Java Versions

Java 9

JShell

• The Java Shell tool (JShell) is an interactive tool for learning the Java programming language and prototyping Java code.
• JShell is a Read-Evaluate-Print Loop (REPL), which evaluates declarations, statements, and expressions as they are entered and immediately shows the results.
• The tool is run from the command line.
• Using JShell, you can enter program elements one at a time, immediately see the result, and make adjustments as needed.
• You can use Java to write scripts!

Modules

(Java 9 Platform Module System - JPMS)

• Modularity adds a higher level of aggregation above packages.

• The key new language element is the module:

  • a uniquely named, reusable group of related packages, as well as resources (such as images and XML files) and a module descriptor specifying.

Private interface Methods

public interface MyInterface {

    void normalInterfaceMethod();

    default void interfaceMethodWithDefault() {  init(); }

    default void anotherDefaultMethod() { init(); }

    // This method is not part of the public API exposed by MyInterface
    private void init() { System.out.println("Initializing"); }
    
    // This method is not part of the public API exposed by MyInterface
    private static void doSomething() { System.out.println("Doing Something!"); }
}

Collection Factory Methods

Set<Integer> ints = Set.of(1, 2, 3);
List<String> strings = List.of("first", "second");

More Resources

• 9 new features in Java 9
• Java 9 Features with Examples
• Java Platform, Standard Edition Java Shell User’s Guide
• Understanding Java 9 Modules
• A Guide to Java 9 Modularity

Java 10

Local Variable Type Inference

String message1 = "Good bye, Java 9";

var message2 = "Hello, Java 10";

Map<Integer, String> map = new HashMap<>();

var idToNameMap = new HashMap<Integer, String>();

• Note that this feature is available only for local variables with the initializer.

  • It cannot be used for member variables, method parameters, return types, etc.

  • The initializer is required as without which compiler won’t be able to infer the type.

It is not always a good idea to use a var.

var result = obj.prcoess();
    
var x = emp.getProjects.stream()
    .findFirst()
    .map(String::length)
    .orElse(0);

Container Awareness

• JVMs are now aware of being run in a Docker container and will extract container-specific configuration instead of querying the operating system itself.

  • This applies to data like the number of CPUs and total memory that have been allocated to the container.

• This support is only available for Linux-based platforms

copyOf()

(Create Unmodifiable Collections)

• java.util.List, java.util.Map and java.util.Set each got a new static method copyOf(#collection#).
• It returns the unmodifiable copy of the given Collection.

List<Integer> copyList = List.copyOf(someIntList);

• Any attempt to modify such a collection would result in java.lang.UnsupportedOperationException runtime exception.

toUnmodifiable###()

• java.util.stream.Collectors get additional methods to collect a Stream into an unmodifiable List, Map or Set.

List<Integer> evenList = someIntList.stream()
    .filter(i -> i % 2 == 0)
    .collect(Collectors.toUnmodifiableList());

• Any attempt to modify such a collection would result in java.lang.UnsupportedOperationException runtime exception.

Time-Based Release Versioning

• A new Java release every six months starting from this version (Java 10 / 18.3).
  • These are called feature releases and are expected to contain at least one significant feature.
  • Support for the feature release will last only for six months, i.e., until next feature release.

• Long-term support release will be marked as LTS.
  • Support for such release will be for three years.
  • Java 11 (18.9) will be an LTS release.

More Resources

• New Features in Java 10
• Java 10 Local Variable Type-Inference

Java 11

The Current LTS Version

Oracle vs. Open JDK

• Java 10 was the last free Oracle JDK release that we could use commercially without a license.
• Starting with Java 11, there’s no free long-term support (LTS) from Oracle.
• Open JDK releases are still free and open-source.

New String Methods

• isBlank: Empty Strings and Strings with only white spaces are treated as blank.

System.out.println(" ".isBlank());      // true
System.out.println("Noor".isBlank());   // false
System.out.println("".isBlank());       // true

• lines: Returns a stream of strings, which is a collection of all substrings split by lines.
  • Can be very useful when reading from files.

String str = "First\nSecond\nThird"; 
System.out.println(str);
System.out.println("---");
System.out.println(str.lines().collect(Collectors.toList()));

This will result in the following output:

First
Second
Third
---
[First, Second, Third]

• strip: Removes the white space from both, beginning, and the end of string.
• stripLeading: Removes the white space from the beginning of string.
• stripTrailing: Removes the white space from the end of string.

String str = "  Noor  ";
System.out.println("|" + str                  + "|"); // |  Noor  |
System.out.println("|" + str.strip()          + "|"); // |Noor|
System.out.println("|" + str.stripLeading()   + "|"); // |Noor  |
System.out.println("|" + str.stripTrailing()  + "|"); // |  Noor|

• repeat: Returns a string whose value is the concatenation of this string repeated count times.

System.out.println("=".repeat(10));   // ==========

New File Methods

• We can use the new readString and writeString static methods from the Files class.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

public class StringMethods {
    public static void main(String[] args) throws IOException {
        Path filePath = Files.createFile(Path.of("file.txt"));
        
        // writeString: will wtite a string to the file
        Files.writeString(filePath, "Sample text");
        
        // readString: will read the file as a string
        String fileContent = Files.readString(filePath);
        
        System.out.println(fileContent);  // Sample text
    }
}

The not Predicate Method

import java.util.List;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class StringMethods {
    public static void main(String[] args) {
        List<String> sampleList = List.of("Hello", "\n \n", "World", " ", "");

        // Java 10 and before
        List<String> notEmptyStrings10 = sampleList.stream()
                .filter(s -> !s.isBlank())
                .collect(Collectors.toList());
        System.out.println(notEmptyStrings10);  // [Hello, World]

        // Java 11
        List<String> notEmptyStrings11 = sampleList.stream()
                .filter(Predicate.not(String::isBlank))
                .collect(Collectors.toList());
        System.out.println(notEmptyStrings11);  // [Hello, World]
    }
}

More Resources

• New Features in Java 11
• Java 11 Features
• What is new in Java 11

Java 12

New String Methods

• indent: Adjusts the indentation of each line of this string based on the value of n.

String text = "Hello World!\nThis is Noor.";
System.out.println(text.indent(4));

    Hello World!
    This is Noor.

There are some other new methods, like transform.

File::mismatch Method

• Finds and returns the position of the first mismatched byte in the content of two files, or -1L if there is no mismatch.
• The position will be in the inclusive range of 0L up to the size (in bytes) of the smaller file.

More Resources

• New Features in Java 12
• Java 12 Features
• Java 12: New Features and Enhancements Developers Should Know

Java 13

Not a lot of finalized new features are introduced in Java 13.

More Resources

• New Features in Java 13
• Java 13 Features
• Java 13 – a deep dive into the JDK’s new features