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It REPRESENTS a FUNCTION that PRODUCES a long-valued RESULT.

It represents a function that produces a long-valued result.

It REPRESENTS a FUNCTION that ACCEPTS TWO arguments and produces a long-valued RESULT.

It represents a function that accepts two arguments and produces a long-valued result.

It REPRESENTS a FUNCTION that PRODUCES an int-valued RESULT.

It represents a function that produces an int-valued result.

It REPRESENTS a function that ACCEPTS two ARGUMENTS and PRODUCES an int-valued RESULT.

It represents a function that accepts two arguments and produces an int-valued result.

It REPRESENTS a FUNCTION that PRODUCES a double-valued RESULT.

It represents a function that produces a double-valued result.

It REPRESENTS a function that ACCEPTS two ARGUMENTS and PRODUCES a double-valued result.

It represents a function that accepts two arguments and produces a double-valued result.

It REPRESENTS a SUPPLIER of RESULTS.

It represents a supplier of results.

It REPRESENTS a PREDICATE (Boolean-valued FUNCTION) of ONE ARGUMENT.

It represents a predicate (Boolean-valued function) of one argument.

It REPRESENTS an OPERATION that ACCEPTS an object-valued and a long-valued argument, and RETURNS no result.

It represents an operation that accepts an object-valued and a long-valued argument, and returns no result.

It REPRESENTS an operation that ACCEPTS an object-valued and an int-valued argument, and RETURNS no result.

It represents an operation that accepts an object-valued and an int-valued argument, and returns no result.

It represents an operation that ACCEPTS an object-valued and a double-valued ARGUMENT, and returns no RESULT.

It represents an operation that accepts an object-valued and a double-valued argument, and returns no result.

It represents an operation on a SINGLE long-valued OPERAND that PRODUCES a long-valued RESULT.

It represents an operation on a single long-valued operand that produces a long-valued result.

It represents a FUNCTION that ACCEPTS a long-valued ARGUMENT and PRODUCES an int-valued result.

It represents a function that accepts a long-valued argument and produces an int-valued result.

It represents a function that accepts a long-valued ARGUMENT and PRODUCES a double-valued RESULT.

It represents a function that accepts a long-valued argument and produces a double-valued result.

It REPRESENTS a SUPPLIER of long-valued RESULTS.

It represents a supplier of long-valued results.

It REPRESENTS a PREDICATE (Boolean-valued FUNCTION) of ONE long-valued ARGUMENT.

It represents a predicate (Boolean-valued function) of one long-valued argument.

It represents a FUNCTION that accepts a long-valued argument and PRODUCES a RESULT.

It represents a function that accepts a long-valued argument and produces a result.

It represents an OPERATION that ACCEPTS a single long-valued ARGUMENT and RETURNS no RESULT.

It represents an operation that accepts a single long-valued argument and returns no result.

It represents an operation UPON TWO long-valued operands and produces a long-valued RESULT.

It represents an operation upon two long-valued operands and produces a long-valued result.

It REPRESENTS an OPERATION on a SINGLE int-valued OPERAND that produces an int-valued result.

It represents an operation on a single int-valued operand that produces an int-valued result.

It REPRESENTS a function that ACCEPTS an int-valued ARGUMENT and produces a long-valued result.

It represents a function that accepts an int-valued argument and produces a long-valued result.

It REPRESENTS a FUNCTION that ACCEPTS an int-valued argument and PRODUCES a double-valued result.

It represents a function that accepts an int-valued argument and produces a double-valued result.

It REPRESENTS a SUPPLIER of int-valued RESULTS.

It represents a supplier of int-valued results.

It REPRESENTS a PREDICATE (Boolean-valued FUNCTION) of ONE int-valued ARGUMENT.

It represents a predicate (Boolean-valued function) of one int-valued argument.

It represents a FUNCTION that ACCEPTS an int-valued ARGUMENT and produces a RESULT.

It represents a function that accepts an int-valued argument and produces a result.

It REPRESENTS an OPERATION that accepts a SINGLE int-valued argument and returns no RESULT.

It represents an operation that accepts a single int-valued argument and returns no result.

It REPRESENTS an operation UPON two int-valued OPERANDS and PRODUCES an int-valued result.

It represents an operation upon two int-valued operands and produces an int-valued result.

It REPRESENTS a function that accepts one argument and PRODUCES a RESULT.

It represents a function that accepts one argument and produces a result.

It represents an operation on a SINGLE double-valued operand that produces a double-valued RESULT.

It represents an operation on a single double-valued operand that produces a double-valued result.

It represents a function that ACCEPTS a double-valued ARGUMENT and produces a long-valued RESULT.

It represents a function that accepts a double-valued argument and produces a long-valued result.

It REPRESENTS a function that accepts a double-valued ARGUMENT and produces an int-valued RESULT.

It represents a function that accepts a double-valued argument and produces an int-valued result.

It REPRESENTS a SUPPLIER of double-valued RESULTS.

