String

https://stackoverflow.com/questions/51266582/difference-between-string-trim-and-strip-methods-in-java-11

  • strip
  • stripLeading
  • stripTrailing
jshell> var s="     text    "
s ==> "     text    "
|  modified variable s : String
|    update overwrote variable s : String

jshell> s.strip()
$6 ==> "text"


jshell> s.stripLeading()
$7 ==> "text    "
  • isEmpty
jshell> s.isEmpty()
$9 ==> false

jshell> "".isEmpty()
$10 ==> true
  • lines
jshell> "aaa\nbbbb\n\ncccc".lines().collect(Collectors.toList())
$12 ==> [aaa, bbbb, , cccc]
  • repeat
jshell> "<".repeat(3) + "text" + ">".repeat(3)
$13 ==> "<<<text>>>"

Files

  • Read/Write to file
jshell> var myFile=Path.of("tests.txt")
myFile ==> tests.txt

jshell> Files.writeString(myFile,"aaa\nbbb\nccc")
$16 ==> tests.txt

jshell> Files.readString(myFile)
$17 ==> "aaa\nbbb\nccc"

jshell> Files.isSameFile(myFile,myFile)
$18 ==> true

Regex and Streams

jshell> var p =Pattern.compile("^error.*$").asMatchPredicate()
jshell> List.of("error: errorA","error:errorB","debug:DebugA","error:ErrorC").stream().filter(p).toArray()
$35 ==> Object[3] { "error: errorA", "error:errorB", "error:ErrorC" }

var in lambdas

public interface Test{
   ...> public void testMethod(String s);
   ...> }


jshell> Test t= s -> System.out.println(s)
t ==> $Lambda$31/0x00000008000bd840@4b553d26

jshell> t.testMethod("aaa")
aaa

jshell> Test t= (var s) -> System.out.println(s)
t ==> $Lambda$31/0x00000008000bd840@4b553d26

jshell> t.testMethod("bbb")
bbb

Predicate.not

lines.stream().filter(not(String::isBlank))

MatchPredicate

jshell> var aaPredicate=Pattern.compile("aaa").asMatchPredicate()
aaPredicate ==> java.util.regex.Pattern$$Lambda$220/0x00000008001f4840@639c2c1d

jshell> aaPredicate.test("abc")
$46 ==> false

jshell> aaPredicate.test("aaa")
$47 ==> true

Nested Classes

http://openjdk.java.net/jeps/181

Why it is important :

In

  • In generic specialization each specialized type could be created as a nestmate of the generic type.
  • A safe and supported replacement for the Unsafe.defineAnonymousClass() API could create the new class as a nestmate of an existing class.
  • The concept of "sealed classes" could be effected by only allowing subclasses that are nestmates.
  • Truly private nested types could be effected (presently private nested types are defined with package-access).

JEPS

public class HelloSingleFile {

    public static void main(String[] args) {
            System.out.println("Hello From Single File");
    }
}

>java HelloSingleFile.java 
Hello From Single File

 #!/usr/bin/java --source 11
            public class HelloWorld {

var request = HttpRequest.newBuilder()
    .uri(URI.create("https://winterbe.com"))
    .GET()
    .build();
var client = HttpClient.newHttpClient();
var response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());

jshell> var uri= URI.create("http://www.pogodynka.pl")
uri ==> http://www.pogodynka.pl

jshell> var request=HttpRequest.newBuilder().uri(uri).GET().build()
request ==> http://www.pogodynka.pl GET

jshell> var client = HttpClient.newHttpClient()

var response = client.send(request, HttpResponse.BodyHandlers.ofString())
jshell> response.body()

Async

var response = client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
response.thenApply(HttpResponse::body).thenAccept(System.out::println)

var stringPublisher=HttpRequest.BodyPublishers.ofString("Hi There!")
stringPublisher ==> jdk.internal.net.http.RequestPublishers$StringPublisher@3023df74

jshell> var req=HttpRequest.newBuilder().uri(postmanURI).
   ...> header("Content-type","text/plain").
   ...> POST(stringPublisher).
   ...> build()
req ==> https://postman-echo.com/post POST
jshell> HttpResponse.BodyHandler
BodyHandler    BodyHandlers   

jshell> var stringHandler=HttpResponse.BodyHandlers.ofString()
stringHandler ==> java.net.http.HttpResponse$BodyHandlers$$Lambda$78/0x0000000800168840@2a65fe7c


jshell> var r=client.send(req,stringHandler)
r ==> (POST https://postman-echo.com/post) 200

jshell> r.statusCode()
$44 ==> 200

  • EMOJI

jshell> var sb=new StringBuilder()
sb ==> 

jshell> Stream.iterate(127767,i->i+1).map(Character::toChars).limit(100).forEach(sb::append)

jshell> sb
sb ==> 🌗🌘🌙🌚🌛🌜🌝🌞🌟🌠🌡🌢🌣🌤🌥🌦🌧🌨🌩🌪🌫🌬🌭🌮🌯🌰🌱🌲🌳🌴🌵🌶🌷🌸🌹🌺🌻🌼🌽🌾🌿🍀🍁🍂🍃🍄🍅🍆🍇🍈🍉🍊🍋🍌🍍🍎🍏🍐🍑🍒🍓🍔🍕🍖🍗🍘🍙🍚🍛🍜🍝🍞🍟🍠🍡🍢🍣🍤🍥🍦🍧🍨🍩🍪🍫🍬🍭🍮🍯🍰🍱🍲🍳🍴🍵🍶🍷🍸🍹🍺

API

GC for BigData

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