More Java 11 examples

Author: winterbe

src/com/winterbe/java11/HttpClientExamples.java

@@ -19,39 +19,40 @@ public static void main(String[] args) throws IOException, InterruptedException
     }
 
     private static void syncRequest() throws IOException, InterruptedException {
-        var client = HttpClient.newHttpClient();
         var request = HttpRequest.newBuilder()
                 .uri(URI.create("https://winterbe.com"))
                 .build();
+        var client = HttpClient.newHttpClient();
         HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
         System.out.println(response.body());
     }
 
     private static void asyncRequest() {
-        var client = HttpClient.newHttpClient();
         var request = HttpRequest.newBuilder()
                 .uri(URI.create("https://winterbe.com"))
                 .build();
+        var client = HttpClient.newHttpClient();
         client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
                 .thenApply(HttpResponse::body)
                 .thenAccept(System.out::println);
     }
 
     private static void postData() throws IOException, InterruptedException {
-        var client = HttpClient.newHttpClient();
         var request = HttpRequest.newBuilder()
                 .uri(URI.create("https://postman-echo.com/post"))
                 .timeout(Duration.ofSeconds(30))
                 .version(HttpClient.Version.HTTP_2)
                 .header("Content-Type", "text/plain")
                 .POST(HttpRequest.BodyPublishers.ofString("Hi there!"))
                 .build();
+        var client = HttpClient.newHttpClient();
         var response = client.send(request, HttpResponse.BodyHandlers.ofString());
         System.out.println(response.statusCode());      // 200
     }
 
     private static void basicAuth() throws IOException, InterruptedException {
         var client = HttpClient.newHttpClient();
+
         var request1 = HttpRequest.newBuilder()
                 .uri(URI.create("https://postman-echo.com/basic-auth"))
                 .build();

src/com/winterbe/java11/Misc.java

@@ -0,0 +1,69 @@
+package com.winterbe.java11;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class Misc {
+
+    @Deprecated(forRemoval = true)
+    String foo;
+
+    public static void main(String[] args) throws IOException {
+        collections();
+        strings();
+        optionals();
+        inputStreams();
+        streams();
+    }
+
+    private static void streams() {
+        System.out.println(Stream.ofNullable(null).count());   // 0
+        System.out.println(Stream.of(1, 2, 3, 2, 1)
+                .dropWhile(n -> n < 3)
+                .collect(Collectors.toList()));     // [3, 2, 1]
+        System.out.println(Stream.of(1, 2, 3, 2, 1)
+                .takeWhile(n -> n < 3)
+                .collect(Collectors.toList()));     // [1, 2]
+    }
+
+    private static void inputStreams() throws IOException {
+        var classLoader = ClassLoader.getSystemClassLoader();
+        var inputStream = classLoader.getResourceAsStream("com/winterbe/java11/dummy.txt");
+        var tempFile = File.createTempFile("dummy-copy", "txt");
+        try (var outputStream = new FileOutputStream(tempFile)) {
+            inputStream.transferTo(outputStream);
+        }
+        System.out.println(tempFile.length());
+    }
+
+    private static void optionals() {
+        System.out.println(Optional.of("foo").orElseThrow());   // foo
+        System.out.println(Optional.ofNullable(null).or(() -> Optional.of("bar")).get());   // bar
+        System.out.println(Optional.of("foo").stream().count());    // 1
+    }
+
+    private static void strings() {
+        System.out.println(" ".isBlank());
+        System.out.println(" Foo Bar ".strip());    // "Foo Bar"
+        System.out.println(" Foo Bar ".stripTrailing());    // " Foo Bar"
+        System.out.println(" Foo Bar ".stripLeading());    // "Foo Bar "
+        System.out.println("Java".repeat(3));    // "JavaJavaJava"
+        System.out.println("A\nB\nC".lines().count());  // 3
+    }
+
+    private static void collections() {
+        var list = List.of("A", "B", "C");
+        var copy = List.copyOf(list);
+        System.out.println(list == copy);   // true
+
+        var map = Map.of("A", 1, "B", 2);
+        System.out.println(map);
+    }
+
+}

src/com/winterbe/java11/dummy.txt

@@ -0,0 +1 @@
+Foobar