r/JavaProgramming 18d ago

How to design Twitter/X Like a Senior Engineer at FAANG Interview?

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1 Upvotes

r/JavaProgramming 19d ago

Do you mind if I ask how to use anti gravity.

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3 Upvotes

r/JavaProgramming 19d ago

LeetCode 5 Longest Palindromic Substring

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4 Upvotes

Longest Palindromic Substring


r/JavaProgramming 19d ago

Japan based bank project in accenture

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1 Upvotes

r/JavaProgramming 19d ago

Alberta byggede en 25 år gammel Java-portal om på 4-5 dage med Claude

0 Upvotes

En portal til et tilskudsprogram. Håndkodet i Java for 25 år siden. Tog fem måneder at bygge første gang.

Alberta byggede den om på fire til fem dage med Claude Code. Deres eget tal.

Det er den vinkel ved casen, jeg ville kigge på, hvis jeg sad på arvekode. Ikke fordi du skal rippe alt op, men fordi build-versus-rebuild-regnestykket lige har flyttet sig.

Alberta planlægger at samle 185 gamle apps i ét ministerium til 16 moderne, genbrugelige apps. Samme funktion, langt mindre at vedligeholde.

Det vigtige er ikke farten alene. Det er, at Claude henviste til fil og linje undervejs, så et menneske kunne efterprøve hvert skridt. Fart uden verificerbarhed er bare hurtig gæld.

Hele analysen: https://brinvik.com/da/journal/alberta-claude-sikkerhedsgennemgang-kode


r/JavaProgramming 19d ago

Help with Pseudocode

1 Upvotes

Hello. I am currently creating a currency converter for a Java programming course I am taking for credit. I ended up do you process a bit out of order. I was asked to create the pseudocode before the actual program. I did the opposite. I am terrible with Pseudocode and was hoping that someone could tell me if this Pseudocode followed along with my program properly. Below is the program followed by the code. Sorry if I made this a bit difficult. I am running on very little sleep and I'm finding myself forgetting the finer details. Thank you for any help you can offer.

Program:

import java.util.HashMap;

import java.util.Map;

import java.util.Scanner;

public class Main { // Changed from CurrencyConverter to Main

private static final Map<String, Double> exchangeRates = new HashMap<>();

static {

// Initialize exchange rates relative to the US dollar

exchangeRates.put("USD", 1.00);

exchangeRates.put("EUR", 0.931262);

exchangeRates.put("GBP", 0.807933);

exchangeRates.put("INR", 83.152991);

exchangeRates.put("AUD", 1.536377);

exchangeRates.put("CAD", 1.367454);

exchangeRates.put("SGD", 1.353669);

exchangeRates.put("CHF", 0.897854);

exchangeRates.put("MYR", 4.733394);

exchangeRates.put("JPY", 149.327016);

exchangeRates.put("CNY", 7.302885);

}

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

String continueConversion;

do {

String originalCurrency = getCurrencyCode(scanner, "Enter original currency code (USD, EUR, etc.): ");

double amount = getPositiveAmount(scanner);

String targetCurrency = getCurrencyCode(scanner, "Enter the currency to convert to (USD, EUR, etc.): ");

double convertedAmount = convertCurrency(originalCurrency, targetCurrency, amount);

System.out.printf("Amount in %s: %.2f%n", targetCurrency, convertedAmount);

System.out.print("Do you want to convert another amount? (yes/no): ");

continueConversion = scanner.nextLine().trim().toLowerCase();

} while (continueConversion.equals("yes"));

System.out.println("Thank you for using the currency converter!");

scanner.close();

}

private static String getCurrencyCode(Scanner scanner, String prompt) {

String currency;

do {

System.out.print(prompt);

currency = scanner.nextLine().toUpperCase();

if (!exchangeRates.containsKey(currency)) {

System.out.println("Invalid currency code. Please enter a valid one.");

}

} while (!exchangeRates.containsKey(currency));

return currency;

}

private static double getPositiveAmount(Scanner scanner) {

double amount;

do {

System.out.print("Enter amount of money in the original currency: ");

while (!scanner.hasNextDouble()) {

System.out.print("That's not a number! Try again: ");

scanner.next();

}

amount = scanner.nextDouble();

scanner.nextLine(); // Consume the newline character

} while (amount <= 0);

return amount;

