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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11
votes
2answers
636 views

Java has the JVM, what does C have?

I know that C has a compiler but what determines execution performance? For example in an if else block, what if the code just had all ifs instead of if elses, what determines that all the ifs will ...
2
votes
2answers
219 views

When to use a SortedMap interface?

The rule in programming is to use the most general interface possible. But the difference between Map and SortedMap is more subtle. They compile to the same bytecode [I think] No additional safety ...
1
vote
2answers
118 views

Caveats of using String.hashCode() on a switch on java < 1.7

There are several cases when I want to switch over a String input. I decided for implementing something like: public Object doStuff(String param) { switch (param.hashCode()) { case 1234546: ...
1
vote
2answers
162 views

My value checker function needs to return both a boolean and a message

I have a value checking function, something much like a credit card number checking function, that is passed in a string, and needs to check that the value is of the right format. If it's the right ...
9
votes
7answers
2k views

Does Oracle reap economic benefits by maintaining Java? [closed]

It occurred to me that many programming languages such as Python and Javascript are maintained by non-profit foundations. I can see why a foundation would update a free programming language- in order ...
1
vote
2answers
109 views

Adding Logging to a pre-existing Program

I have a game that I have been writing in java as a hobby for a number of years. I have very sparse logging, just some simple output when something goes really wrong. It's about 25,000 lines of code. ...
4
votes
2answers
229 views

Exception versus return code in DAO pattern

After reading a lot about the abusive use of exceptions in Java and how you should let an exception bubble up through the different layers of an application, I've come to a point where I don't know ...
2
votes
1answer
90 views

Transactions and subresources with JAX-RS

I'm porting an existing application RESTful API to a Java web framework -- I don't actually care which -- but it's proving hard to get the basics right. The core of the problem appears to be getting ...
7
votes
2answers
265 views

Retry design for high volume

I have a Java system using ActiveMQ for messaging. And the system processes about 400 to 600 transactions a second and we have no issue when everything is running smoothly. The system also got to send ...
0
votes
1answer
80 views

Pattern for separating UI code from logic in Wicket

I'm using Apache Wicket for developing web apps, I have developed a few for the last year and it has been great; today I was looking at a few pages and most of them look like this: public class ...
1
vote
0answers
45 views

Enforce coding decision to include or exclude an Enum element in an EnumSet at compile time

I would like to enforce that the elements of a Java Enum are chosen or excluded from an EnumSet at compile time i.e. I am forced to make the decision to put it in the set or not whenever I create a ...
1
vote
2answers
123 views

Is it a good idea to require passwords in offline applications?

I am developing an application which can install extension modules (plugins, if you will) from APT-style repositories hosted elsewhere. The plugins need not be signed (although the downloads are ...
1
vote
2answers
175 views

Smells in exception handling: how to separate between public and internal exceptions?

During the development of a small web API, we decided to separate internal exceptions from public exceptions. Public exceptions are HTTP exceptions, that translate into HTTP responses with proper ...
1
vote
0answers
28 views

do my “dal” and “fileHandler” interfaces overlap?

I want my program to: 1) read some input lines from csv file 2) write the output lines to plain string file 3) read some input from the same file in (2) and compare it to some calculated data. I ...
1
vote
0answers
122 views

Optimal data structure for binary data/Java

I have several input formats mostly restricted to geotiff and some proprietary binary formats. I import them into my program and then need to export them into various other data formats (also binary) ...
0
votes
1answer
130 views

advantage of having multiple REST web services

I have a application designed using Spring REST service. the application has two REST projects: Web Core Web has html, JavaScript and Java classes (ajax calls this REST). These Java classes in ...
0
votes
2answers
72 views

Handling DomainExceptions using REST endpoint

Suppose I'm doing some DDD. Now, I have a microservice reflecting a bounded context/a part of a bounded context. Now, suppose there is a REST endpoint: '/somedomainmodel/someaction' My API user is ...
1
vote
0answers
98 views

How and where to make global function file in jsp sevlet web application

I am making a website in Servlet&JSP. I am looking for good way to make a specific function file from where I can call and declare my common functions. If I made a java file function. Java, so is ...
4
votes
1answer
202 views

What are the reasons for sealing a .jar and how would I verify that?

I have created a sealed jar, but I don't see difference compared to using a non-sealed one. What tests I can perform to verify the jar is sealed? What reason we could have to prefer using a sealed ...
0
votes
1answer
120 views

Possible way to make java class builder more abstract by using interface required keys

I'm looking for a more abstract pattern for builders that handles required fields without the need of writing a validator that checks if all requried fields are set. I like this builder. But is ...
0
votes
1answer
87 views

Is set of libraries called API only if it talks to a system/server?

I have read few articles about API. Can't find the reference now. In some of them, they define API as set of tools, routines and protocols which are helping programmer to build a software with use of ...
0
votes
1answer
84 views

best way to export binary data with additional text attributes to a stream

I would like to create a command line API in a Java application to export a binary blob to stdout. I would additionally like to export certain attributes about the blob, ideally in a non-binary ...
29
votes
8answers
4k views

Is throwing an exception an anti-pattern here?

I just had a discussion over a design choice after a code review. I wonder what your opinions are. There's this Preferences class, which is a bucket for key-value pairs. Null values are legal ...
2
votes
3answers
165 views

What is the difference between a variable and a parameter? [closed]

Its a conceptual question. But I would like to use the right term at the right place. That is why I would like to read some other views on this.
-4
votes
1answer
109 views

Why java has so many frameworks [closed]

why java has so many frameworks? why core java is not sufficient enough to solve the problem or develop anything? Even if core java is insufficient enough that we need frameworks,why there are ...
4
votes
1answer
107 views

How would I isolate changes to mutable state if I need to run two queries to get the final result?

