Ref.
Tools
Setting
* JAVA_HOME=C:\sdk\Java\jdk_1.8.0_65
* JDK_HOME=%JAVA_HOME%
* JRE_HOME=%JAVA_HOME%
* ----------------------------------
* Windows: PATH=%JAVA_HOME%/bin
* Linux: PATH=$PATH:$JAVA_HOME/bin
taskkill /f /im jqs.exe
taskkill /f /im javaw.exe
taskkill /f /im java.exe
Installing Java
Releases
* JDK 25 (GA 2025.09.xx) LTS
* JDK 24 (GA 2025.03.18)
* JDK 23 (GA 2024.09.17)
* JDK 22 (GA 2024.03.19)
* JDK 21 (GA 2023.09.19) LTS <<<===
* JDK 20 (GA 2023.03.21)
* JDK 19 (GA 2022.09.20)
* JDK 18 (GA 2022.03.22)
* JDK 17 (GA 2021.09.14) LTS
* JDK 16 (GA 2021.03.16)
* JDK 15 (GA 2020.09.15)
* JDK 14 (GA 2020.03.17)
* JDK 13 (GA 2019.09.17)
* JDK 12 (GA 2019.03.19)
* JDK 11 (GA 2018.09.25) LTS
* JDK 10 (GA 2018.03.20)
* JDK 09 (GA 2017.09.21)
* JDK 08 (GA 2014.03.18) LTS
Settings
sudo update-alternatives --config java
sudo update-alternatives --config javac
fedora
sudo dnf install java-17-openjdk-devel ## JDK
sudo dnf install java-17-openjdk-headless ## JRE-Min
sudo dnf install java-17-openjdk ## JRE-Full
Ubuntu
sudo apt install default-jre ### JRE
sudo apt install default-jdk ### JDK
----
sudo apt install openjdk-17-jre ### JRE
sudo apt install openjdk-17-jdk ### JDK
macOS
brew install openjdk@21
brew install openjdk@17
brew install openjdk@11
brew install --cask corretto
#########################################
brew list --versions openjdk@21
brew unlink openjdk@21
brew link --force --overwrite openjdk@21
Settings
-Xms1g ### Setting the initial and minimum heap size for 1G.
-Xmx1g ### Setting the maximum heap size for 1G.
-XX:+PrintGCDetails ### Detaillierte GC Logging.
-XX:+PrintGCDateStamps ### Jeder Zeile eine absolute Datums- und Zeitangabe vorangestellt.
-Xloggc:file.log ### Das GC Log wird in der Datei <file.log> geschrieben.
Maven
wget https://www-us.apache.org/dist/maven/maven-3/3.6.3/binaries/apache-maven-3.6.3-bin.tar.gz
sudo tar xzf apache-maven-3.6.3-bin.tar.gz
sudo ln -s apache-maven-3.6.3 maven
sudo vi /etc/profile.d/maven.sh
-------------------------------------
export MAVEN_HOME=/opt/maven
export PATH=${MAVEN_HOME}/bin:${PATH}
-------------------------------------
source /etc/profile.d/maven.sh
mvn -version
mvn archetype:generate
-DgroupId=net.samerhijazi
-DartifactId=maven-startup
-DarchetypeArtifactId=maven-archetype-quickstart
-DinteractiveMode=false
mvn clean
mvn compile
mvn package
mvn dependency:list-repositories
mvn dependency:tree
mvn dependency:analyze
mvn dependency:copy-dependencies
mvn dependency:get -Dartifact=com.google.protobuf:protobuf-java:3.19.1
mvn dependency:get -Dartifact=org.apache.maven.plugins:maven-downloader-plugin:1.0
Code-Collections
import java.util.concurrent.TimeUnit;
---------------------------------------------
try {
TimeUnit.SECONDS.sleep(secondsToSleep);
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
}
---------------------------------------------
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import io.agroal.api.AgroalDataSource;
public class SettingDatabase{
AgroalDataSource dataSource;
String db = "jdbc:db2://localhost:5245/DATABASE:user=db2;password=db2;";
String sql = "SELECT * FROM users";
public void init_DriverManager()throws SQLException{
try{
Connection connection = DriverManager.getConnection(db); //Connection connection = AgroalDataSource.getConnection(db);
PreparedStatement ps = connection.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
}
}
}
Architekture
Database
- JDBC is a low level standard for interaction with databases. JPA is higher level standard for the same purpose.
- JDBC allows you to do more things with the Database directly. JPA allows you to use an object model in your application.
- Datasource & Pooling (JDBC) >> Agroal
- Datasource & Pooling (Reactive) >> Vert.x
- Agroal is a datasource connection pool implementation with integration with transaction, security and other systems.
- Agroal library allows the definition of java.sql.DataSource with connection pooling.
- JPA (Java Persistence API) & Hibernate ORM (Object-relational mapping). JPA is only a specification. Hibernate is an implementation of JPA.
RESTFul
- RESTEasy is an implementation of JAX-RS and it is used to implement RestFul-services.
- Microservices communicating either synchronously via REST or asynchronously using Kafka.
Sprin Boot
