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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Method passing integer value not responding for java GUI

I am doing two separate program, one is call MyNoteCenter and the other one is call SocketServer In MyNoteCenter, there consist of this portion of program if(e.getSource()== btn2) { ...
6
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3answers
127 views
+50

Separate interface for mutation methods

I've been working on refactoring some code, and I think I may have taken the first step down the rabbit hole. I'm writing the example in Java, but I suppose it could be agnostic. I have an interface ...
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1answer
25 views

How to send a string value from client side to server side?

I am developing a client server program which consist of combo box for user selection in client program. After the client make his choice, the download button will send the request to my server ...
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2answers
117 views

Why Java does not have a framework like Rails? [on hold]

I am a Ruby on Rails developer and I like its simplicity and rapidness. On the other hand we need to use Java for some projects that we develop for our clients. My question is why (pure) Java does ...
-3
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2answers
158 views

How 'Encapsulation' is different from 'Data abstraction'? [on hold]

class DblyLinkList below, follows these 2 definitions mentioned in this answer. Term representation is used in in place of implementation in the code. Abstraction has to do with separating ...
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1answer
43 views

Why are Strings in StringPool considered insecure?

Passwords are recommended to be stored in char[] instead of String, as Strings are stored in StringPool. Read more here As per this question Strings in StringPool are not available directly. To ...
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0answers
104 views

how can i store floating point numbers in integer type variables e.g: 24.49

how can I store a number before decimal into integer or after decimal into integer example: float=24.49 it should print like this: int a=24; int b=49; what can be the logic behind this??
-2
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0answers
17 views

RESTful web service in Jersey

Im creating a RESTful web service through Jersey. I followed the guide http://javapapers.com/java/restful-web-services-with-java-jax-rs-using-jersey I created the web service as mentioned in the ...
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1answer
43 views

Is Glassfish Or TomEE better than plain Java Web Container? [on hold]

I am trying to migrate my plain Apache Tomcat 7.0 Server to Glassfish or TomEE, but I'm hesitating to decide because I'm afraid it can cause a performance impact. In plain Apache Tomcat I can ...
1
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1answer
29 views

Database + Java Design for a scenario

Overview A central web application to supports other web applications(A) for user and its role/permission management. Applications (A) call the central application via API to get the user ...
32
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10answers
23k 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 ...
-4
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0answers
34 views

i am trying to print age, height and name using the concept of multiple constructor is java but something is wrong. can anyone help me please? [on hold]

// this is my timePractice class package timepractice; public class TimePractice { public static void main(String[] args) { timeRegular obj = new timeRegular(); obj.setAge(20); ...
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45 views

Writing html via Java

I have some information stored on my computer in text files. I use Java to manipulate, format, and process this data. I would like to write a program in Java that will result in the data appearing on ...
1
vote
1answer
93 views

Is it possible to build up a “stack trace” from the code (using some tool) in Java

To analyse workflows in a bigger environment I usually spend a fair amount of time walking through code by using "go to implementation" or "find usages" lookups. But after 4 or 5 jumps its sometimes ...
-1
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0answers
14 views

register action working very fine but there is a problem in login that it couldn't find its corresponding result [on hold]

LoginAction--- package actions; import java.util.Date; import java.util.Map; import com.opensymphony.xwork2.Action; import com.opensymphony.xwork2.ActionContext; import dao.UserDao; public ...
0
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1answer
75 views

Immutable class with behavior

I've just finished Effective Java and I loved it. I'm trying to refactor one of my programs to take advantage of what I've learned, and I have a lot of questions regarding immutability. My program is ...
1
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1answer
37 views

Is it appropriate to pass in a derivative to calculate the error of a Neural Net?

I'm reading a guide for back-propagation of a neural net, and it gives the error function as: Next work out the error for neuron B. The error is What you want – What you actually get, in other ...
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0answers
33 views

Better Approach for retrieving multiple RESTful calls

I have an Android application that associates bluetooth beacons with data that is retrieved from a server via RESTful calls. Once the app is launched, we have a page with a table that is being filled ...
1
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0answers
50 views

Separate GUI for clients

I am writing a game in which I have a Java server/client system set up. Everything is working great, but I reached a slight problem. I have set up a basic health system, and a GUI to go with it (for ...
-1
votes
1answer
100 views

Carriage return not working properly in eclipse [on hold]

Carriage return is not working when i execute the program it produces the n number of characters after "\r" in a newline class NewClass{ public static void main(String args[]){ String str = "Hey ...
2
votes
2answers
81 views

When should I instantiate a variable rather than grabbing it through a method?

This may be tedious, but I would love to know which is a more efficient way of programming. The result may only be slightly better or slightly worse, but I am still interested in which is 'better'. ...
1
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0answers
66 views

The same objects are staying in memory across multiple executions

I was testing a neural net I created, and noticed something odd. The net uses a hashed adjacency list (roughly) to maintain its links. The vertices of the list are the nodes of the net. I chose to ...
6
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9answers
1k views

How to teach computer science? [closed]

I am just starting to teach computer science. It's just the basic level. I'm finding that I sometimes don't know how to approach topics in a way that lets students easily understand. I've found that ...
23
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17answers
6k views

What are some good assignments for an introductory course, to reach today's students? [closed]

I periodically teach an introduction to programming course using Java. I want to give my students some exciting assignments that they can relate to or find interesting. At the very least, I want ...
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0answers
38 views

Difference between == and .equals (java) [on hold]

I store my game map as Tile tiles[][] array For singleplayer game in render fuction I can use if (map.data[x][y].group =="crappyblocks") {do ......} Group is a string. I started making basic ...
3
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2answers
199 views

Is it worth it to use a message-queue framework in this case?

