Questions tagged [java]
Java (not to be confused with JavaScript) is a class-based, object-oriented, strongly typed, reflective language and run-time environment (JRE). Java programs are compiled to bytecode and run in a virtual machine (JVM) enabling a "write once, run anywhere" (WORA) methodology.
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Creating a numeric phone keypad
I'm writing a Telephone class and it has a method called getDigits which takes in a String parameter and returns the number that would appear on your phone if you ...
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1
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Brainfuck Interpreter: Slower than a Snail?
Inspired by FizzBuzz by Brainfuck, I decided to write an interpreter for Brainfuck. It:
Removes all non-command characters
Optimizes commands (removing +- and <...
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Lock for preventing concurrent access in client data
I am trying to implement lock by which I don't want to have reads from happening whenever I am doing a write.
Here is my ClientData class in which I am using ...
- 2,167
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An iterator returning all possible permutations of a list in Java
I have this class that iterates over all permutations of an input list:
PermutationIterable.java:
...
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Model simulation using Java annotations
A couple of days ago I posted my code that models systems made up of moving parts. I got several great tips and ideas and here is my latest version. My actions are now methods annotated with @Action (...
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Onion Run Festival (or the unexpected anagram for Union of Intervals)
Original question: Union of intervals
In the original code, the Interval model class implements Comparable so that an input of <...
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Fast alternative for String.split by whitespace
After profiling of one project I've found a bottleneck in the code, specifically the line:
String columns[] = line.split("\\s+");
I've tried to find a workaround,...
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Guess number game
I'm making a simple guess a number game. In game, user should input minimum and maximum value and program should generate random number between this numbers, later user should try and guess the number....
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Java Tic-Tac-Toe game (implemented through MVC)
After seeing Tic Tac Toe in MVC, I attempted to create something similar. My program uses the Swing library and it's relatively simple. When I run the game, it's just a 3x3 grid with no extra features....
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Efficient top k words using MultiMap (Google Guava ext lib JAR)
Basic algorithm:
Open document/huge text file
Use Map and List to separate the words. \$O(K)\$ time complexity (TC) considering ...
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Determining winner and winning hand in poker (holdem)
I wrote couple classes that calculate winner, winning hand and winning hands rank (straight, flush, fullhouse etc.). I searched for something similar, but only found posts where five cards are used, ...
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Improved Van Emde Boas tree based map in Java
After working on Van Emde Boas tree -based map in Java, I came up with this code. I managed to fix the bugs and improve the performance by using internally primitive integers instead of wrapped ...
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Producer/Consumer implementation
I am using Netty embedded within Grails to process and display incoming SNMP messages. Since Netty 4 doesn't come with a built-in ChannelExecutionHandler I had to ...
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DP solution to min triangle path
I am studying for interviews for various companies. I wrote a solution to this problem, but if an experience programmer looks at it I am sure there are certain areas the code can be made in to a more ...
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Missing level of technical depth (Recursive to Iterative)
I recently have given a coding test in a reputable IT company. There were three coding questions.
They refused me by saying that
as we felt they didn't demonstrate the level of technical depth we'...
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Beginners Java calculator
I am a beginner in Java programming, and I created a calculator as my first Java project. Therefore, can you review my code and provide feedbacks/ tips?
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IntModulus reloaded
As my question Modular arithmetic was hard to review and terribly long, I've added a few comments to the easier part, namely IntModulus.
The code uses Guava and ...
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Implementation of a graph in Java
A long time ago I posted my implementation of directed graph is Java. Recently I took a look at @coderodde's implementation and decided to write an implementation of undirected graph and directed ...
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Integer Partition using an iterator
I tried implementing Integer Partition (enumerating all possible sets of whole numbers whose sum is a given integer).
Looking at @rolfl's answer, I reasoned that with a stack data structure, we ...
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Kruskal's algorithm in Java
I have this Java implementation of Kruskal's algorithm. It solves a tiny problem instance correctly, yet I am not quite sure, whether my implementation is correct.
The code as follows:
MSTFinder....
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Missing level of technical depth (Flatten Tree)
I recently have given a coding test in a reputable IT company. There were three coding questions.
They refused me by saying that
as we felt they didn't demonstrate the level of technical depth we'...
- 409
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Long switch statement to lookup fifty-something commands
I have a very long switch statement which is expected to have nearly 50-55 cases.
...
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Optimizing unique partitions of integers
I am working on a project involving the unique partitioning of integers. I.e. I am looking to have all of the partitions of n = x1 + x2 + x3 + ... + xk, where xi = xj implies i = j.
For example, if I ...
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Multi-threaded domain status checking in Java
I'm tinkering with the idea of crafting a search engine in my spare time. More of a learning experience than anything at this point, but still a project. A key aspect of this system is checking ...
