added example Java 18

Author: wesleyegberto

README.md

@@ -13,7 +13,7 @@ A project to explore more about the new features of Java 8, 9, ...
   * Pattern matching for `switch` (preview 2)
   * Deprecated method `finalize`
 
-* [Java 17](java-17/)
+* [Java 17](java-17/) (Sep, 2021)
   * Sealed classes (standard)
   * Enhanced Pseudo-Random Number Generator
   * Deprecate the Applet API for Removal
@@ -40,7 +40,7 @@ A project to explore more about the new features of Java 8, 9, ...
   * Foreign-Memory Access API (incubator)
   * GCs ZGC and Shenandoah turned final
 
-* [Java 14](java-14/) (May, 2020)
+* [Java 14](java-14/) (Mar, 2020)
   * Switch expression (standard)
   * Pattern matching for `instanceof` (preview)
   * Text blocks improvements (preview 2)
@@ -49,7 +49,7 @@ A project to explore more about the new features of Java 8, 9, ...
   * Packaging tool
   * JFR even streaming
 
-* [Java 13](java-13/)
+* [Java 13](java-13/) (Sep, 2019)
   * Switch expression (preview 2)
   * Text blocks (preview)
   * String API updates
@@ -58,28 +58,28 @@ A project to explore more about the new features of Java 8, 9, ...
   * Dynamic CDS Archives
   * ZGC: Uncommit Unused Memory
 
-* [Java 12](java-12/)
+* [Java 12](java-12/) (Mar, 2019)
   * Switch expression (preview)
   * Compact Number Format
   * Collectors improvements
   * CompletableFuture improvements
   * CDS enable by default
   * New GC and improvements
 
-* [Java 11](java-11/)
+* [Java 11](java-11/) (Sep, 2018)
   * Removal of Java EE Modules, JavaFX and deprecated API
   * Http Client (incubator)
   * var in lambda expressions
   * API improvements
   * Null I/O
 
-* [Java 10](java-10/) (March, 2018)
+* [Java 10](java-10/) (Mar, 2018)
   * Process API improvements
   * Collections improvements
   * Application Class-Data Sharing
   * `var` keyword to declare variables
 
-* [Java 9](java-9/)
+* [Java 9](java-9/) (Sep, 2017)
   * Milling Project Coin
   * Process API
   * Platform Logging API and Service
@@ -90,7 +90,7 @@ A project to explore more about the new features of Java 8, 9, ...
   * JShell
   * much more (see JEPs)
 
-* [Java 8](java-8/)
+* [Java 8](java-8/) (Marc, 2014)
   * API
   * Stream API
   * Project Lambda
@@ -102,4 +102,4 @@ A project to explore more about the new features of Java 8, 9, ...
 * [Inside.java - Sip of Java](https://inside.java/2021/10/21/sip24/)
 * [Considerations Bumping Java EE](https://vorozco.com/blog/2020/2020-08-21-considerations-bumping-javaee.html)
 * [The Role of Preview Features in Java and Beyond](https://blogs.oracle.com/javamagazine/the-role-of-previews-in-java-14-java-15-java-16-and-beyond)
-* [Place to get early releases from Oracle's JDK](https://jdk.java.net/)
+* [Place to get early releases from Oracle's JDK](https://jdk.java.net/)

java-18/README.md

@@ -6,6 +6,16 @@ To run each example use: `java --enable-preview --source 18 <FileName.java>`
 
