Java 8-12

Let's talk about new features in Java 8 -12, let' start!

Java 8

• Functional Interfaces & Lambda Expressions

• Stream API ( this comes with filter, map, flatmap, reduce, collect methods) for Bulk operations

See here for details on these two.

• forEach() for Iterable implemented Collections

• Default & static Methods inside Interface

• Time API
• Files API 
• Files.lines(path)
• Files.list(dir)
• BufferedReader.stream()
• Files.find()

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Java 9

• Modularity

Java API itself has been modularised and you can now modularise your application too. This is good from Containerisation perspective etc. , thin modules with defined exposure/boundary.

Why Modularity:

• Have only what you need, dont need whole JDK

 Use jlink Module 

For example, use following in your java class :

module jlinkModule {

    requires java.logging;

}

This will have a custom JDK having logging

and default ones ( like Object, class & String)

• Less Space
• Public is also not visible across Modules, even using reflection so better encapsulation
• Better performance
• Better Security & maintainability

         Module Types

         Application modules, Automated,                       unnamed & platform modules.

• Jshell

• Use Jlink

• Search facility in JavaDoc :) 

• Collection Factory Methods

• Stream API Improvements

dropWhile, takeWhile, ofNullable

• Private Interface methods

• Multi-release JARs

Here you can have 2 version of a class, one say for JDK 9 and another for previous versions.

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Java 10

• Parallel Full GC for G1

• var Type & Local variable Type inference

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Java 11

• Local parameter type inference for Lambda Variables using var (Also allowed @NonNull etc)

• Repeat Method in String to copy

• Path.of(path)

• Files.readString & Files.writeString()

• String.lines

• Optional.isEmpty

• Strip, StripLeading, StripTrailing

• Improved toArray

Employee[] employeeArray = employeeList.toArray(Employee[]::new)

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Java 12

• Improved Switch with expression supported

switch(DAY){

case SUNDAY  : return 0; break;

case MONDAY  : return 1; break;

---

Now it is :

int day = Switch(DAY) {

case SUNDAY -> 0;

case MONDAY-> 1; 

}

• Teeing Collector

To have a Average value of array, typical code could be :

Integer[] array = {6,2,3,4,5,1};

Double average = Arrays.stream(array).map(x->(Double.valueOf(x))).reduce

(0d,(x,y)-> (x + (y/array.length)),(a,b)->a +b);

System.out.println(average);

With Teeing, it is :

Double result = Stream.of(1,2,3,4,5,6).

collect(teeing(

    summingDouble(x -> x),

    counting(),

    (sum, total) -> sum / total);

System.out.println(result); // 3.5

• Improved low pause Shenandoah GC algorithm ( pause time independent of Heap Size)
• Improved G1 (Return unused memory immediately)