We have these things called "executions" that are run at certain times. They have a delay property that basically says "execute me after delay microseconds`. Currently we are using Cassandra as a ...
4
votes
1answer
108 views

Why does Java define BigInteger / BigDecimal values of 10?

Question perhaps slightly left of field - but I'm curious as to the logic behind why Java's BigInteger/BigDecimal classes feel the need to define a constant of TEN? Example taken from ...
13
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10answers
1k views

Does low latency code sometimes have to be “ugly”?

(This is mainly aimed at those who have specific knowledge of low latency systems, to avoid people just answering with unsubstantiated opinions). Do you feel there is a trade-off between writing ...
0
votes
4answers
131 views

Handling DomainExceptions using REST endpoint

Suppose I'm doing some DDD. Now, I have a microservice reflecting a bounded context/a part of a bounded context. Now, suppose there is a REST endpoint: '/somedomainmodel/someaction' My API user is ...
6
votes
1answer
74 views

Optional features: default method or separated interface

Dedicated interfaces seems to be a good way to expose the optional features in a domain-specific type hierarchy. However, they impede the use of decorator and composite patterns, which is also common ...
1
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2answers
108 views

Could changing the return type from void to string introduce breaking changes?

This SDK have an interface like this: public interface Contract { void update(..); void action(..); void delete(..); } Now, we need to change it to something like this: public ...
-4
votes
1answer
83 views

Questions about a java developer job > semiconductor industry [on hold]

I am an experienced java ee developer and I got this job offer: A java developer for a company that produces software solutions for the semiconductor industry. I've got two questions: 1- ".. ...
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0answers
49 views

I need a program of factorial and then this [on hold]

Make a program that outputs a factorial of any number and then compute its running time and prove that that running time is an element of theta n^2
1
vote
1answer
5k views

Java desktop application using MVC + Hibernate

I'm developing a Java desktop application. I'm planning to use MVC architecture described at Oracle site: Java SE Application Design With MVC. I need to store data in database so I decide to use ...
0
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2answers
137 views

Design Patterns: What design pattern should I use for the following? [duplicate]

I am trying to write an utility which traverses through a list of files and searches for a string in each file. On finding the string in a file, I will add it to a list and display the list. Which ...
27
votes
6answers
4k views

Is throwing new RuntimeExceptions in unreachable code a bad style?

I was assigned to maintain an application written some time ago by more skilled developers. I came across this piece of code: public Configuration retrieveUserMailConfiguration(Long id) throws ...
0
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3answers
92 views

Implementing a Generic List in Java

In an effort to understand Generics in Java (and how to use them), I am trying to implement a list structure using them but have hit a wall. Scenario: Suppose there is some classes (we'll call them ...
-3
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0answers
27 views

What is the dereferenced in switch block? [on hold]

I executed the following code and I got the following errors. RunUnitConvert.java import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import ...
0
votes
0answers
31 views

How should I go about making a statistics analyser? [on hold]

I'm making a program which should analyse the stats of all soccer premier league players in fantasy football (form, price, fixtures, injuries etc) and using those stats, predict point potential/value ...
15
votes
6answers
1k views

Why does the TRACE level exists, 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 do, because the explanation is clear. The ...
2
votes
1answer
125 views

Good Coding practice with respect to interface versus class versus super class

I am currently reading the following tutorial and have gotten up through here http://docs.oracle.com/javase/tutorial/java/concepts/interface.html Maybe I should not be thinking about this question ...
-5
votes
0answers
46 views

Auto Moving Objects using Java [on hold]

Hi guys i am new to this field, but i am willing to learn java. So i have chosen games to learn java i am developing a game called Shooter, which requires images to move in its own...... So someone ...
2
votes
2answers
323 views

A 'task' system which has an ending, to get ready for next task

I want to make a system, so that there are certain tasks. For example, let's talk about a game. I want to make it so there are 100+ tasks doing different things, but when the player's magic level is ...
1
vote
3answers
180 views

How to use Guice for an effective API Design?

I am creating a base API in JavaSE, which includes modules like MVP architecture, Service & Repository Layer, Event Model to fire events between presenter etc. I am trying to implement all best ...
-4
votes
0answers
37 views

Windows custom lockscreen program [on hold]

I'd like to create a windows application that locks my screen, I want the program to have the same functionality as this program but I want to add functionality to it so I can play custom sounds and ...
0
votes
0answers
78 views

Is it possible to miss a connection?

I'm writing a simple asynchronous tcp server & client program and I am curious if it's possible that the method "waitForConnections" misses a connection because it's still busy with accepting the ...
3
votes
4answers
131 views

Design strategy for wrapping exceptions

I'm implementing a type of Repository for a framework/library that has (roughly) the following: public interface FooRepository { boolean contains(String id); Foo fetch(String id); void ...
2
votes
1answer
140 views

Finding the closest n points to any arbitrary point in two dimensions (r-tree, quadtree, spatial index)

I have a distribution of two dimensional point objects. How is it possible to find the nearest N number of points to any given point without iterating over the entire collection of points (and only ...
2
votes
1answer
366 views

DataMapper for a MMO game plugin to send packets

I am working on an plugin for some game-server. The information about the plugin is not really necessary. Few points you might find helpful to answer to this question: The server The server is ...
1
vote
0answers
87 views

Approach for polyglot logging

I'm building a desktop app with a Java front-end and very performance critical Fortran libraries. We've recently started pushing more of our code out of Java and into Fortran (see below) Soon we will ...