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API Updates in Java SE 11 (18.9)

Mohamed Sanaulla

Java SE 11, which is also named as 18.9 (based on the new naming scheme which uses the year and month of release), is slated to be GA during the last week of September. The new approach for releasing new JDK version frequently is allowing the language creators to introduce new features, API updates more quickly to the developer community.

Often API updates go unnoticed and are buried under some major changes. So I thought of enumerating some of the API changes that would be in Java 11 which were not present in Java 10.

I am using the jdk-11-ea+16 build downloaded from here

Character.toString(int)

This method returns the string representation for the given Unicode code point as shown below:

jshell> Character.toString(100)
$10 ==> "d"
jshell> Character.toString(66)
$7 ==> "B"

CharacterSequence.compare(java.lang.CharSequence, java.lang.CharSequence)

This compares two character sequence lexicographically and return negative, zero or positive if first character sequence is lexicographically less than or equal to or greater than the second respectively.

Lexicographically means dictionary order or alphabetical order.

jshell> CharSequence.compare("girl", "boy")
$12 ==> 5

jshell> CharSequence.compare("girl", "girl")
$13 ==> 0

jshell> CharSequence.compare("hello", "world")
$14 ==> -15

New APIs in java.lang.String

repeat(int)

jshell> "**".repeat(5)
$15 ==> "**********"

jshell> "**".repeat(-7)
|  Exception java.lang.IllegalArgumentException: count is negative: -7
|        at String.repeat (String.java:3147)
|        at (#16:1)

jshell> "**".repeat(0)
$17 ==> ""

jshell> "**".repeat(1)
$18 ==> "**"

isBlank()

jshell> String msg = "hello"
msg ==> "hello"

jshell> msg.isBlank()
$22 ==> false

jshell> String msg = ""
msg ==> ""

jshell> msg.isBlank()
$24 ==> true

jshell> String msg = " "
msg ==> " "

jshell> msg.isBlank()
$26 ==> true

strip(), stripTrailing(), stripLeading()

jshell> " hello world ".strip()
$29 ==> "hello world"

jshell> "hello world    ".strip()
$30 ==> "hello world"

jshell> "hello world    ".stripTrailing()
$31 ==> "hello world"

jshell> "        hello world    ".stripLeading()
$32 ==> "hello world    "

jshell> "    ".strip()
$33 ==> ""

lines()

jshell> String content =  "this is a multiline content\nMostly obtained from some file\rwhich we will break into lines\r\nusing the new api"
content ==> "this is a multiline content\nMostly obtained fro ... ines\r\nusing the new api"

jshell> content.lines()
$36 ==> java.util.stream.ReferencePipeline$Head@5ec0a365

jshell> content.lines().forEach(System.out::println)
this is a multiline content
Mostly obtained from some file
which we will break into lines
using the new api

java.nio.file.Path.of()

Prior to this release, there were no factory methods in java.nio.file.Path, while there was one method in java.nio.file.Paths. This release introduces a factory method in java.nio.file.Path of which there are two variants:
1. Takes String location to the resource
2. Takes URI location to the resource
Both of them are shown below:

jshell> Path uriPath = Path.of(new URI("file:///C:/Program%20Files/Java/jdk-11/release"))
uriPath ==> C:\Program Files\Java\jdk-11\release

jshell> Files.readAllLines(uriPath).forEach(System.out::println)

jshell> Path filePath = Path.of("..", "release")
filePath ==> ..\release

jshell> Files.readAllLines(filePath).forEach(System.out::println)

Pattern.asMatchPredicate()

This API returns a java.util.function.Predicate which can be used to test if a given string matches the pattern compiled using the java.util.regex.Pattern

jshell> Pattern somePattern =  Pattern.compile("\\w+@\\w+[.]com")
somePattern ==> \w+@\w+[.]com

jshell> Predicate<String> somePredicate = somePattern.asMatchPredicate()
somePredicate ==> java.util.regex.Pattern$$Lambda$26/0x00000008000d0840@34c4973

jshell> somePredicate.test("sana@gmail.net")
$55 ==> false

jshell> somePredicate.test("sana@gmail.com")
$56 ==> true

jshell> somePredicate.test("sana#@gmail.com")
$57 ==> false

The Java EE related APIs namely Corba, JAXB, JAX WS (Web Services) are being removed. The HTTP Client library which was in the incubator until Java 10 is being moved out of incubator into its own module java.net.http. I will son write some posts on the new HTTP Client

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