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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.

393
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35answers
571k 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 ...
288
votes
16answers
26k 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 ...
235
votes
14answers
88k 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 ...
230
votes
7answers
272k 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 ...
218
votes
6answers
100k 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: ...
200
votes
40answers
18k 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 ...
200
votes
6answers
47k 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 ...
170
votes
10answers
170k 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?
170
votes
16answers
120k 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 ...
168
votes
10answers
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 ...
137
votes
15answers
27k 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 ...
124
votes
6answers
47k 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 ...
122
votes
5answers
182k 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?
117
votes
11answers
51k 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 ...
110
votes
13answers
19k 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 ...
107
votes
12answers
14k 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 ...
101
votes
5answers
44k 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 ...
98
votes
10answers
37k 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....
98
votes
6answers
149k 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; //...
98
votes
9answers
24k 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 ...
97
votes
18answers
49k 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 ...
97
votes
17answers
16k 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 ...
97
votes
5answers
68k 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 ...
96
votes
4answers
63k 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 ...
96
votes
5answers
80k 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 ...
94
votes
10answers
11k 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 ...
94
votes
13answers
15k 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. ...
89
votes
16answers
18k 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 ...
89
votes
6answers
56k 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 necessarily? Most of these interfaces are only used by a single class and we are not creating any sort of public ...
86
votes
5answers
35k 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 ...
83
votes
6answers
16k 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 ...
83
votes
10answers
36k 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 ...
82
votes
17answers
14k 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 ...
81
votes
6answers
68k 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. ...
80
votes
11answers
11k 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 ...
78
votes
15answers
31k 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-...
78
votes
8answers
100k views

Why use try … finally without a catch clause?

The classical way to program is with try ... catch. When is it appropriate to use try without catch? In Python the following appears legal and can make sense: try: #do work finally: #do ...
78
votes
11answers
32k 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 ...
77
votes
11answers
20k views

Why aren't Java objects deleted immediately after they are no longer referenced?

In Java, as soon as an object no longer has any references, it becomes eligible for deletion, but the JVM decides when the object is actually deleted. To use Objective-C terminology, all Java ...
76
votes
13answers
133k 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: ...
75
votes
4answers
6k 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?
72
votes
10answers
6k views

Never use Strings in Java? [closed]

I stumbled upon a blog entry discouraging the use of Strings in Java for making your code lack semantics, suggesting that you should use thin wrapper classes instead. This is the before and after ...
72
votes
7answers
141k views

Why declare final variables inside methods? [duplicate]

Studying some classes of Android, I realized that most of the variables of methods are declared as final. Example code taken from the class android.widget.ListView: /** * @return Whether the list ...
71
votes
10answers
74k 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 ...
71
votes
7answers
64k 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 ...
69
votes
13answers
65k 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?
69
votes
4answers
7k views

Why were Java collections implemented with “optional methods” in the interface?

During my first implementation extending the Java collection framework, I was quite surprised to see that the collection interface contains methods declared as optional. The implementer is expected ...
67
votes
16answers
8k views

How much freedom should a programmer have in choosing a language and framework?

I started working at a company that is primarily C# oriented. We have a few people who like Java and JRuby, but a majority of programmers here like C#. I was hired because I have a lot of experience ...
67
votes
10answers
16k views

Why do languages require parenthesis around expressions when used with “if” and “while”?

Languages like C, Java, and C++ all require parenthesis around an entire expression when used in an if, while, or switch. if (true) { // Do something } as opposed to if true { // Do ...
67
votes
7answers
141k views

How is IntelliJ better than Eclipse? [closed]

I know there have been questions like What is your favorite editor/IDE?, but none of them have answered this question: Why spend the money on IntelliJ when Eclipse is free? I'm personally a big ...