 ### Language
 
+* chartset UTF-8 will be default for all O.S.
+  * to see which is default: `java -XshowSettings:properties -version 2>&1 | grep file.encoding`
+  * we can change the chartset with property: `-Dfile.encoding=UTF-8`
+  * affected classes:
+    * Stream Reader and Writer
+    * File Reader and Writer
+    * `Formatter` and `Scanner`
+    * `URLEncoder` and `URLDecoder`
+  * the `System.out` and `System.err` will use the same charset from the terminal
+      * we can see with: `Console.charset()`
 * Pattern matching for `switch`
   * Minor improvements from JDK 17:
     * refined to use dominance checking that will force constant case label to appear before a guarded pattern of the same type;

java-18/SimpleWebServer.java

@@ -0,0 +1,56 @@
+import com.sun.net.httpserver.*;
+import java.net.*;
+import java.io.*;
+import java.nio.file.*;
+import java.util.function.Predicate;
+
+/**
+ * To run from the terminal we can use the utility command-line tool:
+ * `jwebserver -b 0.0.0.0 -p 8080`
+ *
+ * The API only supports GET and HEAD requests, but we can added manual support with `HttpHandlers.handleOrElse`.
+ *
+ * Doc: https://download.java.net/java/early_access/jdk18/docs/api/jdk.httpserver/com/sun/net/httpserver/SimpleFileServer.html
+ */
+public class SimpleWebServer {
+	private static final String SERVER_DIR = System.getProperty("user.dir");
+
+	public static void main(String[] args) {
+		var server = SimpleFileServer.createFileServer(
+			new InetSocketAddress(8080),
+			Path.of(SERVER_DIR),
+			SimpleFileServer.OutputLevel.VERBOSE
+		);
+
+		var defaultHandler = HttpHandlers.of(404, new Headers(), "Not found");
+
+		Predicate<Request> IS_POST = req -> "POST".equals(req.getRequestMethod());
+
+		var postHandler = HttpHandlers.handleOrElse(
+			IS_POST,
+			(exchange) -> {
+				System.out.println("Handling POST request");
+
+				System.out.println("Headers:");
+				exchange.getRequestHeaders().forEach((k, v) -> System.out.printf("\t%s: %s\n", k, v));
+
+				InputStream requestBody = exchange.getRequestBody();
+				try (var reader = new BufferedReader(new InputStreamReader(requestBody))) {
+					System.out.println("\nBody:");
+					reader.lines().forEach(line -> System.out.printf("\t%s", line));
+				} catch (RuntimeException | IOException ex) {
+					System.err.println("Error reading request body: " + ex.getMessage());
+				}
+
+				var responseBody = "POST handled successfully".getBytes();
+				exchange.sendResponseHeaders(200, responseBody.length);
+				exchange.getResponseBody().write(responseBody);
+			},
+			defaultHandler
+		);
+		server.createContext("/post", postHandler);
+
+		server.start();
+		System.out.println("Server started at " + server.getAddress());
+	}
+}

java-18/SwitchWithPatternMatchingSecondPreview.java

@@ -13,21 +13,26 @@ public static void main(String[] args) {
 		System.out.println(stringify(-42));
 		System.out.println(stringify("Some text"));
 		System.out.println(stringify(""));
+		System.out.println(stringify(null));
 	}
 
 	static String stringify(Object value) {
 		return switch (value) {
 			// the constant must be before the guarded pattern (otherwise it will never hit)
-			case 42 -> "42 is the answer";
+			case Integer i && i == 42 -> "42 is the answer";
+			case Integer i && i > 0 -> "positive number";
 			case Integer i && i < 0 -> "negative number";
 			// this must be after because it will match all integers
-			case Integer i -> "some number";
+			case Integer i -> "should be 0";
 
 			case String s && s.isEmpty() -> "empty string";
 			case String s && s.length() > 50 -> "long string";
 			// this must be after because it will match all strings
 			case String s -> "non-empty string";
+			// same here
+			case CharSequence cs -> "any other CharSequence";
 
+			case null -> "null =s";
 			default -> "unhandled type";
 		};
 	}

java-18/index.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+	<meta charset="UTF-8">
+	<meta http-equiv="X-UA-Compatible" content="IE=edge">
+	<meta name="viewport" content="width=device-width, initial-scale=1.0">
+	<title>Simple Web Server</title>
+</head>
+<body>
+	Hello world from Simple Web Server!
+</body>
+</html>