Java 8 - Overview

JAVA 8 (aka jdk 1.8) is a major release of JAVA programming language development. Its initial version was released on 18 March 2014. With the Java 8 release, Java provided support for functional programming, new JavaScript engine, new APIs for date time manipulation, new streaming API, etc.

Java 8 - Environment Setup

Try it Option Online

We have set up the Java Programming environment online, so that you can compile and execute all the available examples online. It gives you confidence in what you are reading and enables you to verify the programs with different options.

Java 8 - Lambda Expressions

Lambda expressions are introduced in Java 8 and are touted to be the biggest feature of Java 8. Lambda expression facilitates functional programming, and simplifies the development a lot.

Java 8 - Method References

Method references help to point to methods by their names. A method reference is described using :: (double colon) symbol. A method reference can be used to point the following types of methods −

Java 8 - Functional Interfaces

Functional interfaces have a single functionality to exhibit. For example, a Comparable interface with a single method ‘compareTo’ is used for comparison purpose. Java 8 has defined a lot of functional interfaces to be used extensively in lambda expressions. Following is the list of functional interfaces defined in java.util.Function package.

Java 8 - Default Methods

Java 8 introduces a new concept of default method implementation in interfaces. This capability is added for backward compatibility so that old interfaces can be used to leverage the lambda expression capability of Java 8.

Java 8 - Streams

Stream is a new abstract layer introduced in Java 8. Using stream, you can process data in a declarative way similar to SQL statements. For example, consider the following SQL statement −

SELECT max(salary), employee_id, employee_name FROM Employee

Java 8 - Optional Class

Optional is a container object which is used to contain not-null objects. Optional object is used to represent null with absent value. This class has various utility methods to facilitate code to handle values as ‘available’ or ‘not available’ instead of checking null values. It is introduced in Java 8 and is similar to what Optional is in Guava.

Class Declaration

Following is the declaration for java.util.Optional<T> class −

public final class Optional<T>
extends Object

Class Method

S. No.	Method & Description
1	static <T> Optional<T> empty() Returns an empty Optional instance.
2	boolean equals(Object obj) Indicates whether some other object is "equal to" this Optional.
3	Optional<T> filter(Predicate<? super <T> predicate) If a value is present and the value matches a given predicate, it returns an Optional describing the value, otherwise returns an empty Optional.
4	<U> Optional<U> flatMap(Function<? super T,Optional<U>> mapper) If a value is present, it applies the provided Optional-bearing mapping function to it, returns that result, otherwise returns an empty Optional.
5	T get() If a value is present in this Optional, returns the value, otherwise throws NoSuchElementException.
6	int hashCode() Returns the hash code value of the present value, if any, or 0 (zero) if no value is present.
7	void ifPresent(Consumer<? super T> consumer) If a value is present, it invokes the specified consumer with the value, otherwise does nothing.
8	boolean isPresent() Returns true if there is a value present, otherwise false.
9	<U>Optional<U> map(Function<? super T,? extends U> mapper) If a value is present, applies the provided mapping function to it, and if the result is non-null, returns an Optional describing the result.
10	static <T> Optional<T> of(T value) Returns an Optional with the specified present non-null value.
11	static <T> Optional<T> ofNullable(T value) Returns an Optional describing the specified value, if non-null, otherwise returns an empty Optional.
12	T orElse(T other) Returns the value if present, otherwise returns other.
13	T orElseGet(Supplier<? extends T> other) Returns the value if present, otherwise invokes other and returns the result of that invocation.
14	<X extends Throwable> T orElseThrow(Supplier<? extends X> exceptionSupplier) Returns the contained value, if present, otherwise throws an exception to be created by the provided supplier.
15	String toString() Returns a non-empty string representation of this Optional suitable for debugging.

Note − This class inherits methods from the java.lang.Object class.

Optional Example

To understand how Optional is used in practice, let us see the following example. Write the following program, execute and verify result to get more insight of it.

