From 576f9c9eafa17e9f3bb13e2c85d2ef4516620a3c Mon Sep 17 00:00:00 2001
From: exaucae <chrysexaucet@hotmail.fr>
Date: Fri, 11 Nov 2022 23:43:57 +0000
Subject: [PATCH] feat: print hello world with Java down calling C
---
java-panama/pom.xml | 46 +++++++++++++++++++
.../com/baeldung/java/panama/HelloWorld.java | 42 +++++++++++++++++
2 files changed, 88 insertions(+)
create mode 100644 java-panama/pom.xml
create mode 100644 java-panama/src/main/java/com/baeldung/java/panama/HelloWorld.java
diff --git a/java-panama/pom.xml b/java-panama/pom.xml
new file mode 100644
index 0000000000..ad711d0718
--- /dev/null
+++ b/java-panama/pom.xml
@@ -0,0 +1,46 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <groupId>com.baeldung.java.panama</groupId>
+ <artifactId>java-panama</artifactId>
+ <version>1.0-SNAPSHOT</version>
+ <packaging>jar</packaging>
+
+ <name>java-panama</name>
+ <url>https://maven.apache.org</url>
+
+ <properties>
+ <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+ <maven.compiler.source>19</maven.compiler.source>
+ <maven.compiler.target>19</maven.compiler.target>
+ <maven.compiler.version>3.10.1</maven.compiler.version>
+ </properties>
+
+ <dependencies>
+ <dependency>
+ <groupId>org.junit.jupiter</groupId>
+ <artifactId>junit-jupiter</artifactId>
+ <version>5.9.0</version>
+ <scope>test</scope>
+ </dependency>
+ </dependencies>
+
+ <build>
+ <plugins>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-compiler-plugin</artifactId>
+ <version>${maven.compiler.version}</version>
+ <configuration>
+ <source>${maven.compiler.source}</source>
+ <target>${maven.compiler.target}</target>
+ <compilerArgs>
+ <arg>--add-opens=java.base/java.lang.foreign=ALL-UNNAMED</arg>
+ <arg>--enable-preview</arg>
+ </compilerArgs>
+ </configuration>
+ </plugin>
+ </plugins>
+ </build>
+</project>
diff --git a/java-panama/src/main/java/com/baeldung/java/panama/HelloWorld.java b/java-panama/src/main/java/com/baeldung/java/panama/HelloWorld.java
new file mode 100644
index 0000000000..060a8552ef
--- /dev/null
+++ b/java-panama/src/main/java/com/baeldung/java/panama/HelloWorld.java
@@ -0,0 +1,42 @@
+package com.baeldung.java.panama;
+
+import java.lang.foreign.*;
+import java.lang.invoke.MethodHandle;
+import java.util.Objects;
+
+import static java.lang.foreign.ValueLayout.ADDRESS;
+import static java.lang.foreign.ValueLayout.JAVA_INT;
+
+
+public class HelloWorld {
+
+ public static void main(String[] args) throws Throwable {
+
+ String symbolName = "printf";
+ String greetings = "Hello World from Project Panama Baeldung Article";
+
+ Linker nativeLinker = Linker.nativeLinker();
+ SymbolLookup stdlibLookup = nativeLinker.defaultLookup();
+ SymbolLookup loaderLookup = SymbolLookup.loaderLookup();
+
+ FunctionDescriptor functionDescriptor = FunctionDescriptor.of(
+ JAVA_INT.withBitAlignment(32),
+ ADDRESS.withBitAlignment(64)
+ );
+
+ MethodHandle methodHandle =
+ loaderLookup.lookup(symbolName)
+ .or(() -> stdlibLookup.lookup(symbolName))
+ .map(
+ symbolAddress -> nativeLinker.downcallHandle(symbolAddress, functionDescriptor)
+ ).orElse(null);
+
+
+ Objects.requireNonNull(methodHandle);
+
+ try (MemorySession memorySession = MemorySession.openConfined()) {
+ MemorySegment nativeGreetings = memorySession.allocateUtf8String(greetings + "\n");
+ methodHandle.invoke(nativeGreetings);
+ }
+ }
+}