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Questions tagged [java]

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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202 votes
14 answers
141k views

When are Getters and Setters Justified?

Getters and setters are often criticized as being not proper OO. On the other hand, most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to ...
283 votes
6 answers
167k views

Choosing between Single or multiple projects in a git repository?

In a git environment, where we have modularized most projects, we're facing the one project per repository or multiple projects per repository design issue. Let's consider a modularized project: ...
Johan Sjöberg's user avatar
300 votes
14 answers
462k views

How do you unit test private methods?

I am working on a java project. I am new to unit testing. What is the best way to unit test private methods in java classes?
Vinoth Kumar C M's user avatar
35 votes
6 answers
9k views

Should I extract specific functionality into a function and why?

I have a large method which does 3 tasks, each of them can be extracted into a separate function. If I'll make an additional functions for each of that tasks, will it make my code better or worse and ...
dhblah's user avatar
  • 1,381
71 votes
8 answers
22k views

How do you encode Algebraic Data Types in a C#- or Java-like language?

There are some problems which are easily solved by Algebraic Data Types, for example a List type can be very succinctly expressed as: data ConsList a = Empty | ConsCell a (ConsList a) consmap f ...
Jörg W Mittag's user avatar
24 votes
4 answers
12k views

Make methods that do not depend on instance fields, static?

Recently I started programming in Groovy for a integration testing framework, for a Java project. I use Intellij IDEA with Groovy plug-in and I am surprised to see as a warning for all the methods ...
Random42's user avatar
  • 10.5k
27 votes
4 answers
9k views

Legitimate "real work" in a constructor?

I am working on a design, but keep hitting a roadblock. I have a particular class (ModelDef) that is essentially the owner of a complex node tree built by parsing an XML schema (think DOM). I want to ...
Gurtz's user avatar
  • 389
110 votes
12 answers
21k views

I've been told that Exceptions should only be used in exceptional cases. How do I know if my case is exceptional?

My specific case here is that the user can pass in a string into the application, the application parses it and assigns it to structured objects. Sometimes the user may type in something invalid. ...
Daniel Kaplan's user avatar
148 votes
6 answers
115k views

What is the point of having every service class have an interface? [duplicate]

At the company I work at, every service class has a corresponding interface. Is this necessary? Notes: Most of these interfaces are only used by a single class We are not creating any sort of ...
Bob Roberts's user avatar
  • 1,807
10 votes
1 answer
14k views

Testing private methods as protected

I was reading this answer about testing private methods and it mentioned several possibilities: extract methods as public to another class make them public separate the env of test and production ...
sam's user avatar
  • 211
22 votes
6 answers
13k views

Efficient try / catch block usage?

Should catch blocks be used for writing logic i.e. handle flow control etc? Or just for throwing exceptions? Does it effect efficiency or maintainability of code? What are the side effects (if there ...
HashimR's user avatar
  • 323
16 votes
3 answers
28k 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 ...
dwjohnston's user avatar
  • 2,563
88 votes
11 answers
13k views

Did the developers of Java consciously abandon RAII?

As a long-time C# programmer, I have recently come to learn more about the advantages of Resource Acquisition Is Initialization (RAII). In particular, I have discovered that the C# idiom: using (var ...
JoelFan's user avatar
  • 7,091
0 votes
2 answers
5k views

What other reasons are there to write interfaces rather than abstract classes? [duplicate]

Possible Duplicate: When to use abstract classes instead of interfaces and extension methods in C#? When I read and looked at codes using Abstract classes, I was able to justify it because it ...
javastudent's user avatar
135 votes
5 answers
83k views

In Java, should I use "final" for parameters and locals even when I don't have to?

Java allows marking variables (fields / locals / parameters) as final, to prevent re-assigning into them. I find it very useful with fields, as it helps me quickly see whether some attributes - or an ...
Oak's user avatar
  • 5,265
22 votes
11 answers
100k views

Best way to handle nulls in Java? [closed]

I have some code that is failing because of NullPointerException. A method is being called on the object where the object does not exist. However, this led me to think about the best way to fix this....
Shaun's user avatar
  • 407
22 votes
10 answers
9k views

Is it a really required skill to program without API documentation? [closed]

I barely passed my Java programming exam today. I had to answer some general questions about threading which I did well and to write a little threaded program which was worse. I had to connect my ...
bancer's user avatar
  • 361
17 votes
4 answers
7k views

Single method with many parameters vs many methods that must be called in order

I have some raw data I need to do many things to (shift it, rotate it, scale it along certain axis, rotate it to a final position) and I am not sure what the best way to do this to maintain code ...
tomsrobots's user avatar
11 votes
5 answers
13k views

How should I handle exception that *should* never be thrown? [duplicate]

What is the best way to handle errors that shouldn't ever happen? My current way to do this is to throw an exception if the 'thing that shouldn't happen' does happen, like so: /* * Restoring from a ...
elimirks's user avatar
  • 275
276 votes
14 answers
124k views

Should we avoid object creation in Java?

