0
votes
0answers
105 views

How can I re-use object from another project?

I have a first project has a feature to viewing, inserting and updating an employee record, with this possibly I will create a java class for the UI and another for the database connection with ...
2
votes
3answers
222 views

Inheritance: Is code from superclass virtually *copied* to subclass, or is it *referred-to by subclass*?

Class Sub is a subclass of class Sup. What does that mean practically? Or in other words, what is the practical meaning of "inheritance"? Option 1: The code from Sup is virtually copied to Sub. (as ...
4
votes
3answers
458 views

What is the process of determining which method in a class hierarchy should execute known as?

I thought I understood inheritance and polymorphism, but I was given this question, and I can't, for the life of me, figure out what the proper answer is or what they're trying to get at: The ...
-1
votes
0answers
57 views

Java: Singleton Event Driven Design [closed]

I have a singleton class ( I make this as immutable ). This class is present in the base module. It has a static method getInstance() which will initialize a new object based on the data stored in a ...
0
votes
1answer
149 views

My UML class diagram is too complicated, what should I do?

Classes have 10-20 links with one another and you can't see anything in that mess of a diagram Unfortunately we finished coding already and if we change the class diagram we have to redo the whole ...
1
vote
1answer
144 views

Java code quality in methods calling methods

I am currently working with an "interesting" code-base and see the following type of thing alot in the code. public Object doSomething() { Object obj = new Object(); // Do some stuff to the ...
24
votes
5answers
3k views

Why is it bad to write something in language X as if you're writing a program in language Y in terms of using a shared coding paradigm [closed]

A while ago, I asked a question on SO about something written in C++, but instead of getting an answer to the problem at hand, the comments went all crazy on my coding style, even when I indicated ...
0
votes
0answers
3 views

Number Patterns using loops in Java [migrated]

I have been trying different variations of for loops and have no clue how to make these patterns: Pattern 1 54321 5432 543 54 5 Pattern 2 1 12 123 1234 12345 Pattern 3 12345 2345 ...
4
votes
1answer
203 views

Which relationship is more natural?

Have a quick question on how to best structure something for my Java project: I'm a user. I can work at one or more places. At those workplaces, I have one or more roles. For each of these roles, I ...
1
vote
1answer
300 views

Objects as parameters: Is there a simple way that explain this? [closed]

I tried to understand how objects can be passed as parameters but it was difficult for me. How can we pass an object as a parameter to a method of another object? I need to understand the idea behind ...
10
votes
9answers
2k views

Is there any difference learning OOP on different programming languages? [closed]

I want to learn OOP. I know Python and I know very little things about OOP. But when I search for "learn OOP" in forums I saw a guy saying that "Python is so new that's why you can't learn OOP on ...
18
votes
2answers
2k views

How to improve upon Bloch's Builder Pattern, to make it more appropriate for use in classes that may be extended and sub-extended many times over?

I have been greatly influenced by Joshua Bloch's Effective Java book (2nd edition), probably more so than with any programming book I've read. In particular, his Builder Pattern (item 2) has had the ...
1
vote
1answer
110 views

Use of # in answers/documentation when referring to methods of a class

When looking through Java documentation or answers for Stack Overflow / programming forum questions, I often see people referring to methods like String#format, Object#clone etc, rather than ...
0
votes
2answers
124 views

Best way to display domain object summary information efficiently and in an OO way from a large inheritance tree?

I've provided only simplified code as it's more of an abstract design question. So I have many, many nested business/domain event objects, e.g. public class Event { //bunch of properties and ...
8
votes
4answers
584 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: ...
2
votes
3answers
240 views

Framework in which views are defined in the database - design flaw or reasonable?

I'm working with a framework where the fields displayed on each web page are defined in the application database. Administrators can add new fields to pages or hide/completely delete old fields. The ...
0
votes
1answer
127 views

What's a similar functionality in JavaScript that insures the object has X data before any actions are taken?

If java/C#/etc one might do something like create a constructor with a parameter, the parameter being the thing the rest of the object may act upon. How is this done in JavaScript? I'm trying to ...
1
vote
2answers
188 views

An alternative to having fields that might not be used in a class

I'm writing a card/ board game in Java. Since the game has lots of cards that interact in different ways, my Player class has become sort of bloated with all these different fields used for keeping ...
2
votes
1answer
214 views

Any programming languages that support Generics exclusively and have no OOP support? [closed]

I am writing a paper on the tension between OOP and Generic programming created by Stepanov. He widely criticizes OOP and says it is "technically flawed" when compared to Generic Programming. Now I ...
1
vote
1answer
351 views

Readability vs benefits of polymorphism

We are dealing with a lot of CRUD operations in our application. Each database table has one or more corresponding SQLContainer instances to perform various types of operations. All of these ...
0
votes
3answers
131 views

Design for a template class

I have an abstract class abstract class MathFunc that is used to implement the mathematical functions Rastrigin, Griewangk and Rosenbrock in their specific classes final class Rastrigin extends ...
5
votes
2answers
363 views

Is this a correct implementation of an Immutable class in Java?

public final class ImmutableClass { private StringBuffer name; public ImmutableClass(StringBuffer name) { this.name=name; } public StringBuffer getName() { return ...
0
votes
1answer
192 views

Emulation of MMU accessing the contents of the registers

I'm having a play around with emulating a simple old CPU. I've set the structure up, so far anyway, as follows: The device is the main and creates an instance of the CPU. The CPU then creates ...
32
votes
3answers
1k views

Does Java development typically involve more subclassing than C#/.NET?

