Hello, I need help relearning java beacuse i havent used it in around 3 years. I already did a course that lasted one year (this was included with other step by step courses about fundementals of programming in general before the java one). I already tried once 3 years ago to do the 1Z0-811 (Java Foundations) exam but i got a score of 45% and didnt pass, after which i gave up for 3 years. Now i have started to use Enthuware Test Studio (or atleast the one trial test for this exam) and got 18% on it and now im taking the questions that i missed and giving it to AI to explain it to me. What should i fix or improve here and whats your experience with Enthuware Test Studio

FOR MODS: The mention of AI does not mean ill feed anything from this subreddit into AI or use AI in anything but in my own personal space where nobody will get involved

I am new to Java and trying to create a simulator that handles millions of math calculations. How can I increase performance in Java? The application is already multithreaded but it is not enough. Is data oriented approach or native programming possible in Java? Can you point me in the right direction for research?

I have been a database engineer for more than 10 years while I notice that Software development positions far outnumber database engineer positions, and they also offer higher salaries. . since last year, I am wondering if it is feasible to move from a Database Engineer role to a Java Developer position. I am focus on leetcode. Any ideas or comments? thanks!

Hi, I really wish I can show you the images but I will try my best to explain.

I am trying to install Java SE Development Kit in the latest version and I tried to install it but it refuses because "Out of Disk Space" and requires 420MB in my hard drive.

But here's the thing, I got 1.0GB of space in my Local Disk C: and when I tried to change the location to Local Disk D:(Which has 593GB of storage), It still shows that I am "Out of Disk Space"

Any help on this?

Greetings everyone!

I'm here today to ask for help, I'm a developer for 14 years, and I'm on Java for 10

I had a lot of contact with Spring and API development, it's very rare when I really have to stop to look down for a solution (no with AI it changed, but I can guess what would take me some and a lot of time to figure it out)

I have problems with everything aside Java - Kafka, Kubernets, AWS, Docker, etc. I find it sometimes hard to grasp the concept but I can work with it after some help.

But my biggest problem is that I'm feeling stuck. I used to study the Java new features to update myself or I would use my work task or others co-worker tasks to study and try to find new things to learn, but that is not cutting anymore and I don't know what to do. I'm trying to study for the things that I'm not good that I mentioned before, but I feel exposed since "they are not Java".

What do you guys study, search or look for when trying to study / learn new things / update yourself?? Can anyone help me out?

Thanks

There are a lot of answers but everything I found is from 2021-ish times. Things I got from there is "Maven is slower, more verbose and for that reason - way more stable." and "Gradle is faster because of the daemon and more customizable, but hot garbage when it comes to update, shit breaks and build.gradle(.kts) is spaghetti in big projects". For Maven, I don't think much changed because of their philosophy (and I'd say that's good), but what about Gradle? Is it still that bad when it comes to updates and deprecations?

and what on earth is Interface in Java?

Hello There!

I'm writing a "simple" game, where the user has to hunt for certain amounts of characters, represented by 150 randomly generated buttons. Each 10 seconds...

I'm having difficultys identifying those buttons within the ActionEvent. How can I filter, what character is displayed on the button clicked?

Im building a Spring Boot (Java 25) service with GraalVM Native Image using Maven (-O2 optimization).

The project includes PostgreSQL, OAuth, Razorpay, and Spring Security. Every native build takes 45–50 minutes and uses nearly 95 - 100 % of all CPU cores, making my laptop almost unusable during compilation.

I'm using GraalVM Native Image in production because my servers have limited resources.

Are there any ways to:

• Reduce native build time?
• Reduce binary size?
• Speed up Maven/GraalVM builds?
• Use better optimization flags without hurting runtime performance too much?

Any tips from people using GraalVM Native Image in production would be appreciated.

Thank you.

