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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Tic-Tac-Toe Java : Button Issues [migrated]

I've created a little TicTacToe game in Java and I figured to write more effcient code, I'd make a for loop to create the 9 buttons. The issue I'm having is figuring out how to test now which button ...
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1answer
101 views

ActiveRecord equivalent in Java [closed]

My question is fairly simple.. What is the closest ORM to ActiveRecord that I'd be able to find for Java? In other words, in terms of thinking patterns and knowledge, with limted development time, ...
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3answers
151 views

Good or bad idea to create a “fromJSON” static factory constructor for an object that is often created by parsing a JSON coming from API?

I have a "Product" POJO class in my app. A Product object can either be created in-app by the user or by parsing a json that comes from the API. Product has 20+ fields, but Im using only 2 here for ...
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1answer
103 views

Adding a graphical view to a system

I currently have an program in Java that simulates railway movements. Essentially, trains arrive on platforms, pick up and drop off passengers, and then proceed, respecting signalling where possible. ...
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5answers
465 views

Should I create a single object for a common method call or use a throw away approach?

I'm creating a little rpg fight program just for fun and to practice my java (I'm pretty new hehe). I have a class called Dice with a method called d20 that rolls a random number between 1 and 20. ...
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0answers
124 views

How to separate out below tightly coupled classes

I have two classes which are somewhat tightly coupled to one another. Lets call them A and B. A derives from C and B derives from D. B is the class whose instance is created by the system and then B ...
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4answers
229 views

Identifying user of a webapp

For a small webapp I want to be able to identify a user. The issue is, if the user cheats in some manner, I want to be able to forbid him the usage of my application. I already have done extensive ...
1
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1answer
67 views

Limiting complexity in JPA programs Java/Hibernate

I've been working on a new application for some months now. It's my first big JPA program, and is still in the early stages. However, the complexity of my JPA object tree is becoming a growing ...
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2answers
80 views

How to randomly get or find a sub-tree (include root node) from a given tree that contains n leaf-nodes

I have a non-binary tree. I want to randomly find a "sub-trees" that are connected from root to leaf which must have at least n leaf-nodes (leaf-nodes of sub-tree must be leaf-nodes of given tree). ...
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0answers
2 views

How to display the decrypted file in Java without File Output? [migrated]

I am trying to develop a system that will decrypt a file then allows the authorized user to view it without saving the decrypted file. This is to ensure that the other user won't be able to open the ...
0
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1answer
66 views

Controlling concurrency by Thread Pool in scenario of CPU-intensive and I/O intensive requests?

My goal is to understand how to handle jobs coming from the client side at very high frequency each job is either CPU-intensive or I/O intensive, but both types of jobs are continuously arriving at my ...
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0answers
101 views

How do I find which code is unused once my unit tests have been written? [migrated]

I'm developing unit tests to cover all of my code, but in IntelliJ IDEA the code no longer shows as "unused" because I have a unit tests which cover them. Is there a way to exclude unit tests from ...
3
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2answers
210 views

How should blank/empty value objects be instantiated/structured?

I was wondering... what is considered the best practice to instantiate blank value objects? (in Java) E.g. Assume we have some value object class Foo, that could be blank. Would creating methods ...
12
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2answers
515 views

Taming the 'utility functions' classes

In our Java codebase I keep seeing the following pattern: /** This is a stateless utility class that groups useful foo-related operations, often with side effects. */ public class FooUtil { ...
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1answer
143 views

Is this database design good? What JPA Entities should I create for this design?

I am trying my hands on JPA. For this I am thinking of using the example of a student admission process as shown in the diagram below. Is this design good ? Any suggestions for improvement are ...
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1answer
60 views

Bootstrap licence free template

I´m creating a new website. For that I´m using a free bootstrap template. On top of my index page I have: A Design by W3layouts Author: W3layout Author URL: http://w3layouts.com License: ...
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1answer
109 views

Where would be better to handle an exception?