Java8Tester.java

import java.util.Optional;

public class Java8Tester {
   public static void main(String args[]){
   
      Java8Tester java8Tester = new Java8Tester();
      Integer value1 = null;
      Integer value2 = new Integer(10);
  
      //Optional.ofNullable - allows passed parameter to be null.
      Optional<Integer> a = Optional.ofNullable(value1);
  
      //Optional.of - throws NullPointerException if passed parameter is null
      Optional<Integer> b = Optional.of(value2);
      System.out.println(java8Tester.sum(a,b));
   }
 
   public Integer sum(Optional<Integer> a, Optional<Integer> b){
 
      //Optional.isPresent - checks the value is present or not
  
      System.out.println("First parameter is present: " + a.isPresent());
      System.out.println("Second parameter is present: " + b.isPresent());
  
      //Optional.orElse - returns the value if present otherwise returns
      //the default value passed.
      Integer value1 = a.orElse(new Integer(0));
  
      //Optional.get - gets the value, value should be present
      Integer value2 = b.get();
      return value1 + value2;
   }
}

Verify the Result

Compile the class using javac compiler as follows −

$javac Java8Tester.java

Now run the Java8Tester as follows −

$java Java8Tester

It should produce the following output −

First parameter is present: false
Second parameter is present: true
10

Java 8 - Nashorn JavaScript

With Java 8, Nashorn, a much improved javascript engine is introduced, to replace the existing Rhino. Nashorn provides 2 to 10 times better performance, as it directly compiles the code in memory and passes the bytecode to JVM. Nashorn uses invokedynamics feature, introduced in Java 7 to improve performance.

Java 8 - New Date/Time API

With Java 8, a new Date-Time API is introduced to cover the following drawbacks of old date-time API −

• Not thread safe − java.util.Date is not thread safe, thus developers have to deal with concurrency issue while using date. The new date-time API is immutable and does not have setter methods.
  

Java 8 - Base64

With Java 8, Base64 has finally got its due. Java 8 now has inbuilt encoder and decoder for Base64 encoding. In Java 8, we can use three types of Base64 encoding −

Java 8 Questions and Answers

Java 8 Questions and Answers has been designed with a special intention of helping students and professionals preparing for various Certification Exams and Job Interviews. This section provides a useful collection of sample Interview Questions and Multiple Choice Questions (MCQs) and their answers with appropriate explanations.

Java 8 - Quick Guide

Java 8 - Overview

JAVA 8 is a major feature release of JAVA programming language development. Its initial version was released on 18 March 2014. With the Java 8 release, Java provided supports for functional programming, new JavaScript engine, new APIs for date time manipulation, new streaming API, etc.

Java 8 - Useful Resources

The following resources contain additional information on Java8. Please use them to get more in-depth knowledge on this tpoic.

Discuss Java 8

Java 8 is the most awaited and is a major feature release of Java programming language. This is an introductory tutorial that explains the basic-to-advanced features of Java 8 and their usage in a simple and intuitive way.

Java 8 - Overview

JAVA 8 (aka jdk 1.8) is a major release of JAVA programming language development. Its initial version was released on 18 March 2014. With the Java 8 release, Java provided support for functional programming, new JavaScript engine, new APIs for date time manipulation, new streaming API, etc.

Java 8 - Environment Setup

Try it Option Online

We have set up the Java Programming environment online, so that you can compile and execute all the available examples online. It gives you confidence in what you are reading and enables you to verify the programs with different options. Feel free to modify any example and execute it online.

Java 8 - Lambda Expressions

Lambda expressions are introduced in Java 8 and are touted to be the biggest feature of Java 8. Lambda expression facilitates functional programming, and simplifies the development a lot.

Java 8 - Method References

Method references help to point to methods by their names. A method reference is described using :: (double colon) symbol. A method reference can be used to point the following types of methods −

Java 8 - Functional Interfaces

Functional interfaces have a single functionality to exhibit. For example, a Comparable interface with a single method ‘compareTo’ is used for comparison purpose. Java 8 has defined a lot of functional interfaces to be used extensively in lambda expressions. Following is the list of functional interfaces defined in java.util.Function package.