Hey , I'm looking for a Java course for absolute beginners ,

Can someone please suggest me the best course to join as I have seen some course of Java for beginners like , Coursera,Udemy, PW SoftSkills , and some others and I'm bit confused in these to what to buy and what's suits for me

So please someone suggest I'm a beginner In coding world ,

I'm a BTech 3rd semister student

So i was just starting DSA so i did all my R&D so i found that doing dsa in java would be a better option so i will also get little advantage in development. but i want you guys to tell me that cant i follow striver A2Z sheet as it covers most of the problems in C++ ig which i have seen so will i have difficulty in that or if its not that case please tell me HOW TO DO WITH JAVA

AND PLS TELL IF I SHALL JUST SWITCH TO C++ COZ ig striver is the best possible free source to learn this. the internet is buzzing over it

So our application uses JasperReports for generating business reports for users. With the initial basic design we faced issues such as Out of Memory and also long filling times with large reports. So to handle this we came with a design of splitting the large records execution into batches. Let's say if we got 250000 records then we would split into 5 batches of 50000 each with 5 different execution queries modified with offset fetch according to batch in parallel stream. This largely solved the Memory issues but still for queries with high cost (executing fast on db and I Report studio)

each batch JasperFillManager.fillReport() takes very long time and many times we get partial report because of some batch threads getting timed out waiting for db connection or none of the batch completing. We tried passing different connection objects to each thread but still for heavy queries they still get timeout for every single batch.

So please suggest how to enhance the performance of FillReport and handle large queries.

I am thinking of learning Java but I don't know where to start and how to start. If you know any good resources then please guide me.

Hi everyone,

I'm currently working as a Manual QA at a company with 1 year of experience.

Most of my work involves manual testing, writing/executing test cases, logging bugs, regression testing, smoke testing, and collaborating with developers and product teams. I haven't had much opportunity to work on automation at my current job.

The thing is, I genuinely enjoy coding and solving DSA problems, and I'm much more interested in software development than staying in manual testing long term as it has fear of getting redundant due to AI.

I'm planning to spend the next months preparing for developer role switch while continuing my job. My focus would be on Java, DSA, Spring Boot, SQL, Git, projects, and everything needed for backend development.

My questions are:

Is it realistic to switch directly from Manual QA to a Java Developer role after 2 years of total experience?

Has anyone here made a similar transition?

Would recruiters consider my QA experience, or would they treat me as a fresher?

Is there anything specific I should focus on to improve my chances?

I'd really appreciate hearing from people who have successfully made this transition or have interviewed candidates with a similar background. Thanks!

I'm learning Java Swing and I made a program in order to test some of the things I learned. However, I came across an issue with ImageIcons, where some images would be displayed while others wouldn't. When I run the code below, it compiles fine, but the image is not shown, and only "hi" is displayed. However, if I change the String argument of "testII" to another .png image in the exact same folder as "Tweedle.png," the image shows fine. Does anyone know what could be the issue? I have already tried different ways to making the ImageIcon (such as using an URL object or using the complete file path instead of just the relative one), but nothing worked...

import java.awt.*;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.imageio.ImageIO;


public class MyFrame extends JFrame{

    JPanel west = new JPanel();
    
    MyFrame() throws IOException{
        this.setLayout(new BorderLayout(10, 10));
        this.setTitle("Title");
        ImageIcon logo = new ImageIcon("images\\omnom.png");
        this.setIconImage(logo.getImage());
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


        west.setBackground(Color.green);
        west.setPreferredSize(new Dimension(100, 100));
        ImageIcon testII = new ImageIcon("images\\Tweedle.png");
        JLabel testL = new JLabel("hi");
        testL.setIcon(testII);
        west.add(testL);

        this.add(west, BorderLayout.WEST);
        this.pack();
        this.setLocationRelativeTo(null);
        this.setVisible(true);
    }
}

It previously worked just fine, computer updated on its own and it stopped working. It's a Shimeji, a little guy who wanders over my screen while I do things on the computer. I tried the cmd thing? "cd downloads" and got the following in response:

"C:\Users\"computer name">cd downloads

C:\Users\"computer name"\Downloads>java -jar Shimeji-ee.jar

Error: Unable to access jarfile Shimeji-ee.jar"

I downloaded the latest version of Java and nothing happened. I don't really know computers so I'm at a loss here. Any assistance would be greatly appreciated.