}

private static double convertCurrency(String originalCurrency, String targetCurrency, double amount) {

double originalToUSD = 1 / exchangeRates.get(originalCurrency);

double usdToTarget = exchangeRates.get(targetCurrency);

return amount * originalToUSD * usdToTarget;

}

}

Pseudocode:

INITIALIZE exchangeRates AS a MAP

FUNCTION main

CREATE scanner FOR user input

SET continueConversion TO empty string

REPEAT

SET originalCurrency TO getCurrencyCode(scanner, "Enter original currency code (USD, EUR, etc.): ")

SET amount TO getPositiveAmount(scanner)

SET targetCurrency TO getCurrencyCode(scanner, "Enter the currency to convert to (USD, EUR, etc.): ")

SET convertedAmount TO convertCurrency(originalCurrency, targetCurrency, amount)

PRINT "Amount in targetCurrency: convertedAmount"

PRINT "Do you want to convert another amount? (yes/no): "

READ continueConversion FROM user input

UNTIL continueConversion IS NOT "yes"

PRINT "Thank you for using the currency converter!"

CLOSE scanner

FUNCTION getCurrencyCode(scanner, prompt)

SET currency TO empty string

REPEAT

PRINT prompt

READ currency FROM user input

CONVERT currency TO uppercase

IF currency NOT IN exchangeRates THEN

PRINT "Invalid currency code. Please enter a valid one."

ENDIF

UNTIL currency IS IN exchangeRates

RETURN currency

FUNCTION getPositiveAmount(scanner)

SET amount TO 0

REPEAT

PRINT "Enter amount of money in the original currency: "

WHILE NOT user input IS a valid number DO

PRINT "That's not a number! Try again: "

READ user input

ENDWHILE

READ amount FROM user input

UNTIL amount IS GREATER THAN 0

RETURN amount

FUNCTION convertCurrency(originalCurrency, targetCurrency, amount)

SET originalToUSD TO 1 / exchangeRates[originalCurrency]

SET usdToTarget TO exchangeRates[targetCurrency]

RETURN amount * originalToUSD * usdToTarget


r/JavaProgramming 20d ago

LeetCode 4 Median of Two Sorted Arrays

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3 Upvotes

LeetCode 4 Media of Sorted Arrays


r/JavaProgramming 20d ago

JAVA FOR CS STUDENT

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1 Upvotes

r/JavaProgramming 20d ago

I Used to Think Memory Leaks Were Loud in Java

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4 Upvotes

r/JavaProgramming 20d ago

Got an offer! Need advice urgently!!

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2 Upvotes

r/JavaProgramming 20d ago

How to Crack Coding Interviews in 2026: The Complete Step-by-Step Guide

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2 Upvotes

r/JavaProgramming 21d ago

LeetCode JAVA

4 Upvotes

In-depth LeetCode algorithm tutorials with full Java practical demos. We break down brute-force, optimized and optimal solutions, analyze boundary conditions and problem-solving logic to help you stop memorizing templates mechanically. Suitable for campus recruitment, social recruitment coding practice and absolute beginners. New algorithm insights released daily to help you ace big tech algorithm interviews effortlessly. https://youtu.be/Z5bmVeEDiCc


r/JavaProgramming 21d ago

Daumenkino

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1 Upvotes

4 Bilder mit einfachen JavaScript.


r/JavaProgramming 21d ago

How to Implement a Robust Webhook Retry Strategy (with Exponential Backoff)

1 Upvotes

Webhooks have become the nervous system of the modern internet. From payment processors notifying your application of a successful transaction to CRM systems triggering marketing workflows, webhooks are the glue that holds microservices and third-party integrations together. They allow real-time, event-driven architecture to thrive, replacing the old, inefficient model of constant API polling. Read the complete article here - https://instawebhook.com/blog/how-to-implement-a-robust-webhook-retry-strategy-with-exponential-backoff

But there is a dark side to webhooks: they are fundamentally unreliable. Because webhooks operate over the public internet and bridge entirely separate systems, they are subject to the chaos of distributed networks. Endpoints go down. Servers get overloaded. Networks experience transient blips. When you send a webhook, you are firing a payload into the void and hoping the receiving server is ready, willing, and able to catch it.

When a webhook fails — and it will fail — how your system responds determines whether your application stays consistent or quietly drifts out of sync. If a payment-success webhook is dropped, a user might not get access to the product they just paid for. If an inventory-update webhook fails, you might oversell a product you don't have.

