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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java.util.HashMap lock on actual HashMap object compare to lock on object that encapsulate the HashMap

The below Javadoc is an snippet of HashMap documentation. Why authors would emphasize on putting a lock on the object that encapsulate a HashMap? Lock on the actual HashMap Object makes for sense. ...
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1answer
201 views

How to fix poorly designed software? [closed]

I am working on large project solo as a hobby, and I made a mistake in the very beginning: I jumped right into programming without giving a second though to design. Now I am nearly 6 months in and ...
2
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1answer
356 views

How to avoid overhead while still implementing null object pattern?

I am implementing a binary search tree in java. Inside the BST class I have a protected class Node (in case I want to extend to an AVL tree). The code is below. I had a problem, both conceptually and ...
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3answers
190 views

Best way to find whether a collection does or does not contain an element with a specific desired quality

It seems to be a very common thing to have to tell whether some list or set contains at least one object matching a given condition, yet my prior searching and reading have never found a satisfactory ...
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3answers
240 views

Is it appropriate to remove redundant code explicitly assigning the default values?

Sometimes while I'm editing something I see some useless code added by other developers, probably due to habit. Editing this code will not make any difference, so is it appropriate? In my specific ...
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2answers
2k views

Why are there no function pointers in Java? [closed]

Lately I started studying about different interesting concepts that exist in languages other than Java. Since the only language I've ever programmed with is Java, a lot of these concepts are very new ...
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5answers
2k views

Why is there no deterministic object destruction in Java? [duplicate]

I understand and enjoy the benefits of the Garbage Collection in Java. However I don't understand why there is no way in Java to explicitly (and quickly) destroy an object. Surely this could be useful ...
2
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1answer
166 views

Separate Action from Assertion in Unit Tests

Setup Many years ago I took to a style of unit testing that I have come to like a lot. In short, it uses a base class to separate out the Arrangement, Action and Assertion of the test into separate ...
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3answers
326 views

If I unite many web apps into one, will I save resources?

I'm comparing 2 different approaches of J2EE application architecture: Divide independent parts as modules of one big web app. Divide independent parts as different web apps running on same server. ...
3
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2answers
440 views

Retried Operation with generic Exception

I am looking for a way to get the logic of retrying an operation in a single method while keeping the exception types of the operation. I.e., the implementation to retry an operation could look like ...
1
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1answer
351 views

Should we push for more JavaScript on the JVM, alongside Java and Scala? Or, if not, why? [closed]

With JavaScript becoming one of the most widely used languages around, I began asking myself why people do not find ways to use it extensively on the JVM. As a programmer who spends half day writing ...
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2answers
366 views

When should you use Local Classes in Java?

I learned about local classes on the Oracle Java Tutorial page. Not nested classes. I don't see myself using local classes. It makes the code look messy and you can easily do what local classes do ...
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1answer
291 views

How to design the relation between a Game and a Player in a game?

I am currently attempting to make a Trading Card Game and I have got a whole array of features working already, yet I am stuck now at the portion where one player can attacker another player (more ...
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2answers
406 views

A 'task' system which has an ending, to get ready for next task

I want to make a system, so that there are certain tasks. For example, let's talk about a game. I want to make it so there are 100+ tasks doing different things, but when the player's magic level is ...
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4answers
571 views

Why is Java not 'pure' OOP? [duplicate]

Java is designed in a very OO approach, and somewhat even 'forces' programmers to program within the OO paradigm (which can be considered good or bad, a matter of opinion). However while almost ...
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1answer
325 views

Type Safety of Spray.io

Yesterday I read a tweet disparaging Jersey with JAX-RS due to run-time errors. Spray.io was mentioned in the tweet: Not even 5 minutes using Jersey / JAX-RS and already a runtime error due to a ...
2
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1answer
7k views