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A tiny library for textual serialization of lists in Java - follow-up 2
See the previous iteration. See the next iteration.
I emphasized the fact that serialization routine may not return a string with new line character by using more or less explicit identifier. Moved ...
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Karp-Rabin String Matching, Part 2
Part 1 is here. I wrote a Java implementation of the Karp-Rabin semi-numerical string matching algorithm. I incorporated the suggestions of @fge and @maaartinus from the other question into my new ...
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Project Euler #1 in Java
Project Euler #1:
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below ...
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A tiny library for textual serialization of lists in Java - follow-up
See the previous and initial iteration.
See the next iteration.
I have mainly refactored the code and made it a little bit robust (if serialization of a single object produces a string with new line ...
- 28.1k
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2
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Tracking Containers in a Train Station
This is a time line for control over the events of some containers in a train station.
It gets all the data to build the time line by getting a JSON from a database via REST service. The app resets ...
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Prime number util class
A prime number util, which provides 3 APIs - find the nth prime, find the next prime, and find all primes up to n.
I must admit this code has been influenced a lot by discussions here. I'm looking ...
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Triangulate the divisors and divide the triangulars
Project Euler 12 - Highly divisible triangular number
The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be \$1 + 2 + 3 + 4 + 5 + 6 + 7 = ...
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Find the missing number in a array
I'm working on a personal project to practice my programming skills and I came to this problem. I tried to create a program that will find the missing number in a array.
I'm looking forward to ...
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Android SQLite Database management
I'd like some opinions about my approach at using SQLite databases in android. Everything seems to work very well, but there may be something wrong that I hadn't noticed.
I don't like working with ...
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School grading string calculator
For my training, i've been given an assignment to build a simple, extendable 'grade' String calculator by a given grade.
For now, I had to work by this table:
When the ...
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Copy File, remove spaces in specific lines
This question now has a follow-up question 1 and follow-up question 2
As an exercise in writing decent code and because I learn best by example, I wrote this program and would ask for a review so ...
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Calculate Geometric and Arithmetic Mean
I am trying to make general class to calculate Geometric mean using exponential of the arithmetic mean of logarithms , and Arithmetic Mean.
I am looking for some general feedback on how I can improve ...
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Guess how many are in the jar game in Java - Take 2
Original question can be found here
I took the advice I got to heart, and re-wrote it. Once again I'd appreciate any advice as to how I can improve this using best practices.
Jar.java
...
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Project Euler #54 solution - follow-up
This is my second solution to Project Euler #54. You can find the original post here.
Brief problem summary:
The file, poker.txt, contains one-thousand random hands dealt to two players. Each line ...
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An Update on my TileMap Class
I'm making a old-school Final Fantasy type game and I made a tile map class a while back and posted it on here (Is this a good way to implement a tile map from a text file?) But, when I got to ...
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Find sum of number of times that each character of source occurs in the target
I wrote the following code in response to this question "find sum of number of times that each character of source occurs in the target", is there any better solution for it?
Analysis
...
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Video playlist interface in Swing
I wrote this piece of code for a GUI i am making, which is a playlist interface. I was wondering if I could write all of this code out differently, but to the point where it functions exactly the same,...
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Print columns of text without hard coding the width (attempt 5)
If you'd like to print this:
...
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Sudoku-Solver with GUI in Java
I've wrote a Sudoku-Solver in Java, which also contains a GUI, so you can just enter the Sudoku, press "OK" and it will solve the Sudoku using backtracking.
Here's the code:
...
user214772
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1
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Webscraping tennis data 1.1
I incorporated the substantial changes suggested in my previous question that involved building a web-scraper for gathering tennis data.
The improved code is shown below:
...
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1
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Custom component organization system
I'm rewriting an old Swing project that I did a few months ago, a fairly simple copy-cat of MS paint. I've been doing a pretty good job of keeping the code maintainable and organized, but I've hit a ...
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follow-up - caesar-cipher - java
I now processed the suggestions you can find here. I've deleted some duplications and corrected some other minor mistakes.
Here's the code:
...
user214772
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1
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Sudoku-Solver - follow-up
I've now tried to use the suggestions you can find here to improve my Sudoku-Solver.
Here's the updated code:
...
user214772
3
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1
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Date validation in Java
I'm learning Java, and would really appreciate any tips on how to improve this code.
It's just a simple date validation class.
...
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2
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BigRational based on BigIntegers
For Project Euler I've implemented a BigRational. The functionality is rather limited, just things I needed or will probably need soon. The style departs a bit from ...
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1
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Simple data structures for representing graphs in Java
Motivation
I do a lot of graph-theoretic code, and, by now, I feel substantial need for data structures that can represent weighted graphs, both directed and undirected. Up till now, I was in a habit ...
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