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@mcupak
Created Oct 6, 2019
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Export of my JShell session from the The good, the bad, and the ugly of Java API design talk at Detroit Java User Group 2019.
List<Integer> list = new ArrayList<Integer>()
list.add(1)
list.add(2)
list.add(3)
list = Collections.unmodifiableList(list)
Collections.unmodifiableList(Arrays.asList(1,2,3))
Collections.unmodifiableList(Stream.of(1,2,3).collect(toList()))
Collections.unmodifiableList(new ArrayList<Integer>() {{ add(1); add(2); add(3); }})
/env -class-path guava-27.1-jre.jar
import com.google.common.collect.ImmutableList
ImmutableList.of(1,2,3)
List<Integer> list2 = new ArrayList<Integer>(list)
list2.add(4)
List<Integer> list2 = Collections.unmodifiableList(new ArrayList<Integer>(list))
List<Integer> list = List.of(1,2,3)
list.add(4)
list.getClass()
Map.ofEntries(entry(1, "hello"))
List<Integer> list2 = List.copyOf(list)
list2.add(4)
Set.copyOf(list)
list.stream().collect(toUnmodifiableSet())
list.toArray(Integer[]::new)
StackTraceElement[] st = new Throwable().getStackTrace()
Thread.currentThread().getStackTrace()
StackWalker.getInstance().walk(s -> s.collect(toList()))
StackWalker.getInstance().walk(s -> s.limit(3).collect(toList()))
StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE).walk(s -> s.map(f -> f.getDeclaringClass()).collect(toList()))
new ProcessBuilder().command("jps").start()
/env -class-path commons-exec-1.3.jar
import org.apache.commons.exec.*
new DefaultExecutor().execute(CommandLine.parse("jps"))
ProcessHandle.current().pid()
ProcessHandle.current().info()
ProcessHandle.current().info().commandLine()
ProcessHandle.allProcesses().map(p -> p.info().command()).collect(toList())
new ProcessBuilder().command("sleep", "3").start().toHandle().onExit().thenAccept(System.out::println)
ProcessBuilder jps = new ProcessBuilder().command("jps")
ProcessBuilder grep = new ProcessBuilder().command("grep", "JShell")
List<Process> pipeline = ProcessBuilder.startPipeline(List.of(jps, grep))
pipeline.get(1).getInputStream().transferTo(System.out)
HttpHandler handler = he -> {
String body = "hello djug";
he.sendResponseHeaders(200, body.length());
try (OutputStream os = he.getResponseBody()) {
os.write(body.getBytes());
}
}
/l handler
HttpServer hs = HttpServer.create(new InetSocketAddress(8000), 0)
hs.createContext("/hello", handler)
hs.start()
URI uri = URI.create("http://localhost:8000/hello")
HttpURLConnection c = (HttpURLConnection) uri.toURL().openConnection()
c.setRequestMethod("GET")
c.getResponseCode()
new BufferedReader(new InputStreamReader(c.getInputStream())).readLine()
HttpClient client = HttpClient.newHttpClient()
client.version()
HttpRequest request = HttpRequest.newBuilder().uri(uri).GET().build()
HttpResponse<String> response = client.send(request, BodyHandlers.ofString())
response.statusCode()
response.body()
CompletableFuture<HttpResponse<String>> response = client.sendAsync(request, BodyHandlers.ofString())
response.get().body()
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