Oracle released a new version of Java as Java 8 in March 18, 2014. It was a revolutionary release of the Java for software development platform. It includes various upgrades to the Java programming, JVM, Tools and libraries.
Java 8 Programming Language Enhancements
Java 8 provides following features for Java Programming:
- Lambda expressions,
- Method references,
- Functional interfaces,
- Stream API,
- Default methods,
- Base64 Encode Decode,
- Static methods in interface,
- Optional class,
- Collectors class,
- ForEach() method,
- Parallel array sorting,
- Nashorn JavaScript Engine,
- Parallel Array Sorting,
- Type and Repating Annotations,
- IO Enhancements,
- Concurrency Enhancements,
- JDBC Enhancements etc.
Lambda Expressions
Lambda expression helps us to write our code in functional style. It provides a clear and concise way to implement SAM interface(Single Abstract Method) by using an expression. It is very useful in collection library in which it helps to iterate, filter and extract data.
Method References
Java 8 Method reference is used to refer method of functional interface . It is compact and easy form of lambda expression. Each time when you are using lambda expression to just referring a method, you can replace your lambda expression with method reference.
Functional Interface
An Interface that contains only one abstract method is known as functional interface. It can have any number of default and static methods. It can also declare methods of object class.
Functional interfaces are also known as Single Abstract Method Interfaces (SAM Interfaces).
Optional
Java introduced a new class Optional in Java 8. It is a public final class which is used to deal with NullPointerException in Java application. We must import java.util package to use this class. It provides methods to check the presence of value for particular variable.
forEach
Java provides a new method forEach() to iterate the elements. It is defined in Iterable and Stream interfaces.
It is a default method defined in the Iterable interface. Collection classes which extends Iterable interface can use forEach() method to iterate elements.
This method takes a single parameter which is a functional interface. So, you can pass lambda expression as an argument.
Date/Time API
Java has introduced a new Date and Time API since Java 8. The java.time package contains Java 8 Date and Time classes.
Default Methods
Java provides a facility to create default methods inside the interface. Methods which are defined inside the interface and tagged with default keyword are known as default methods. These methods are non-abstract methods and can have method body.
Nashorn JavaScript Engine
Nashorn is a JavaScript engine. It is used to execute JavaScript code dynamically at JVM (Java Virtual Machine). Java provides a command-line tool jjs which is used to execute JavaScript code.
You can execute JavaScript code by two ways:
- Using jjs command-line tool, and
- By embedding into Java source code.
StringJoiner
Java added a new final class StringJoiner in java.util package. It is used to construct a sequence of characters separated by a delimiter. Now, you can create string by passing delimiters like comma(,), hyphen(-) etc.
Collectors
Collectors is a final class that extends Object class. It provides reduction operations, such as accumulating elements into collections, summarizing elements according to various criteria etc.
Stream API
Java 8 java.util.stream package consists of classes, interfaces and an enum to allow functional-style operations on the elements. It performs lazy computation. So, it executes only when it requires.
Stream Filter
Java stream provides a method filter() to filter stream elements on the basis of given predicate. Suppose, you want to get only even elements of your list, you can do this easily with the help of filter() method.
This method takes predicate as an argument and returns a stream of resulted elements.
Java Base64 Encoding and Decoding
Java provides a class Base64 to deal with encryption and decryption. You need to import java.util.Base64 class in your source file to use its methods.
This class provides three different encoders and decoders to encrypt information at each level.
Java Parallel Array Sorting
Java provides a new additional feature in Arrays class which is used to sort array elements parallelly. The parallelSort() method has added to java.util.Arrays class that uses the JSR 166 Fork/Join parallelism common pool to provide sorting of arrays. It is an overloaded method.
