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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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389 votes
35 answers
639k views

Why isn't Java used for modern web application development? [closed]

As a professional Java programmer, I've been trying to understand - why the hate toward Java for modern web applications? I've noticed a trend that out of modern day web startups, a relatively small ...
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
295 votes
16 answers
30k views

Grokking Java culture - why are things so heavy? What does it optimize for? [closed]

I used to code in Python a lot. Now, for work reasons, I code in Java. The projects I do are rather small, and possibly Python would work better, but there are valid non-engineering reasons to use ...
Mikhail Ramendik's user avatar
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
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
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
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
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 ...
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 ...
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
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
148 votes
2 answers
84k views

What is a "shaded" Java dependency?

JVM developer here. Lately I've seen banter on IRC chat rooms and even in my own office about so-called "shaded" Java libraries. The context of the use will be something like: "Such and so provides ...
smeeb's user avatar
  • 4,890
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 ...
140 votes
7 answers
52k views

Why doesn't Java 8 include immutable collections?

The Java team has done a ton of great work removing barriers to functional programming in Java 8. In particular, the changes to the java.util Collections do a great job of chaining transformations ...
GlenPeterson's user avatar
  • 14.9k
137 votes
6 answers
134k views

Why does the TRACE level exist, and when should I use it rather than DEBUG?

In Log4J, Slf4J and a couple other logging frameworks in Java, you have two "developper" level for logging: DEBUG TRACE I understand what DEBUG does, because the explanation is clear: The DEBUG ...
Laurent Bourgault-Roy'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
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
128 votes
11 answers
89k views

Why use Optional in Java 8+ instead of traditional null pointer checks?

We have recently moved to Java 8. Now, I see applications flooded with Optional objects. Before Java 8 (Style 1) Employee employee = employeeServive.getEmployee(); if(employee!=null){ System....
user3198603's user avatar
  • 1,896
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
118 votes
12 answers
20k views

Rationale to prefer local variables over instance variables?

The codebase I'm working on frequently uses instance variables to share data between various trivial methods. The original developer is adamant that this adheres to the best practices stated in the ...
Alexander's user avatar
  • 1,073
116 votes
6 answers
105k views

Is it better to use assert or IllegalArgumentException for required method parameters?

In Java, which is more highly recommended, and why? Both types will throw exceptions, so in that regard handling them is the same. assert is slightly shorter, but I'm not sure how much that matters. ...
Daenyth's user avatar
  • 8,147
115 votes
3 answers
111k views

What is the name of a function that takes no argument and returns nothing? [closed]

In Java 8's java.util.function package, we have: Function: Takes one argument, produces one result. Consumer: Takes one argument, produces nothing. Supplier: Takes no argument, produces one result. .....
superbob's user avatar
  • 1,322
111 votes
5 answers
95k views

Why were default and static methods added to interfaces in Java 8 when we already had abstract classes?

In Java 8, interfaces can contain implemented methods, static methods, and the so-called "default" methods (which the implementing classes do not need to override). In my (probably naive) view, there ...
Mister Smith's user avatar
  • 2,977
110 votes
13 answers
20k views

Should we avoid language features that C++ has but Java doesn't?

Suppose I am limited to use C++ by the environment in the project. Is it good to prevent the use of some language features that C++ has but Java doesn't have (e.g.: multiple inheritance, operator ...
ggrr's user avatar
  • 5,783
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
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
105 votes
17 answers
20k views

Is encapsulation still one of the elephants OOP stands on?

Encapsulation tells me to make all or almost all fields private and expose these by getters/setters. But now libraries such as Lombok appear which allow us to expose all private fields by one short ...
Gangnus's user avatar
  • 2,817
104 votes
18 answers
69k views

Is it poor programming practice to pass parameters as Objects? [duplicate]

So, we've got a guy who likes to write methods that take Objects as parameters, so they can be 'very flexible.' Then, internally, he either does direct casting, reflection or method overloading to ...
104 votes
10 answers
16k views

Has / can anyone challenge Uncle Bob on his love of removing "useless braces"?