I'm working on some code that takes search criteria from a Rest API and uses it to query a remote API to return results. As an exercise, I wanted to try to separate all state changes to one place, as ...
-1
votes
5answers
2k views

Why Java is a factor 2-3 slower than equivalent C++ program? [closed]

I know there is an opinion that programs written in Java and running under JVM as as fast as C++ programs, after introducing just-in-time (JIT). I see many cases when Java is terribly slow for simple ...
0
votes
2answers
108 views

How to write a new annotation that behaves precisely like an existing one?

Here is my use case. Suppose annotations did have inheritance and would automatically inherit the entire behaviour of the base class. Then I would do the following (note the two package statements): ...
0
votes
2answers
270 views

What is the rule for nested loop code?

I am new to programming and currently learning Java from Stanford free learning course. There was this assignment that I had trouble translating my algorithm into code. I feel like I have a ...
1
vote
1answer
82 views

Language support for (syntactic) delegation in Java

Composition over inheritance is an old trend or even accepted state of the art in object oriented programming. It would be even easier to use in Java, if there were language support for delegation. ...
17
votes
7answers
3k views

Why is instance creation the way it is?

I've learned C# over the course of the past six months or so and am now delving into Java. My question is about instance creation (in either language, really) and it's more of: I wonder why they did ...
1
vote
1answer
119 views

Open closed principle vs abstraction leaking (Java enums)

In Java, an enum is not a plain replacement for a number (like in C/C++), but a family of objects which can have properties. For instance public enum Order { NAME("Ordering by name"), ...
13
votes
4answers
885 views

“Use map instead of class to represent data” -Rich Hickey

In this video by Rich Hickey, the Clojure creator, he advises to use map to represent data instead of using a class to represent it, as done in Java. I don't understand how it can be better, since how ...
3
votes
2answers
378 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 ...
3
votes
1answer
218 views

Does the JVM's Garbage Collector clean the entire JVM HotSpot memory (C-Heap, Java Heap and Permanent Generation space) or just Java Heap?

I know that the JVM has some JVM HotSpot memory which is further divided into three areas: Java Heap Permanent Generation Space Native Heap (C-Heap) I know that Java has automatic garbage ...
3
votes
2answers
299 views

Do wildcards in Java generics restrict or increase flexibility?

I have read many sources about wildcards and Java generics. Even though I have seen many explanations and answers, none of them seems correct. The question is very simple: Do wilcards in Java ...
1
vote
1answer
224 views

Most efficient way of searching very large strings of text in java

I have a question that I have been thinking about recently but I am still not sure of the answer(s) so I would like a broader opinion. Imagine the scenario where text strings of up to lets say ...
23
votes
4answers
4k views

Why doesn't Java have optimization for tail-recursion at all?

From what I have read: The reason is because it is not easy to determine which method will actually be called as we have inheritance. However, why doesn't Java at least have tail-recursion ...
0
votes
3answers
411 views

Overriding equals() method in Java

Short question: Why does Java allow overriding equals(), why is it not final? I am reading Effective Java 2nd edition by Joshua Bloch. I am a bit baffled by the conclusion that There is no way to ...
1
vote
0answers
58 views

Multiple 1024x1024 texture pages or one 2048x2048 texture page?

I have a lot of textures around the size of 512x512, and the LibGDX texture packer can't find a way to put more than one of those on one page for some reason. So, I end up with fifteen or sixteen ...
1
vote
2answers
200 views

Why can we use the same name for local variable in different scopes?

I was wondering why is it possible that we can use the same name for local variable in different scopes? Like we can have two methods which both can have variable with the same name. What makes ...
2
votes
3answers
153 views

Java logging dependency for a low-level library

I inherited a lower-level open source Java network library. The library is intended to be used by higher-level application protocol libraries which are in turn used by application code. My library, ...
1
vote
4answers
407 views

Use JSON objects or POJOs in back end service?

I'm building a back end service for mobile clients. The requirement is that the mobile clients will pass me a token, I'll use that token to talk to other systems (behind the company firewall) in my ...
14
votes
4answers
1k views

How does one keep argument counts low and still keep third party dependencies separate?

I use a third party library. They pass me a POJO that, for our intents and purposes, is probably implemented like this: public class OurData { private String foo; private String bar; private ...
5
votes
2answers
463 views

When to fix something that is “wrong” but works fine

Short version: I wrote some code that is not done "the right way" because, when I wrote it, I didn't know how to do it. Now that I know how to do it "the right way", how do I decide how to fix it? ...
4
votes
2answers
334 views

Is it a good practice to burn business logic into Enums?

Let's have a simplified business logic like this: public enum BusinessLogic { STAGE_ONE(true, false, false), STAGE_TWO(true, true, false), STAGE_THREE(false, false, true); private final ...
1
vote
5answers
269 views

Should abstract classes be used to prevent instantiation

Is preventing the instantiation of a class a valid reason to make it abstract? For example, if I have a class called Gauge which has subclasses HeadingIndicator and AirSpeedIndicator, is it a good ...
-1
votes
1answer
108 views

How to identify http requests made from a closed-source java app?

I am an avid Go player and play on the Kiseido Go Server. I would like to write an open source client for this, but the KGS protocol is a well-kept secret. Is there any way to catch the http ...
0
votes
3answers
262 views

Why Double.parseDouble(“ABC”) not returns Double.NaN?

This code: Double.parseDouble("ABC") throws a NumberFormatException. Why is it wrong to expect a Double.NaN (NaN is literally Not-A-Number). A working example is this: public static void ...
6
votes
2answers
346 views

Small code, big test

I have this code in a controller of an MVC implementation: public void execute() { try { String path = userSelectsFile(); if ( path == null ) return; //Just returns ...