I was told by a colleague that in Java object creation is the most expensive operation you could perform. So I can only conclude to create as few objects as possible. This seems somewhat to defeat ...
Slamice's user avatar
  • 2,657
107 votes
4 answers
72k views

How is a Java reference different from a C pointer?

C has pointers and Java has what is called references. They have some things in common in the sense that they all point to something. I know that pointers in C store the addresses they point to. Do ...
Gnijuohz's user avatar
  • 2,065
59 votes
9 answers
48k views

Should the methods of a class call its own getters and setters?

Where I work I see lots of classes that do things like this: public class ClassThatCallsItsOwnGettersAndSetters { private String field; public String getField() { return field; }...
Daniel Kaplan's user avatar
31 votes
5 answers
36k views

What is the difference between all-static-methods and applying a singleton pattern? [duplicate]

I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton ...
shahensha's user avatar
  • 599
29 votes
6 answers
12k views

Is there a canonical book for learning Java as an experienced developer? [closed]

I have been a .NET developer now for about the past 5/6 years give or take. I have never done any professional Java development and the last time I really touched it was probably back in college. I ...
Nodey The Node Guy's user avatar
262 votes
7 answers
299k views

What does the Spring framework do? Should I use it? Why or why not?

So, I'm starting a brand-new project in Java, and am considering using Spring. Why am I considering Spring? Because lots of people tell me I should use Spring! Seriously, any time I've tried to get ...
sangfroid's user avatar
  • 3,239
57 votes
8 answers
9k views

Why a static main method in Java and C#, rather than a constructor?

I’m Looking for a definitive answer from a primary or secondary source for why (notably) Java and C# decided to have a static method as their entry point, rather than representing an application ...
Konrad Rudolph's user avatar
38 votes
3 answers
75k views

When to use a Singleton and when to use a static class [duplicate]

I've searched about this here and on StackOverflow and found some differences between the two. But I'm still not sure in what cases one would prefer a Singleton, and in what cases one would choose to ...
Aviv Cohn's user avatar
  • 21.4k
35 votes
5 answers
9k views

How to deal with checked exceptions that cannot ever be thrown

Example: foobar = new InputStreamReader(p.getInputStream(), "ISO-8859-1"); Since the encoding is hardcoded and correct, the constructor will never throw the UnsupportedEncodingException declared in ...
user281377's user avatar
  • 28.4k
17 votes
2 answers
64k views

Why shouldn't I be using public variables in my Java class? [duplicate]

In school, I've been told many times to stop using public for my variables. I haven't asked why yet. This question: Are Java's public fields just a tragic historical design flaw at this point? ...
Saturn's user avatar
  • 3,907
222 votes
6 answers
58k views

What exactly makes the Haskell type system so revered (vs say, Java)?

I'm starting to learn Haskell. I'm very new to it, and I am just reading through a couple of the online books to get my head around its basic constructs. One of the 'memes' that people familiar with ...
phatmanace's user avatar
  • 2,475
179 votes
6 answers
298k views

What is the point of using DTO (Data Transfer Objects)?

What is the point of using DTO and is it an out dated concept? I use POJOs in the view layer to transfer and persist data. Can these POJOs be considered as an alternative to DTOs?
Vinoth Kumar C M's user avatar
170 votes
10 answers
24k views

Mono is frequently used to say "Yes, .NET is cross-platform". How valid is that claim? [closed]

In What would you choose for your project between .NET and Java at this point in time? I say that I would consider the "Will you always deploy to Windows?" the single most important technical decision ...
user avatar
147 votes
15 answers
31k views

Why did memory-managed languages like Java, Javascript, and C# retain the `new` keyword?

The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new ...
103 votes
6 answers
153k views

Stack and Heap memory in Java

As I understand, in Java, stack memory holds primitives and method invocations and heap memory is used to store objects. Suppose I have a class class A { int a ; String b; //...
Vinoth Kumar C M's user avatar
95 votes
17 answers
21k views

Is imposing the same code format for all developers a good idea?