I hate referencing paywalled content, but this video shows exactly what I'm talking about. Precisely 12 minutes in Robert Martin looks at this: And says "One of my favorite things to do is getting ...
candied_orange's user avatar
104 votes
5 answers
50k 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 ...
InformedA's user avatar
  • 3,021
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
100 votes
3 answers
40k views

What does "GPL with classpath exception" mean in practice?

Oracle seems to license all their Java-related open source code under the GPL with a classpath exception. From what I understand, this seems to allow to combine these libraries with your own code into ...
Thilo's user avatar
  • 4,786
97 votes
6 answers
142k views

Difference between a service class and a Helper class [closed]

I would like to know what differentiates a Service class from a utility class or a helper class? A class only with underlying methods calls the dao's is a service? Doesn't the usage of Helper ...
tintin's user avatar
  • 1,243
97 votes
9 answers
27k views

Why is it hard to make a Java program 'appear native'?

Most Java applications don't look the same as C/C++ applications. Swing might have been designed on purpose to have a distincitve look, but based on what I've read, SWT for example tried to 'look ...
user3150201's user avatar
  • 1,207
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 ...
92 votes
16 answers
21k views

Do the young minds need to learn the pointer concepts?

Why did the C master Dennis Ritchie introduce pointers in C? And why did the other programming languages like VB.NET or Java or C# eliminate them? I have found some points in Google, and I want to ...
91 votes
10 answers
54k 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 ...
IntelliData's user avatar
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
87 votes
10 answers
109k views

How many lines per class is too many in Java? [closed]

In your experience, what is a useful rule of thumb for how many lines of code are too many for one class in Java? To be clear, I know that number of lines is not even close to the real standard to ...
Michael McGowan's user avatar
86 votes
6 answers
20k views

Why are floats still part of the Java language when doubles are mostly recommended instead?

In every place I've looked, it says that double is superior to float in almost every way. float has been made obsolete by double in Java, so why is it still used? I program a lot with Libgdx, and ...
Eames's user avatar
  • 885
86 votes
13 answers
166k views

Why isn't Java more widely used for game development? [closed]

I'm not a game developer or anything, but I know that Java is not very widely used for game development. Java should be fast enough for most games, so where's the catch? I can think of some reasons: ...
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
86 votes
3 answers
157k views

Is this an appropriate use of Mockito's reset method?

I have a private method in my test class that constructs a commonly used Bar object. The Bar constructor calls someMethod() method in my mocked object: private @Mock Foo mockedObject; // My mocked ...
Duncan Jones's user avatar
  • 1,402
85 votes
4 answers
10k views

What's the difference between "to" and "as" method name prefixes? [closed]

What's the difference between "to" and "as" method name prefixes like toList(), asList(), etc... When to use which when designing a method?
Daniel Hári's user avatar
85 votes
13 answers
98k views

Is it good practice to catch a checked exception and throw a RuntimeException?

I read some code of a colleague and found that he often catches various exceptions and then always throws a 'RuntimeException' instead. I always thought this is very bad practice. Am I wrong?
RoflcoptrException's user avatar
84 votes
13 answers
38k views

Why would it ever be possible for Java to be faster than C++?

Sometimes Java outperforms C++ in benchmarks. Of course, sometimes C++ outperforms. See the following links: http://keithlea.com/javabench/ http://blog.dhananjaynene.com/2008/07/performance-...
Deets McGeets's user avatar
83 votes
12 answers
29k views

What is the utility and advantage of getters & setters especially when they are merely used to read and assign values to properties of an object? [closed]

I’m still really new to learning to program. Just learning the syntax for a few programming languages at the moment. The courses I viewed for C# and Java touched only very briefly on getters & ...
ProjectDiversion's user avatar
83 votes
8 answers
71k views

Is modifying an incoming parameter an antipattern? [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 ...
CsBalazsHungary's user avatar
82 votes
6 answers
163k views

Service layer vs DAO -- Why both?

I have been working with SpringMVC, Hibernate, and some databases in a java web application example. There are a few different ones that do this, but this Spring 3 and hibernate integration tutorial ...
Jeff's user avatar
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