Java 11 is the next LTS(Long Term Support) release after Java 8.

New Java 11 features

Some of the main features introduced in Java 11 are following:

New Licensing Model

Starting Java 11 Oracle JDK Licensing has changed, you can use it for personal projects and learning for no cost. If you want to use Oracle JDK for Java 11 commercially, you will have to buy a commercial license from Oracle.

This is true for new updates to Java 8 as well. You can continue using Java 8 versions before April 16, 2019 as you wish. But, if you want to get any newer updates you will have to buy a commercial license.

This doesn’t mean you can’t get Java for free now. Lots of companies, including Oracle, contribute to open source project called OpenJDK. OpenJDK is free alternative to Oracle JDK.

You can get OpenJDK from here

JEP 330: Run Java with a Single Command and SheBang

Javac not Needed Anymore

These days not many people use command line to run and compile a Java file but still, some times it can be handy to run java program from a command line tool.

Before Java 11 it was a 2 step process.

  • first compile the file using javac command. E.g javac MyJavaClass.java.
  • And then, run it java MyJavaClass

Starting Java 11 you can compile and run a program with one command. Eg. java MyOtherClass.java, no need to use javac anymore. This one command will both compile and run your class.

Use the SheBang in scripts

Single file java program can be run using Shebang.

Shebang is the first line of a shell script, which specifies the binary to use for the script. Generally its used to define which shell will be used eg. bash, sh etc.

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

    public static void main(String[] args) {

        System.out.println("Hello World!,");

    }
}

Now you can run this program like you would run a script.

./HelloWorld.sh

JEP 323: Local Variable Syntax for Lambda

Java 10 introduced var keyword for automatic type inference. In Java 11 Lambda’s also support var keyword in lambda parameters.

Consider the following Lambda expression

Function<String,String> convertCase = (input) -> input.toUpperCase();

This lambda takes a String and converts it too upper case. Note that Function is predefined functional interface in java.util.function package

String convertedString = convertCase.apply("caps are considered shouting in chat");
// convertedString is set to CAPS ARE CONSIDERED SHOUTING IN CHAT

In Java 11, we could use var keyword.

Function<String,String> convertCase = (var input) -> input.toUpperCase();

This isn’t any better from the previous declaration of convertCase. But using var allows you to use annotations, which is an improvement

Function<String,String> convertCase = (@NotNull var input) -> input.toUpperCase();

NotNull is not part of standard java, although there are many common implementation of NotNull in various libraries.

JEP 320 Remove the Java EE and CORBA Modules

Following packages were removed from Java 11.

  • java.xml.ws (JAX-WS, plus the related technologies SAAJ and Web Services Metadata)
  • java.xml.bind (JAXB)
  • java.activation (JAF)
  • java.xml.ws.annotation (Common Annotations)
  • java.corba (CORBA)
  • java.transaction (JTA)
  • java.se.ee (Aggregator module for the six modules above)
  • jdk.xml.ws (Tools for JAX-WS)
  • jdk.xml.bind (Tools for JAXB)

JEP 328: Flight Recorder

Flight Recorder is a profiling tool to diagnose a running Java application. It has existed for many years and was previously a commercial feature of the Oracle JDK. Starting Java 11 it is open source.

Api changes

New String Methods

  • String repeat(int count)

    As the name suggests it repeats the string its invoked on count number of times.

    String str = "A".repeat(5)
// str contains "AAAAA"

    If string is empty or count is 0 then empty string is returned.

  • boolean isBlank()

    Returns true if string is empty or only contains whitespace.

    boolean blank = "".isBlank();// true
blank = " ".isBlank(); // true
blank = " v ".isBlank(); // false

  • Stream<String> lines()

    Returns a stream of lines extracted from the string it is called on. Lines in strings are separated by line terminators ie. \n, \r, \r\n.

    "my \n name \n is \n vikram".lines().forEach(System.out::println)
// prints following:
// my
// name
// is
// vikram

    above is equivalent to having a list of string, converting it to a Stream and then apply string operations, in this case foreach

    List<String> list = List.of("my ", "name ", "is ", "vikram");
list.stream().forEach(System.out::println);

New Collection.toArray() function

New function has been added to Collection interface.

<T> T[] toArray​(IntFunction<T[]> generator)

IntFunction is an functional interface which allocates the returned array.

Lets convert a List of String to an array

List<String> list = List.of("one","two", "three");
String[] array = list.toArray(String[]::new);
// array ==> String[3] { "one", "two", "three" }

Files.readString() and Files.writeString()

  • Files.readString: reads a file to a String. This method ensures file is properly closed when reading is finished.

    It has 2 overloads

    • public static String readString​(Path path, Charset cs) throws IOException

      This method converts all the bytes read into the provided charset.

    • public static String readString​(Path path) throws IOException

      This is equivalent to calling first method with charset UTF 8.

  • Files.writeString: As you might have guessed, this function can be used to write a String to a file.

    It also has 2 overloads.

    • public static Path writeString​(Path path, CharSequence csq, Charset cs, OpenOption... options) throws IOException Writes a the Character sequence specified at the path provided,in the given charset. Uses options to decide how the file should be opened.
    • public static Path writeString​(Path path, CharSequence csq, OpenOption... options) throws IOException In this overload version charsequence is UTF 8.

Lets see a code example

jshell> String secret = "Secret to success is hard work!"
secret ==> "Secret to success is hard work!"
jshell> Path path = Files.writeString(Files.createTempFile("secret", ".txt"),secret);
path ==> C:\Users\vikramsingh\AppData\Local\Temp\secret3433019555033269602.txt

jshell> String s = Files.readString(path);
s ==> "Secret to success is hard work"

Optional.isEmpty method

Optional class already contains a method isPresent which is true when optional object contains a value.

isEmpty is opposite of isPresent i.e its true when optional object doesn’t contains a value.

Idea behind is to remove negative conditions when checking value is not isPresent i.e instead of using !optional.isPresent now we can use use optional.isEmpty

String name=null;
Optional<String> strOptional = Optional.ofNullable(name);

System.out.println(strOptional.isPresent())  // false
System.out.println(!strOptional.isPresent()) // true
System.out.println(strOptional.isEmpty());   // true

JEP 321: HTTP Client (Standard)

New Http Client was added in Java 9 as an early preview for feedback by users. Starting Java 11 this new Http Client standardized and can be used in commercial applications. Its available in package java.net.http package.

In Java 9 and 10, it was available at jdk.incubator.http, so if you were already trying the incubator version just update the import.

This client introduces support to HTTP/2 and allows non-blocking request and response semantics through CompletableFutures.

JEP 327: Unicode 10

Java 11 supports version 10 of Unicode Standard, which means more special symbols/emoji’s available in Java.

JEP 332: Transport Layer Security (TLS) 1.3

Java 11 supports TLS 1.3, however not all TLS 1.3 features are supported.

JEP 335: Deprecate the Nashorn JavaScript Engine

Nashorn JavaScript script engine and APIs and the jjs tool, introduced in Java 8, have been deprecated and would be removed in a future version of Java.

JEP 336: Deprecate the Pack200 Tools and API

The pack200 and unpack200 tools, and the Pack200 API in java.util.jar package have been deprecated and it will probably remove in the future release.