY[.....] ... I want to ...
0
votes
2answers
96 views

Rectangle class java.lang.Object

Can someone please explain to me the difference or benefits rather to using the rectangle class ex. Rectangle r1 = new Rectangle(x,y,w,h); versus the graphics class drawRec method? g.drawRec(x,y,...
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1answer
233 views

Swing component name suggestion for a specific interface [closed]

As a university project, I have to replicate Raptor. A flowchart interpreter. The interface looks like this But as I am not a experienced swing developer, I don't have much idea about which swing ...
2
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2answers
364 views

Is it better to draw my own graphics or import images?

I am about to start a Tetris clone using Java as my programming language. While I was designing how it'd be done, I've stumbled upon this question: What would be better, if any difference at all, ...
7
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6answers
5k views

How to avoid downcasting?

My question is about a special case of the super class Animal. My Animal can moveForward() and eat(). Seal extends Animal. Dog extends Animal. And there's a special creature that also extends ...
0
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1answer
274 views

Sortable listview using SQLite [closed]

I'm implementing a sortable listview using bauerca's library here. This works, but now I need to define some things where I need some help. This is the functionality of my app_ I can create up to 5 ...
6
votes
4answers
7k views

Is it safe to convert Windows file paths to Unix file paths with a simple replace?

So for example say I had it so that all of my files will be transferred from a windows machine to a unix machine as such: C:\test\myFile.txt to {somewhere}/test/myFile.txt (drive letter is irrelevant ...
8
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4answers
668 views

What complexity do DI frameworks add?

The currently most upvoted answer to a very recent question states that DI containers are an "enterprise software" pattern, used when the object graph is very large and complex. I suspect that 95% ...
5
votes
2answers
463 views

I don't know how to understand the Wildcard type in Java

I am reading the Core Java (9th edition) by Cay S. Horstmann and Gary Cornell. After making an effort, I cannot still understand the ? super Manager. Here are some materials relating to this question. ...
1
vote
1answer
108 views

Reference wind directions to texture space?

I have a 2D array filled with a simple class: class Tile { boolean N,E,S,W; } I also have a tilesheet representing all possible outcomes except all false (12 + crossroad). Now i need to ...
2
votes
2answers
3k views

Where to start when designing an application that allows plugins [closed]

I'm building an application, and I'm thinking long-term I would like to be able to allow plugin support. The application I'm creating is a Java based application. How could I allow plugins using a ...
0
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1answer
220 views

Why/how does Java use a controlled mechanism to pause threads for GC?

I know that Java uses a controlled mechanism to allow threads to be paused. If I understood correctly, they put a read from a protected page at the end of e.g. loops, and change the protection of that ...
20
votes
7answers
5k views

Is there a more intelligent way to do this besides a long chain of if statements or switch?

I'm implementing an IRC bot that receives a message and I'm checking that message to determine which functions to call. Is there a more clever way of doing this? It seems like it'd quickly get out of ...
15
votes
2answers
7k views

Can someone explain in simple terms what is the disruptor pattern?

I would like if you could explain to me in a simple way how does the disruptor patter work. This concept has been elusive to me as of know. Perhaps with your help I could comprehend it.
0
votes
1answer
451 views

Object Oriented Design of a Small Java Game

This is the problem i am dealing with. I have to make a simple game of NIM. I am learning java using a book so far i have only coded programs that deal with 2 classes. This program would have about 4 ...
0
votes
1answer
530 views

How can I write byte[] to socket outputstream and specify the end of file?

I've googled 2 days straight and I can't find how to do this. I have an open stream between client and server, and client will send a JSON string (encrypted to bytes) to the server each 3 to 5 seconds....
2
votes
2answers
293 views

blurry lines between web application context layer, service layer and data access layer in spring

I'll admit I'm a spring newbie, but you can correct me if I'm wrong, this one liner looks kinda fishy in a best practices sort of way: @RepositoryRestResource(collectionResourceRel="people"...) ...
5
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2answers
252 views

Can decoupling hurt maintainability in certain situations?

Can the fact that the business logic is mapped to interfaces instead of implementations actually hinder the maintenance of the application in certain situations? A naive example with the Java's ...
0
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2answers
435 views

Java best practice Interface - subclasses and constants

In the case where a couple of classes implements an interface, and those classes have a couple of constants in common (but no functions), were should I put this constant ? I've had this problem a ...
2
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4answers
5k views

Regex to String generation

Let's say that we have a regex and an index i. If we suppose that the set of strings that match our regex are sorted in a lexicographical order, how could we get the i element of this list? Edit : I ...