Imagine I have the following DAO method: public Employee getEmployeeById(Integer id){ NamedParameterJdbcTemplate jdbcTemplate = new NamedParameterJdbcTemplate(getJdbcTemplate()); String sql = ...
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0answers
5 views

Extract variable references in Javac [migrated]

I am developing a java program extends TreeScanner from com.sun.source.util. I am looking for sth like visitMethodInvocation, but for variable. I was wondering if there is a way to extract variable ...
0
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1answer
137 views

What kind of reputation does Java 8 have among “enterprise” companies? [closed]

Are the new, functionally-inspired features of Java 8 well-regarded within the enterprise development community? Have they been adopted by large companies? Have coding standards been updated to ...
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2answers
188 views

Is using generics to indicate some class/method is aware of a type good idea?

I'm going to use Java for code/idea demonstration. Imagine it's needed to define two interfaces: Observer and Observable (observer pattern). It's a good idea to have two generic interfaces, so there ...
21
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8answers
2k views

Is there a conventional way to combine file path strings?

In an example: var assets = "images/" var sounds = assets+"sounds/" Is it more conventional to put the slash on the back of a file path? var assets = "/images" var sounds = assets+"/sounds" Is ...
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0answers
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Change IntelliJ code construct symbols [migrated]

Is there a way to change the icons for symbols suchs the C for classes and the M methods. They're a little hard to distinguish on my laptop. Ideally I'd like to change it throughout the IDE but fine ...
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4answers
155 views

Adding values to HashMap

I want to add values to a HashMap, which would be used by methods in the same class. I have two solutions: Adding all the values with static When the first method is called, add the values ...
2
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4answers
132 views

Range of values based on key values

I'm trying to implement a method of searching trough a large amount of 2D points for those that match a certain range. I'm thinking of creating HashMaps for <X, Point> and <Y, Point> but ...
2
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1answer
107 views

How to access secure web services from a desktop application?

I'm writing a Java desktop application that will be available to the public. It will contact backend APIs via HTTPS using Jersey client. I don't know anything about using certificates in desktop apps ...
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9answers
3k views

What is different between the internal design of Java and C++ that lets C++ have multiple inheritance? [duplicate]

It's drilled into the newbie Java programmers that Java (pre-Java 8) has no multiple class inheritance, and only multiple interface inheritance, because otherwise you run into diamond inheritance ...
2
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3answers
183 views

Declaring lambdas in Java8

What would be the best practice to declare lambdas in Java8 code? How it was designed to be used? For example, let's say that we have a method that accept a Function. I want to provide function ...
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1answer
210 views

String[] args vs (String . . . args)

When programming for android, whenever I use an AsyncTask the doInBackground method looks like this. protected String doInBackground(String... args) But when using the arguments anywhere in that ...
10
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1answer
343 views

Efficient way to represent hexagonal board logic for abalone-like games

I have to implement the AI for Abalone game and I'm wondering what is the best way to represent the board logic using Java without wasting too much resources in all checks and updates routines ...
6
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3answers
281 views

Design solution for communicating between multiple layers

We are developing a framework that has several layers and would be deployed in a multi-threaded environment. Each layer may have its own input/output data type. The top layer takes the input, performs ...
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1answer
63 views

excute Vs excuteOnExecutor [closed]

There are two ways to execute AsynTask, i.e., execute and executeOnExecutor. I already know that execute works serially and executeOnExecutor works in parallel. So my question is: Which one to use? ...
2
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3answers
91 views

Design a Queuing Solution with Clustering and Multiple Consumers

It is a Design Problem which I am listing out here. I have different set of business operations that are carried out for different business entities. Operations: Operation A Operation B Operation ...
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2answers
86 views

JUnit3 and JUnit4 in the same project (but different module)? [closed]

I have an Android project with a Gradle build. We've decided to commit to writing a vanilla Java implementation of our business logic (since we took care to keep that divorced form the Android ...
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2answers
113 views

Overriding methods by passing as argument the subclass object where the supertype is expected

I am just learning Java, and am not a practicing programmer. The book I am following says that when overriding a method, the argument types must be the same, but the return types can be ...
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1answer
49 views

Java Doc - Do fields also get documented?