Calling static method from instance of class

As a developer I am fan of static methods. Recently I come across difference between OOP languages about this static methods. All OOP language use static method to access any method without ...
4
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1answer
261 views

Managing resource paths in source code

I suspect this is something that many of you have dealt with, and I'm certain there's articles on how to do it, but I can't seem to find them. My problem is that my various constant classes in Java ...
2
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2answers
333 views

Benefits of Java in education? [closed]

I hope this isn't too off-topic and/or opinion based. I'm looking for examples and reasons why Java is an acceptable language for education purposes. Here's why: I learned programming on my own in C ...
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2answers
185 views

Is using interfaces on internal code a good idea? [duplicate]

I'm working on a set of automated tests that we use internally at work. Lately, we've been designing classes that implement interfaces in addition to inheritance. As I understand it, interfaces in ...
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2answers
379 views

How other thread can show the incremented value unless the 1st thread reaches the return statement?

My code is given below. In the for loop I am getting unexpected output i.e. before completing the execution of for loop by 1st thread the 2nd thread comes in for loop and shows incremented value. ...
5
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4answers
1k views

Why do arrays in Java not override equals()?

I was working with a HashSet the other day, which has this written in the spec: [add()] adds the specified element e to this set if this set contains no element e2 such that (e==null ? e2==null : ...
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1answer
301 views

How to migrate an XML serialization framework in Java in a tightly coupled system?

I work for a company that uses XML for storing a bunch of serialized Java classes. The framework we use is Apache Betwixt (abandonded in 2008) and it's kind of pain to maintain and extend (it seemed ...
2
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1answer
1k views

Passing multiple errors back from service layer

I am using Spring for a web application. To validate a user's input in a form such as for creating a Person entity I user JSR 303 validation to check for not null/empty or valid patterns etc.. Some ...
7
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2answers
377 views

How to hide AOP implementation dependency without breaking encapsulation?

I have the concept of a SlowLoading thing: public interface SlowLoading { boolean hasLoaded(); } I also have a component MyComponent: public interface myComponent{ void doSomething(); } My ...
2
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2answers
11k views

Generating PDF files using individual template components

EDIT: Updated flow diagram to better explain the (likely unnecessary) complexity of what I'm doing. We at the company I work for are attempting to create complex PDF files using Java iText (the ...
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2answers
205 views

When one thread out of four is executing first line in run() then at the same time what will remaining three threads do?

I have four thread instances and they are executing run() code given below: public void run (){ System.out.println("1st line :"+Thread.CurrentThread().getName()); System.out.println("2nd line ...
3
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1answer
460 views

How to present domain model exceptions thrown through validation

In domain model of my web application I've an entity Foo which can be created only by a pojo FooBean: Foo.newInstance(FooBean fooBean) (Might have been better a Builder-pattern.) In the factory ...
4
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2answers
3k views

Is there any reason not to use Optional as a method argument in the case where you know the argument is something that may or may not be needed?

With Java 8, I've seen more and more articles about the use of Option/Optional. I understand what they trying to represent, and I see many examples of them being used as returns. However what I don't ...
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2answers
378 views

From a DDD perspective is a report generating service a domain service or an infrastructure service?

Let assume we have the following service whose responsibility is to generate Excel reports: class ExcelReportService{ public String generateReport(String fileFormatFilePath, ResultSet data){ ...
2
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2answers
1k views

static set and non-static get method

I've the following Interface. public interface ValueInterface { long getValue(); } And the class: public class ValueCreator implements ValueInterface { private static long value = 0; ...
2
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1answer
328 views

Why does Java support brackets behind variables and even behind method signatures? [closed]

Java allows this: class X{ int i,j[]; // j is an array, i is not } and even worse, it allows this: class X{ int foo(String bar)[][][] // foo actually returns int[][][] { return null; } ...
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2answers
2k views

Should I use initializer blocks in Java?

