tag:blogger.com,1999:blog-67035151446500390492026-06-16T19:27:19.949+02:00javanot only java blogMiloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comBlogger63125tag:blogger.com,1999:blog-6703515144650039049.post-38515845537500981532025-10-15T08:43:00.005+02:002025-10-15T08:46:54.709+02:00What the hell is this? #:~: Have you ever seen (as a part of a URL) something like this?#:~:Well, that's something! This part of url is called URL Text Fragments. And it is very useful! How It Works?You certainly already know that, the # symbol (called a hash or fragment identifier) separates the main URL from a fragment that references a specific section of the page. Traditionally, # links to an element with a Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-38027673268080077982025-09-28T16:02:00.011+02:002025-09-29T13:45:24.262+02:00Revit - problém so zamŕzaním aplikácie (Windows 11 + SSD 1TB)Ste čerstvý študent na stavebnej fakulte, kúpite si nový nadupaný notebook (AMD Ryzen 9 8940HX, 32 GB RAM, SSD 1TB), veď potrebujete rýchle zviera, beštiu!Nainštalujete si Autodesk Revit a spustíte ho. Idete otvoriť prvý súbor - template od cvičiaceho a... nič!Vymrzol!Tak kill aplikácie a spúšťate znovu, otvoríte si nejaký projekt alebo template z inštalácie - tie idú všetky v pohode. Stiahnete Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-86658254689153889962025-05-12T11:34:00.001+02:002025-06-04T11:41:44.762+02:00Java 24 Experimental Features: Three Key InnovationsJava 24, released on March 18, 2025, introduces several experimental features that represent significant advancements in JVM technology. Among the 24 Java Enhancement Proposals (JEPs) included in this release, two are designated as experimental features. Here are the three most interesting experimental innovations in Java 24.1. Compact Object Headers (JEP 450)The Compact Object Headers feature Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-1040361812425103892025-04-03T11:14:00.035+02:002025-06-04T11:30:02.516+02:00Java 24 Release - March 2025Java 24 Release - March 2025Oracle released Java 24 on March 18, 2025, as the latest version of the Java SE Platform. This release represents the Reference Implementation of Java SE Platform version 24 as specified by JSR 399 in the Java Community Process.Key Features:Stream Gatherers: A new enhancement that gives developers fine-grained control over how elements are grouped and processed within Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-80469341823424796382025-03-31T14:40:00.004+02:002025-06-04T11:42:27.722+02:00Did you know that methods in Java have a size limit?The JVM's method size limit of 64kB of bytecode is an important constraint for Java developers to understand. Here's more information about this limitation:JVM Method Size LimitThe 65,535 (64K-1) byte limit on method bytecode is a fundamental constraint in the Java Virtual Machine (JVM) specification. This isn't about the number of lines of source code, but rather the compiled bytecode size of a Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-86463300824645394382025-02-21T10:53:00.008+01:002025-06-04T11:42:42.687+02:00Customizable HTML tag: select/optionÓ, HTML bože, wwwládca webapp neba, vďaka! Na toto som čakal roky (desiatky rokov). Kto pracuje s web technológiami, kde sa používa HTML, isto neraz zaklial, keď musel použiť klasický, hmm, nazvyme ho ”combobox”. HTML tag <select> s jeho položkami <option> je štýlovateľný asi tak, ako chcieť urobiť z trabanta mercedes. O jeho funkcionalite ani nehovoriac. Preto bolo vždy Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-38655835976525270162024-08-26T09:54:00.000+02:002024-08-26T09:54:08.501+02:00My, ľudia, sme veľmi namyslení.Myslíme si, že sme ktovieako inteligentní. Nedokážeme jednoducho a rýchlo zrátať z hlavy ani dve trojciferné čísla. Nerozoznáme margarétku od sedmokrásky. Nevieme sa dohovoriť s človekom hovoriacim iným jazykom, dokonca niekedy ani cez plot s vlastným susedom.AI väčšinu z toho dnes zvláda ľavou zadnou (ak by ju mala) a dosiahla to iba za niekoľko rokov. Stačilo len trochu viac výpočtového výkonu.Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comDolná 15, 974 01 Banská Bystrica, Slovensko48.7339746 19.143237648.733266973857745 19.142164716394042 48.734682226142262 19.144310483605956tag:blogger.com,1999:blog-6703515144650039049.post-77728981852308110342023-06-20T15:15:00.004+02:002023-06-27T11:56:29.063+02:00What is the minimum app in Java (21)?Who doesn't know "Hello, World!"? When you start writing a code in a new language, you usually write this simple program. What does it look like in Java code?
class App {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
But, explain to a beginner what "public static void" and strange args are. What would you say if the program could be Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-52830042627211291552023-04-26T14:02:00.009+02:002023-06-20T13:40:12.038+02:00False is trueIs flase true? Or true is false...