This is a really simple question but oddly, I'm finding it difficult to get a definite answer.... What do you do with fields? Is this valid? /** * Keeps track of all usernames in the system. */ ...
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0answers
63 views

Best approach to save relationship mapping of country,state,city in orm

I am building a project in play framework java with jpa and I want set country,state,city dropdown fields in a form to be dynamic(from database).So only admin can increase or decrease the value of ...
0
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1answer
151 views

What'd be better? To add one more local variable, or to call a method twice in general case?

I have the method which returns java.util.Date inside the hibernate-entity class: package ua.com.winforce.loto_partner.commons.db.entity; @Entity @Table(schema = "pr", name = "publice") public class ...
2
votes
0answers
123 views

Object caching in this code too expensive?

I'm having some trouble with a game developed in Java which is kinda slow. I benchmarked it a little bit and found the problem: most of the time, the JVM is in the Object.<init>() since there ...
2
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2answers
237 views

Development on Android without using Java [closed]

As the title of this question suggests, I am looking forward to develop app(s) on Android platform without using Java at all. It doesn't mean I have some kind of vendetta against this beautiful ...
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0answers
36 views

Using a mock Spring bean

I m actually introducting to unit testing with Junit and I am wondering if I m doing the things right. In fact, I want to test a service in which I inject a repository (a Spring bean in my case with ...
1
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1answer
60 views

JSP without .jsp-files?

I have a little project (a CMS) that was developed using .jsp-files in 2006. I moved in 2011 to JSF and had only one .jsp-file for the frontend. In 2014 I integrated the backend into the frontend ...
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votes
1answer
152 views

What's the returning a value in Java?

public void warning(){ System.out.println("Watch out!"); } public void warning(){ System.out.println("Watch out!"); return; } We must use "return" statement with void methods. Bot ...
0
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1answer
57 views

Reflection performance in this iteration of a (probably) large excel file

I'm wondering the performance of reflection in this situation. I'm iterating a (probably) large excel file (let's say 3000 max) which it's going to be done from time to time, and the implementation ...
0
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2answers
47 views

Which 'InputStream' subtype is used by 'Socket' type object here?

In the below server socket program, byte stream object is used to read data from client, as mentioned - InputStream in = socket.getInputStream(); public class SingleThreadTCPServer{ ...
1
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1answer
56 views

Query on java I/O BufferedOutputStream write() method

Below is the code that is written using byte stream non-buffer class FileInputStream and FileOutputStream with the usage of explicit user buffers. public class FileCopyUserBuffer{ public static ...
0
votes
1answer
167 views

Shortest path to visit all nodes [duplicate]

I am given a set of tourist attractions(nodes identified by x, y) and i need to find the shortest path to visit them. The way i thought of it, is i will ignore if there are streets available and ...
3
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1answer
62 views

Template pattern with varying input type in overridden method

I am trying to use template pattern to define a generic algorithm in java. But the method that needs to be overridden, takes an object as input. This object will vary depending on the concrete ...
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1answer
145 views

Whats the difference between byte and Byte? [duplicate]

Alright so of course, I know the differences. byte is a primitive and Byte is an object. Byte offers more functions but there is one thing I dont understand. Why would anyone create a variable using ...
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1answer
164 views

Why is close() implemented in InputStream/OutputStream?

It make sense to see close() as non-core functionality of stream objects. This is the reason this method is placed in interface Closeable. One evidence is that class ByteArrayInputStream does not ...
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2answers
64 views

Query on hiding implementation details in java

With the below piece of thread related code, I see that author of Thread class is hiding the details about the working of start() method. What a user of Thread class need to know is, class Thread ...