We are considering to impose a single standard code format in our project (auto format with save actions in Eclipse). The reason is that currently there is a big difference in the code formats used by ...
86 votes
11 answers
34k views

Why is String immutable in Java?

I couldn't understand the reason of it. I always use String class like other developers, but when I modify the value of it, new instance of String created. What might be the reason of immutability ...
yfklon's user avatar
  • 1,772
78 votes
4 answers
54k views

Dependency Injection: Field Injection vs Constructor Injection?

I know this is a hot debate and the opinions tend to change over time as to the best approach practice. I used to use exclusively field injection for my classes, until I started reading up on ...
Eric B.'s user avatar
  • 1,249
63 votes
5 answers
68k views

When to use primitive vs class in Java?

I see that Java has Boolean (class) vs boolean (primitive). Likewise, there's an Integer (class) vs int (primitive). What's the best practice on when to use the primitive version vs the class? ...
Casey Patton's user avatar
  • 5,231
59 votes
11 answers
14k views

Why does C++ have 'undefined behaviour' (UB) and other languages like C# or Java don't?

This Stack Overflow post lists a fairly comprehensive list of situations where the C/C++ language specification declares as to be 'undefined behaviour'. However, I want to understand why other modern ...
Sisir's user avatar
  • 858
56 votes
3 answers
72k views

Which is a better practice - helper methods as instance or static?

This question is subjective but I was just curious how most programmers approach this. The sample below is in pseudo-C# but this should apply to Java, C++, and other OOP languages as well. Anyway, ...
Ilian's user avatar
  • 663
43 votes
3 answers
63k views

What is message passing in OO?

I've been studying OO programming, primarily in C++, C# and Java. I thought I had a good grasp on it with my understanding of encapsulation, inheritance and polymorphism. One frequently referenced ...
Tom's user avatar
  • 852
31 votes
9 answers
30k views

Are init() methods a code smell?

Is there any purpose for declaring an init() method for a type? I'm not asking whether we should prefer init() over a constructor or how to avoid declaring init(). I'm asking if there is any ...
Dioxin's user avatar
  • 953
21 votes
4 answers
4k views

"Too object-oriented"

I come from a strong OO background, and I have recently started working in an organization which, although the code is written in Java, has a lot less emphasis on good OO design than what I am used to....
ThuneGrill's user avatar
18 votes
4 answers
19k views

Why define a Java object using interface (e.g. Map) rather than implementation (HashMap)

In most Java code, I see people declare Java objects like this: Map<String, String> hashMap = new HashMap<>(); List<String> list = new ArrayList<>(); instead of: HashMap<...
Suman's user avatar
  • 453
14 votes
5 answers
3k views

Is Ant still in the "mainstream" for Java builds?

We have been slowly replacing batch command files (windows .bat) which were simply jarring up the classes compiled in the developers IDE, with more comprehensive Ant builds (i.e. get from CVS, clean ...
Sam Goldberg's user avatar
  • 1,004
12 votes
3 answers
36k views

Why is BigDecimal the best data type for currency? [duplicate]

I was reading this question and the accepted answer says that BigDecimal is the best type for representing currency values. I've also seen several other questions support the use of big decimal. Why ...
MxLDevs's user avatar
  • 789
3 votes
5 answers
6k views

The need for adding an interface to every class [duplicate]

My coworker and I are arguing very hard about this topic. He's thinking that every single class should have an Interface that the class implements (also Single-Implementations). He uses this design ...
DmiN's user avatar
  • 161
197 votes
40 answers
20k views

My Dad is impatient with the pace of my learning to program. What do I do? [closed]

So my Dad bought me 5 books on programming (C++, Java, PHP, Javascript, Android) about a month ago. He's an architect and he knows NOTHING about programming. He bought me them because I told him ...
135 votes
4 answers
125k views

Excessive use "final" keyword in Java [duplicate]

While I understand what the final keyword is used for in the context of classes and methods as well as the intent of its use for in regards to variables; however, the project I just started working on ...
rjzii's user avatar
  • 11.3k
120 votes
11 answers
55k views

What backs up the claim that C++ can be faster than a JVM or CLR with JIT? [closed]

A reoccurring theme on SE I've noticed in many questions is the ongoing argument that C++ is faster and/or more efficient than higher level languages like Java. The counter-argument is that modern JVM ...
Anonymous's user avatar
  • 3,556

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