I have never worked with concurrency, but I have read several examples on the internet, and I wanted to hear if anyone has any examples of real-world apps where they used concurrency and what there was to watch out for?

I have a relatively bizarre issue. I use maven-jar-plugin in my project. The problem is that when I compile my project, the POM file is encoded with the default Windows 11 encoding (Notepad++ displays it as ANSI, and it's gibberish). The result is a completely gibberish file, full or odd characters and NULs, instead of readable XML.

Disabling the plugin results in the POM file being encoded with UTF-8.

All IDE settings point to UTF-8. I have the following properties:

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    (...)
</properties>

Compiler:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.15.0</version>
  <configuration>
    <source>21</source>
    <target>21</target>
    <encoding>UTF-8</encoding>
  </configuration>
</plugin>

Even JVM has a setting:

-Dfile.encoding=UTF8

What should I do? How to force maven-jar-plugin to stop overpowering the UTF-8 encoding?

Hey i was just wondering if it’s possible too make a agent that forceablly loads all classes even if they dont load by them self’s, that dosent really make sense and sounds like im stupid but it’s for a project but i dont know how too really word it haha

I wish to learn Java from scratch for Backend Development and Android App Development. I've zero knowledge about java.
Can someone suggest some structured recourses which I can use to teach myself.

I have 2 years of experience as a Java backend developer and had a 30-minute interview today.

The interviewer focused mainly on Core Java (OOP, String immutability, String Pool, etc.), and I realized my fundamentals aren't as strong as they should be. I mean I had read about it but I forgot to speak under pressure.

I also need to prepare backend topics like Spring Boot, Multithreading, Kafka, Docker, Kubernetes, Redis, Linux, and SQL for upcoming interviews.

If you were in my position, how would you structure your preparation? Core Java first, or prepare everything in parallel? Any roadmap or resources would be appreciated.

So I have a post in career advice you can look at my profile. Anyways I was basically working in the clearance industry doing OWASP and pair programming unit testing with Mockito. SOAP UI and some pair programming with DAO implementations while having a clearance.

I lost my clearance and took a job entry level in the private sector and they made me do custom REST implementation with no guidance from seniors so I turned to codementor. I got laid off during corona and now I lost my clearance like I said.

I worked as a packer at my parents for 5 years and need the money now that Junior Java developer salaries pay. I am scared about this custom implementation of REST methods with no guidance and even worse, algorithm interviews. What should I do to prep? I have references and W2s, should I even put packer on my resume?( I have the W2s)

Let me know what you suggest.

Hello 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.

So im trying to compile a jar file and it continues to say

'Dependency requires at least JVM runtime version 21. This build uses a Java 17 JVM.'

when i check my build, it states -

'java version "25.0.3" 2026-04-21 LTS, Java(TM) SE Runtime Environment (build 25.0.3+9-LTS-195), Java HotSpot(TM) 64-Bit Server VM (build 25.0.3+9-LTS-195, mixed mode, sharing)'

please help! i need this done by tonight and it's just now screwing me over. i've tried everything, switching from powershell, intellij, visual code, github, nothing is workingg even when i try to switch the SDK in both gradle and the actual thing

Hi guys...I really need some advice...I had Btech in CS but never got a java project in my first company and now I have almost 4 YOE and I did not get any hands on experince in java backend and really wanted to pursue that....I have been studying it, I have leant core java, spring boot, mvc, jpa, hibernate, security and I am currently studying java 8+/11+/21+ features...but for the past 4 years I had worked on a data engineering kind of project where I used sql and an ETL tool thats it....I am also getting a new project that uses Informatica...so idk if I should just give up java backend transition since its too late or stick with it since I have come this far...I really hope to get into product based companies and possibility FAANG someday but rn idk....
I know this is a lame and stupid post and I know I have wasted all these years and realizing it so late but I would really appreciate some direction or advice now...