I've recently started looking at Android development. This has brought me back into the world of Java software development. The last time I worked with Java, I'll admit, I didn't understand OOP nearly ...
0
votes
4answers
122 views

Understanding parameters

I have read this statement: "A parameter is used as a sort of temporary messenger, carrying data originating from outside the constructor or method and making it available inside it." So, does that ...
3
votes
1answer
494 views

What are the disadvantages of self-encapsulation?

Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use ...
4
votes
5answers
495 views

How to model an address type in DDD?

I have an User entity that has a Set of Address where Address is a value object: class User{ ... private Set<Address> addresses; ... public setAddresses(Set<Address> ...
4
votes
4answers
638 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 ...
2
votes
7answers
477 views

Is there a pattern to restrict which classes can update another class?

Say I have a class ImportantInfo with a public writable property Data. Many classes will read this property but only a few will ever set it. Basically, if you want to update Data you should really ...
15
votes
4answers
651 views

Empty interface to combine multiple interfaces

Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these ...
0
votes
2answers
825 views

Object oriented immutability: final classes or final methods

One of the things you see in numerous places in the standard java library is final classes. It is claimed that this is for immutability which I understand...to an extent. Suppose you have a class: ...
1
vote
1answer
163 views

When should one use composition instead of re-writing the functionality?

Say, I have a class A which has methods m1,m2,m3,m4,m5.... m100. I am making another simpler class B and I require only m2,m3 and m5 in B. Should I be ideally using compositions and put a reference ...
2
votes
2answers
425 views

OOP Objects, nested objects, and DAO's

Here's something I keep struggling to figure out the best solution to. I've had this problem while working with PHP and Java so it's a fundamental understanding of OOP issue. Examples are in PHP. ...
1
vote
4answers
456 views

How to get Object Oriented Programming Concepts? [closed]

What is the best way or best resources or tutorials to learn Object Oriented Programming? For instance, when I begin a program with Java and all my code goes into just one class and I can't estimate ...
1
vote
1answer
112 views

how to model a connection to a resource, with rudimentary event processing

For my simple MUD client I'm using Apache Telnet (no, not ssh). A mud client is a strange beast: Generally, a MUD client is a very basic telnet client that lacks VT100 terminal emulation and the ...
4
votes
2answers
695 views

How does MVC work with the principle “Tell, Don't ask”?

Procedural code gets information then makes decisions. Object-oriented code tells objects to do things. — Alec Sharp So, when a view wants to display some information that is suppose to be ...
0
votes
3answers
251 views

Liskov substitution principle when implementing two unrelated interfaces

Suppose I have two unrelated interfaces with the same method: interface Table { /** * @param width (0 < width <= 100) */ void setWidth(int width); } interface Square { ...
0
votes
2answers
2k views

How to update an existing excel file using java program? [closed]

I've made a file browser in java that opens and read already been made excel files. (using Apache poi 3.9 library) program read those files perfectly but i want to update some of those files. how can ...
22
votes
4answers
1k views

Why Java doesn't make use of encapsulation with some classes?

My question is related with System.in and System.out classes (there might be others like those in the Standard library). Why is that? Isn't that a bad practice in OOP? Shouldn't it be used like: ...
0
votes
1answer
242 views

Can we call final field as object's constant?

We call static final fields as constant, rather I should say Class constant. So can we call just final fields as Object's constant? Is it right to say this? Edited :: Consider the following code : ...
2
votes
3answers
376 views

Parallel Class/Interface Hierarchy with the Facade Design Pattern?

About a third of my code is wrapped inside a Facade class. Note that this isn't a "God" class, but actually represents a single thing (called a Line). Naturally, it delegates responsibilities to the ...
5
votes
1answer
264 views

Should I use JavaFx properties?

I'm usually very careful to keep my Model, View, and Controller code separate. The thing is JavaFx properties are so convenient to bind them all together. The issue is that it makes my entire code ...
1
vote
4answers
462 views

Explanation of the definition of interface inheritance as described in GoF book

I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between ...
2
votes
4answers
146 views

Subclassing to change default settings?

I have a class called Timeline. I want to allow several defaults in my code, such as a Timeline with a Start event (The details are not needed. All that matters is that I have a class, and I want to ...
1
vote
2answers
151 views

Determining the aggregates in this domain

I'm working on an ordering system where we receive tab delimited files that look like this (I removed most of the columns for clarity): OrderId OrderLineId BuyerName BuyerAdress ...
3
votes
4answers
358 views

Law of Demeter causing subclassing indecision and conflict with Single Responsibility

This is my situation: I have a class called CueList, which is basically a wrapper around ArrayList. I have another class called TimeTicker that alerts all the Tickable (interface) in its list that a ...
12
votes
5answers
902 views

What makes JVM so much versatile to support so many JVM languages?

JVM supports so many languages other than Java like Groovy,Clojure,Scala etc which are functional languages unlike Java(I am referring to Java before Version 8 where Lambda's are not supported) that ...
3
votes
1answer
289 views

Question about Java nested classes design decision

I was shocked today to discover that this code compiles cleanly in Java: public class A { public static class B { private static void x() {} } private static class C { private /* So, ...
1
vote
1answer
154 views

How do I create a mutually-incompatible type library in Java?

Folks, this seems like it should be straightforward, but I'm drawing a blank here. As a simplified example, consider an abstract class called Number with an abstract method add(). I want to create ...
3
votes
3answers
130 views

Representational Equality versus Value Equality

I am coding a system where I have objects which represent a set of resources. These resources are identifiable (they have an ID). There can only be one resource with the same ID, and so multiple ...