Let's find out together.
public class J {
public static void main(String args[]) {
if (true == false) {
// some unicode: \u000a\u007d\u007b
System.out.println("true is false! realy?");
}
}
}
This short java code prints out message "true is false! realy?". Why? Just look at the unicode characters in the comment. What Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-86232734769160335172023-04-25T08:57:00.003+02:002023-05-22T15:40:44.947+02:00Will this Java code run?Will this Java code run? The Test instance variable via the value() method returns null. What about NullPointerException? Is it possible to access the pi member through null?public class Test { static float pi = 3.14f; Test value() { return null; } public static void main(String args[]) { Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-56753283148892532592022-10-03T15:16:00.001+02:002023-05-22T15:41:14.448+02:00A Joke About Java ProgrammersQ: What will happen to the old senile Java programmers?A: Nothing, they just lose some of their functions.Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-7254850723604066092022-03-30T13:10:00.003+02:002022-03-30T13:16:18.337+02:00JavaOne is back!In 2018 and 2019, the famous Java developer conference used the name Code One. For 2022, the name JavaOne is back again! The world's leading developer conference is scheduled to take place in Las Vegas at Oracle CloudWorld in October 2022.Oracle CloudWorld promises to keep you up-to-date on Java innovations in 2022. News on development tools, resources and best practices to accelerate the Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-27438762954526853752020-09-30T12:00:00.105+02:002023-05-26T12:22:35.184+02:00Text BlocksOd Java 15 sú textové bloky k dispozícii ako štandard. V Java 13 a 14 je potrebné túto feature povoliť (preview).Zatiaľ posledná verzia platformy Java je ver. 15, alebo keď chcete presnejšie JDK 15 rel. 2020-09-16. Posledná LTS (verzia dlhodobej podpory) bola JDK 11 zo septembra 2018.Text BlocksAj vy máte problém s tým, keď máte dlhý String a potrebujete ho dať do premennej priamo v kóde? Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-56396194544248870982020-09-09T11:02:00.008+02:002023-06-21T10:47:23.821+02:00Java block as a class memberDo you know code block? Of course you know! Block of code defines the scope of variables and puts more statemets together. But what about non-static blocks as a class member? You can put them as other class members such as static blocks, class variables and methods.E.g. static block is executed after class is loaded. This example is clasic block of code...
{
// block of statements: Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-79177693090309886412019-06-12T11:31:00.001+02:002020-02-12T12:35:58.658+01:00Really Strange Java Code (Really?)
If you put URL directly into your java code, it can be compiled.
The protocol "http:" is interpreted as a label (used to jump into) and rest, behind the slashes "//" is considered as a comment.Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-33717537646739310632018-06-06T12:20:00.002+02:002023-06-05T11:39:42.336+02:00Java 8 interface default method does not declare the propertyImplementing default interface method, don't expect clasic property in implementing class. This is a Java bug.
When retrieving the properties from some java bean the introspector does not return the properties defined by getter/setter default methods in an interface implemented by the bean.
Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-57328777071977110252015-09-26T16:16:00.026+02:002023-06-05T11:40:53.342+02:00Java 9 countdownCountdown to Java 9 Release DateWhat are the most exciting features expected in Java 9?
Java + REPL (Read-Eval-Print-Loop) = jshell
If you are gonna run a few lines of Java you won’t have to wrap them in a separate project or a method.
Microbenchmarks are coming
The Java Microbenchmarking Harness (JMH) by Alexey Shipilev is taking the next step in its evolution.
Default GC
Java hasMiloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-3317895664562725712015-02-28T14:15:00.000+01:002015-03-16T14:20:34.971+01:00Java 8 / did U know?