It represents a supplier of double-valued results.

It REPRESENTS a PREDICATE (Boolean-valued FUNCTION) of ONE double-valued ARGUMENT.

It represents a predicate (Boolean-valued function) of one double-valued argument.

It REPRESENTS a FUNCTION that accepts a double-valued ARGUMENT and PRODUCES a result.

It represents a function that accepts a double-valued argument and produces a result.

It represents an operation that accepts a SINGLE double-valued ARGUMENT and RETURNS no RESULT.

It represents an operation that accepts a single double-valued argument and returns no result.

It represents an OPERATION upon two double-valued OPERANDS and PRODUCING a double-valued RESULT.

It represents an operation upon two double-valued operands and producing a double-valued result.

It represents an OPERATION that accepts a single input argument and RETURNS no RESULT.

It represents an operation that accepts a single input argument and returns no result.

It REPRESENTS a SUPPLIER of Boolean-valued RESULTS.

It represents a supplier of Boolean-valued results.

It REPRESENTS a PREDICATE (Boolean-valued FUNCTION) of TWO ARGUMENTS.

It represents a predicate (Boolean-valued function) of two arguments.

It REPRESENTS an operation UPON TWO OPERANDS of the same type, producing a RESULT of the same type as the operands.

It represents an operation upon two operands of the same type, producing a result of the same type as the operands.

It represents a function that ACCEPTS TWO ARGUMENTS and PRODUCES a RESULT.

It represents a function that accepts two arguments and produces a result.

It REPRESENTS an operation that ACCEPTS two input ARGUMENTS, and returns no RESULT.

It represents an operation that accepts two input arguments, and returns no result.

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.

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.

SYSTEM.out::println METHOD is a STATIC method reference to println method of out OBJECT of System CLASS.

System.out::println method is a static method reference to println method of out object of System class.

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 −

• STATIC methods
• Instance methods
• Constructors using NEW operator (TreeSet::new)

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 −

Using lambda expression, you can refer to final variable or effectively final variable (which is ASSIGNED only once). Lambda expression throws a COMPILATION error, if a variable is assigned a VALUE the second TIME.

Using lambda expression, you can refer to final variable or effectively final variable (which is assigned only once). Lambda expression throws a compilation error, if a variable is assigned a value the second time.

Lambda EXPRESSIONS are used primarily to define inline implementation of a functional interface, i.e., an interface with a single method only. In the above example, we've used VARIOUS types of lambda expressions to define the operation method of MathOperation interface. Then we have DEFINED the implementation of sayMessage of GreetingService.

Lambda expression eliminates the need of anonymous class and gives a very SIMPLE yet powerful functional programming capability to Java.

Lambda expressions are used primarily to define inline implementation of a functional interface, i.e., an interface with a single method only. In the above example, we've used various types of lambda expressions to define the operation method of MathOperation interface. Then we have defined the implementation of sayMessage of GreetingService.

Lambda expression eliminates the need of anonymous class and gives a very simple yet powerful functional programming capability to Java.

A lambda expression is characterized by the following syntax - PARAMETER −> expression body

Following are the important characteristics of a lambda expression −

• Optional type DECLARATION − No need to declare the type of a parameter. The COMPILER can inference the same from the value of the parameter.
• Optional parenthesis around parameter − No need to declare a single parameter in parenthesis. For multiple PARAMETERS, parentheses are required.
• Optional curly braces − No need to use curly braces in expression body if the body contains a single statement.
• Optional return keyword − The compiler automatically returns the value if the body has a single expression to return the value. Curly braces are required to indicate that expression returns a value.

A lambda expression is characterized by the following syntax - parameter −> expression body

Following are the important characteristics of a lambda expression −

FOLLOWING code sorts a list of string USING Java 8 lambda expression:

//sort using java 8
private void sortUsingJava8(List<String&GT; names){
Collections.sort(names, (s1, S2) -> s1.compareTo(s2));
}

Following code sorts a list of string using Java 8 lambda expression:

//sort using java 8
private void sortUsingJava8(List<String> names){
Collections.sort(names, (s1, s2) -> s1.compareTo(s2));
}

There are dozens of features added to JAVA 8, the most SIGNIFICANT ones are mentioned below −

• Lambda expression − Adds functional processing capability to Java.
• Method references − Referencing functions by their names instead of invoking them directly. Using functions as parameter.
• Default method − Interface to have default method implementation.
• New TOOLS − New compiler tools and utilities are added like 'jdeps' to figure out dependencies.
• Stream API − New stream API to facilitate pipeline processing.
• Date Time API − Improved date time API.
• Optional − Emphasis on best practices to handle null values properly.
• Nashorn, JavaScript Engine − A Java-based engine to execute JavaScript code.

Along with these new featuers, lots of FEATURE enhancements are done under-the-hood, at both compiler and JVM level.

There are dozens of features added to Java 8, the most significant ones are mentioned below −

Along with these new featuers, lots of feature enhancements are done under-the-hood, at both compiler and JVM level.