Right click on src directory and select option Mark Directory As > Sources Root.
By setting the flag -XX:+PrintCompilation we can enable some simple output regarding the bytecode to native code compilation.Whenever a method is compiled, a line is printed to the output. Each line consists of (1) a number of milliseconds since VM started, (2) order in which method/code block is compiled, (3) compilation level cache, (4) method name.
java -XX:+PrintCompilation Mainval 1
val 2
val 3
...
922 315 3 src.main.BasicHolder::getInstance (4 bytes) # Method compiled
922 316 3 src.main.BasicHolder::getVALUE (4 bytes) # Method compiled
...
val 1563
val 1563
val 1563
val 1563
...... you can see in the 2nd column, and there is the percentage(%) symbol in front of some code blocks. That means those code blocks are in the code cache.
In the 3rd column, you can see the stages of the code block's compilation process. Some are in level 0, which are not compiled by the JIT compiler. That means code blocks that are not re-occurred. Some code blocks are in levels 1,2, and 3, which are compiled by the C1 compiler, and some are in level 4, which are compiled by the C2 compiler.
If you want to see the same information on some remote machine where you cannot see the console output you can use the following command:java -XX:+UnlockDiagnosticVMOptions -XX:+LogCompilation <class name>which will produce log file with compilation results in it.
You can enable a lot of debug information about how the compiler decides what to do with your code using feature flags like -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining
-Dfoo.bar=foobarclass Foo {
private static final String BAR;
static {
String foobar = System.getProperty("foo.bar");
if(foobar != null && foobar.length()>0) {
BAR = foobar;
} else {
BAR = "somedefaultvalue";
}
}
}-Duser.language=de
-Duser.country=DEWhen the JVM starts it search’s for this environment variable, and uses it. You can check the output of the JVM displaying a message with the values found.
export JAVA_TOOL_OPTIONS=‘-Dvar1=value1 -Dvar2=value2’
Arquillian is a container-agnostic integration testing framework for Jakarta EE.
- Jakarta EE applications deployed on an application server like Glassfish or JBoss- Servlet containers deployed on Tomcat or Jetty- Standalone containers- OSGI containers
<!-- Arquillian 1.7.0 adds Jakarta EE 9 and JUnit 5 support--> <arquillian-bom.version>1.7.0.Alpha10</arquillian-bom.version> <dependency> <groupId>org.jboss.arquillian</groupId> <artifactId>arquillian-bom</artifactId> <version>${arquillian-bom.version}</version> <scope>import</scope> <type>pom</type> </dependency> <dependency> <groupId>org.jboss.arquillian.junit5</groupId> <artifactId>arquillian-junit5-container</artifactId> <scope>test</scope> </dependency>
import org.jboss.arquillian.container.test.api.Deployment;import org.jboss.arquillian.junit5.ArquillianExtension;import org.jboss.shrinkwrap.api.ShrinkWrap;import org.jboss.shrinkwrap.api.asset.EmptyAsset;import org.jboss.shrinkwrap.api.spec.JavaArchive;@ExtendWith(ArquillianExtension.class)public class GreetingServiceTest {@Deploymentpublic static JavaArchive createDeployment() {return ShrinkWrap.create(JavaArchive.class).addClass(GreetingMessage.class).addClass(GreetingService.class).addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml");}@InjectGreetingService service;@Test@DisplayName("testing buildGreetingMessage")public void should_create_greeting() {var message = service.buildGreetingMessage("Jakarta EE");assertTrue(...);}}
java.lang.IllegalArgumentException: No enum constant org.jacoco.agent.rt.internal_c13123e.core.runtime.AgentOptions.OutputMode.fıle
-Duser.language=en
.\gradlew -Duser.language=en build
.\gradlew ...
.\gradlew build -x test
.\gradlew -Duser.language=en build
allprojects {
gradle.projectsEvaluated {
tasks.withType(JavaCompile) {
options.compilerArgs << "-Xlint:unchecked" << "-Xlint:deprecation"
}
}
}
The “buildscript” block only controls dependencies for the buildscript process itself, not for the application code, which the top-level “dependencies” block controls.
buildscript {
repositories {
google()
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.1.1'
}
}But what does that block do? Basically it defines dependencies which are required for the build itself. Or in other words: It defines dependencies which are required to build your Application (whatever your “Application” is (Android App, Gradle Plugin, Swift Desktop Application…)).In our Android example we have to define the Android Gradle Plugin dependency which helps us to build an APK:
The “new” plugins block is not really new. It was already introduced in Gradle 2.1.But there are some “limitations”. By default the plugin block can only resolve plugins which are either:- Core Plugins (provides by Gradle themself). These are e.g.: org.gradle.java, org.gradle.groovy, org.gradle.java-gradle-plugin and so on…- Published to the Gradle Plugin Portal.
plugins {id 'ear' }
plugins {id 'org.springframework.boot' version '2.1.2.RELEASE' }
configurations {compileOnly {extendsFrom annotationProcessor}}repositories {mavenCentral()}dependencies {implementation 'org.springframework.boot:spring-boot-starter-data-jpa'implementation 'org.springframework.boot:spring-boot-starter-data-rest'implementation 'org.springframework.boot:spring-boot-starter-web'compileOnly 'org.projectlombok:lombok'runtimeOnly 'com.h2database:h2'annotationProcessor 'org.projectlombok:lombok'testImplementation 'org.springframework.boot:spring-boot-starter-test'}
task hello {doLast {println 'Hello Baeldung!'}}
// Task for building the zip file for upload
task buildZip(type: Zip) {
// set the base name of the zip file
from compileJava
from processResources
into('lib') {
from configurations.runtimeClasspath
}
}
build.dependsOn buildZipapply from: "$rootDir/gradle/utils.gradle"What are Java Agents?, they are basically Java libraries that include classes that implement the Java Instrumentation API. Which is available since JDK 1.5. This is a very simple API but at the same time, very powerful. It lays the foundation for application instrumentation.The main functionality of this instrumentation is that it will allow us to add code to certain classes. And with this addition, we will be able to recompile data to be used mainly for monitoring and analysis or event logging purposes. Allowing us to obtain vital information about the application, that can help us to solve problems or obtain data that would not be possible otherwise.The main quality of this instrumentation API is the alteration of the byte-code of the classes that are being executed by the virtual machine. Through this alteration, we will be able to perform the actions previously indicated.