JavaScript engine
Engine Nashorn replaces old one (Rhino) as the new default JavaScript engine for the Oracle jvm. Nashorn is faster. It uses the invokedynamic feature of the jvm. "jjs" is Nashorn command line tool.
Optional
8 comes with the Optional class (java.util.Optional) for avoiding nulls (NullPointerException). It is very similar to Google’s Optional, which is similar to Nat Pryce’s Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-35832401476017065232015-02-04T13:20:00.002+01:002023-06-05T11:41:42.246+02:00Get Enum constant of an Enum by StringMethod cast(Class, String) builds the enum value constant of the specified Enum. The name must match exactly (case) an identifier used to declare an enum constant in the given Enum.
@SuppressWarnings({ "rawtypes", "unchecked" })
public static <E extends Enum<E>> E cast(String name, Class&lt;E> clazz) {
if (clazz == null || name == null || name.isEmpty()) {
return Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-48047589007662987852014-11-19T22:19:00.003+01:002014-11-19T22:19:58.248+01:00Antix SMTP
Antix SMTP is awsome smtp server for developers. This allows you to configure and test the way SMTP servers work. You can create multiple hosts and ports. This fake SMTP server do not send emails actually, it's only for testing.
Main features:
Fake - will not actually send e-mails, no risk of accidentally e-mailing to a client
Testable - you can create the server in code, thenMiloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-61413176063165475302014-07-04T15:36:00.000+02:002014-07-04T15:36:00.604+02:00How to manually add new jdk to gentoo
#list available JDKs
java-config-2 -L
#download and unpack tgz from oracle, eg oracle-jdk-1.7
/opt/oracle-jdk-1.7
#link-to /opt/oracle-jdk-1.7
/usr/lib/jvm/oracle-jdk-1.7
#create file /usr/share/java-config-2/vm/oracle-jdk-1.7
VERSION="Oracle JDK 1.7.0"
JAVA_HOME=/opt/oracle-jdk-1.7
JDK_HOME=${JAVA_HOME}
JAVAC=${JAVA_HOME}/bin/javac
PATH="${JAVA_HOME}/bin:${JAVA_HOME}/jre/bin"
ROOTPATH="${Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-56668002199458577842013-03-04T13:03:00.000+01:002013-03-04T13:05:40.234+01:00How to manually install packageWhen you corrupt your portage or something is wrong with your installation,you can manually download a package, compile and install it...
Packages are located at http://mirrors.kernel.org/gentoo/distfiles
Code:
cd /usr/src
wget http://mirrors.kernel.org/gentoo/distfiles/PACKAGE-x.y.z.tar.bz2
tar -xf PACKAGE-x.y.z.tar.bz2
cd PACKAGE-x.y.z
./configure --prefix /usr
make
make Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-49143786348219298062012-06-06T08:29:00.003+02:002012-06-06T08:30:35.257+02:00Util to decode multilogstail -f /var/.../current | tai64nlocal
but if you want to see e.g. in tinydns IP addresses, use next script...
#!/usr/bin/perl -w
#A program to decode tinydns logfiles
#Written by Sean Hunter
#Copyright (c) 2001 Uncarved Systems Ltd
#
#This is free software released under version 2
#of the GPL without warrantees of any kind
use strict;
use IPC::Open2;
#Requires djb's tai64nlocal to Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-52557658088855611972012-05-13T18:41:00.000+02:002012-05-13T18:41:43.902+02:00JAVA 7: Underscores in Numeric LiteralsIn Java 7 an underscore characters (_) can be put anywhere between digits in a numeric literals. If application code contains numbers with so many digits, you can use an underscore character to organize digits to the groups of three, four or as much as you want. This absolutly improves code readability.
Examples:
long myPayment = 1_234_567L;
long phoneNumber = Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.comtag:blogger.com,1999:blog-6703515144650039049.post-11336190085861683962012-05-10T13:50:00.000+02:002012-05-10T13:50:50.954+02:00LG panel L245WP HDMI display problemIf you have the LG panel L245WP-BN and have it connected over HDMI to an NVIDIA card under Windows Vista/7, you may encounter a problem where the image at resolution 1900x1200 is cropped and off-center.
Here is the solution http://www.voetsjoeba.com/misc/edid/Miloš Bielikhttp://www.blogger.com/profile/18445116125660716034noreply@blogger.com