I recently came across a Java construct I have never seen before and was wondering whether I should use it. It seems to be called initializer blocks. public class Test { public Test() { /* first ...
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2answers
222 views

How to debug weak references? [closed]

How can I test (what tools do I use) if my reference graph is correct and if objects are released at appropriate times (and there are no memory leaks)? In my case I'm using Java, but answers related ...
16
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3answers
12k views

Why prefer non-static inner classes over static ones?

This question is about whether to make an inner class in Java static or not. I searched around here and on StackOverflow, but couldn't really find any questions regarding the design implications of ...
1
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1answer
1k views

Why does storm not supply a mechanism for supplying topology necessary dependent jars other than the fat jar?

Following is a question that I had posted at the incubator-storm-user mailing list (verbatim). I had decided to open up the question here as well, because it also contains a conceptual side to it, ...
2
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1answer
246 views

What's the right OO way to create a counter/inventory class that works for both differentiated and undifferentiated countables?

You are writing a videogame about trading beans. Red beans, black beans, pinto beans, you name it. As everybody knows all beans are the same. You write the "Inventory" class for a trader in that ...
2
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1answer
1k views

Accessing a remote server from desktop application

Web applications (.jsp / Java) have the advantage that they can be run from any client browser by putting a single URL into the address bar, and off you go. However, the average web application is ...
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4answers
2k views

Why is there no 'subclasses-only' access modifier in Java?

In Java, there are four available access modifiers for methods: public - any class can use this method. protected - classes in the same package and subclasses in any package can use this method. ...
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3answers
440 views

Wrapping a map with instance or static method

I have a java.util.Map<String, Object> object which different types of values in it. I don't want to cast whereever I do a get operation over this. To do this, I created different classes ...
1
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1answer
539 views

Serpent Algorithm thats implement Cipher

How must i change the Standard Implemplementation of the Serpent Algorithm that i can use it with the javax.crypto.CipherInputStream or javax.crypto.CipherOutputStream? I must implement/extends the ...
0
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2answers
1k views

.properties files in regular src folder okay? [closed]

I work on a Java project with a suggested structure (separate src folders for java files and resource files). After moving the message / text related properties files to that folder, the externalize ...
2
votes
3answers
630 views

Where should I put bindings for dependency injection?

I'm new to dependency injection and though I've really liked it so far, I'm not sure where bindings should go. I'm using Guice in Java, so some of what I say might be specific to just Guice. As I see ...
8
votes
3answers
513 views

Object Identity and Mutability

I was reading a proposal for value types in Java, and I came across this sentence: "Object identity serves only to support mutability, where an object’s state can be mutated but remains the same ...
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2answers
473 views

How to set up something like an integration server that measures the quality of code and reject the code if the score is below a certain number?

Even if I don't like enforcing people to do things (and I believe that it may decline the productivity and cause anger), I really want to enforce good coding style. Is there a way to set up ...
0
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1answer
441 views

Making the server request with high priority

I need to connect to a server and do manipulation with respect to HTTP GET and POST for my application and the server is generally used to handle multiple users with heavy load and many users might be ...
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4answers
735 views

Alternatives to null values and option-like types

Related to this question i want to know if there is a concise way to eleminate null values out of code in general or if there is not. E.g. imagine a class that represents a user with birthday as ...
5
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1answer
809 views

Naming test methods in Java [closed]

Over at codereview a comment hinted that using snake_case to name test methods is a good idea. This contradicted my views and I did some research and there seem to be a lot of examples that actually ...
2
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1answer
344 views

Should we encapsulate everything in a try{} block in a Try object?

Why can't I make a class for a Try including what I try and then run that in the try {} block? Why is it impractical? class DBConnectTry extends Try { TryResponse response[] attempt(TryObject ...
12
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6answers
2k views

alternatives to nested try-catches for fallbacks

I have a situation where I am trying to retrieve an object. If the lookup fails I have several fallbacks in place, each of which may fail. So the code looks like: try { return ...