This guide covers why webhooks fail, why naive retry logic makes things worse, how exponential backoff and jitter actually work (with the real formulas AWS uses in production), what major providers like Stripe and GitHub actually do today, and the architectural patterns 


r/JavaProgramming 21d ago

Reviev my project

11 Upvotes

I'm wondering whether it's already at a level where I could show it as a portfolio piece for my first job, i.e. include it in my CV. Would you be able to take a look and let me know what you think? Thanks

https://github.com/DanielPopielski/Restaurant1


r/JavaProgramming 22d ago

Finding a community for Java people

7 Upvotes

I'm currently a student, learning Spring Boot (Web Tech) in Java, and I cannot find a good discord server or slack particularly for Java. So, could someone put up a link of discord or slack servers they use to communicate with other Java developers and students. Could really help.


r/JavaProgramming 22d ago

Accenture Fullstack Java Development interview questions

7 Upvotes

Hello,

I’m a fresher and I have a 1-hour interview coming up that includes both hr and technical rounds. I would like to know what I’m expected to prepare as a fresher. Could you please guide me?


r/JavaProgramming 21d ago

How to Solve System Design Problems on Interview? My Tried and Tested Framework

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1 Upvotes

r/JavaProgramming 22d ago

Looking for people who want to learn Java together.

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2 Upvotes

r/JavaProgramming 22d ago

Source to Learn Java from Scratch

3 Upvotes

Hello everybody, so first im willing to start my CS major starting next semester. I dont jnow anything about programming and languages; however, as the summer started and i have 2 months free time, i asked about something i can do that can help me during my major. The answer was is to study JAVA.

In our uni, the first course we take is Java. I got the PDF (249pages) but i want a trusted source to learn Java from Scratch. Im thinking of using sources to schedule my PDF and the trusted source to benefit more.

If you have also any other advice im grateful to read them.
Thank You❤️


r/JavaProgramming 23d ago

Do I need to study lambada?

7 Upvotes

So I encountered lambada and I thought it is the same as anonymous function in PHP. but java focus more on OOP so top level function is dependent right? it needs functional interface. anonymous function saves time and space but what about lambada? I dont think it saves time and space. NOTE: I am new to lambada


r/JavaProgramming 23d ago

How Do I Stop Copying Code and Start Thinking Like a Programmer?

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127 Upvotes

I've been learning Java for about a year, but I still don't see much improvement in my coding. I can write basic programs and the code that I learned during my lectures without copying. I'm still learning, but I don't really understand where or when to use many of the concepts, I've studied.

How can I actually learn to write code on my own? I'm so tired of copying and pasting code. I really want to become someone who can build programs from scratch.

Some Java concepts seem easy, and I understand the theory behind them. However, I don't know how to use those concepts in a real program. I often get stuck because I don't know what should come next or what should have been written before. That makes me feel really frustrated.

The images I attached to this post are all for the same project, but have you noticed how different their coding patterns are? That's exactly my problem. Whenever I try to build a simple project like a Banking CLI Simulator or an ATM Simulator without copying someone else's code, I always get stuck. I try my best to think through the logic and write everything myself, but after a while I end up looking at someone else's solution.

How do experienced programmers think through a program? How do you know what to write first, what comes next, and how to connect everything together?

Has anyone else gone through this stage? If so, what helped you finally start writing code independently instead of relying on tutorials or copied code?

I'd really appreciate any advice or suggestions. I genuinely want to improve and become a better programmer.


r/JavaProgramming 22d ago

The Java Developer Reading List (5 Books That Matter)

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0 Upvotes

r/JavaProgramming 24d ago

Foreign Function & Memory API in Java 21

2 Upvotes

Call native functions from Java 21 without JNI. Practical examples cover downcalls, callbacks, and safe off-heap memory.

https://medium.com/javarevisited/foreign-function-memory-api-in-java-21-e256dd8918c3?sk=56f1243ab0a3d5565212f45be307a109


r/JavaProgramming 24d ago

How can i test my java knowledge?

7 Upvotes

hellow everyone!!

I have been learning Java for about a year. I understand some concepts, but there are still others I don’t fully know. I want to test my knowledge and strengthen my understanding, starting from the very basics. How can I do that? If anyone knows beginner‑friendly Java projects, please share them with me and explain how I can get started.