java-tutorial | 本项目是我个人在编写Java系列博客的源代码，会持续不断更新。如果项目中的代码有错误，望大家一起勘正。 | Microservice library

I have used java on many IDEs but I simply cannot on VS Code/linux. Before you tell me to just google it/remove my post, I've already read the similar stack overflow question, java tutorial VS Code, and setting java.home by oracle.The actual stack overflow post wasn't even answered even though it was marked solved.

I am running VS Code on windows and running all my coding in VSCode in a WSL, basically Ubuntu for windows. I installed the Java Extension Pack. I installed the jdk in my root directory and defined the path in settings.json as such

I'm using VS Code in WSL2 and have installed a bunch of Java Extensions as per this link - normal Java programs work well - able to Run & Debug from VS Code.

Although when I start using Java 8 specific features like Lambda, it starts complaining about the source level for Java

I've the following environment variables configured for Java Home

What property should be specified in Settings to determine the source level as 1.8 and not lower !

Edit: The bottom blue bar says the current Java Runtime is J2SE1.5 for some reason. See Attached

On clicking, it asks to add the following property: java.configuration.runtimes and so I've added the following in my WSL2 settings for VS Code - still no effect !

I'm using brew to build OpenCV with java support following this tutorial. After built successful I got the error class file has wrong version 57.0, should be 52.0 when using. I'm using OpenJDK 8, how can I target the build to this version. Thank you.

Been reading and watching escaping references and I get the idea of why and how to fix it, but I'm still confused on one thing...

What if the data does need to be updated? For example, I copied the code from the blog post down below and also added an additional class member of "email". Say the customer changed his email address. If this structure does not allow the object to be modified, how it the update done then?

Interface:

Right now I'm trying to develop a Java project with pure java (no builtscript). I'm implementing the module concept from Java 9. I'm having a trouble when it comes to run a Java project (main class) with additional jar file (third party library). I have no trouble when compiling but when I try to run the java it couldn't run as expected.

I could compile this project by executing this command (javaFiles.txt contains my java files that wanted to be compiled):

I am trying to reproduce this post.

this is a classic hello world in java, with additional package app;

I posted this question earlier.

But that wasn't quite the end of it. All the rules that applied there still apply.

So the strings:

• "%ABC%" would yield ABC as a result (capture stuff between percent signs)
• as would "$ABC." (capture stuff after $, giving up when another dollar or dot appears)
• "$ABC$XYZ" would too, and also give XYZ as a result.

To add a bit more to this:

• "${ABC}" should yield ABC too. (ignore curly braces if present - non capture chars perhaps?).
• if you have two successive dollar signs, such as "$$EFG", or "$${EFG}",
  that should not appear in a regex result. (This is where either numbered or named back- references come into play - and the reason I contemplated them as non-capture groups). As I understand it, a group becomes a non-capture group with this syntax (?:).

1) Can I say the % or $ is a non-capture group and reference that by number? Or do only capture groups get allocated numbers?

2) What is the order of the numbering, if you have ((A) (B) (C)). Is the outer group 1, A 2, B 3 C 4?

I have been look at named groups. Saw the syntax mentioned here

(?capturing text) to define a named group "name"

\k to backreference a named group "name"

3) Not sure if a non-capture group can be named in Java? Can someone elucidate?

• More info here on non capture groups.
• More info here on lookbehinds
• Similar answer to a question here, but didn't quite get me what I wanted. Not sure if there is a back-reference issue in Java.
• Similar question here. But could not get my head around the working version to apply to this.

I have used the exact same Java I had in my original question, except for:

I have a search string. When it contains a dollar symbol, I want to capture all characters thereafter, but not include the dot, or a subsequent dollar symbol.. The latter would constitute a subsequent match. So for either of these search strings...:

What are the basic structural aspects that should exist in Julia code I am writing? I will link some other language's implementation of this for reference.

I am looking for officially sanctioned components for the language itself, not one's opinion on best practices.

Basic Structure of a C Program

Basic Structure of a Java Program