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In this blog post, I will be explaining how the Java 8 functional interface LongConsumer works. To know more about functional interfaces, you can refer this blog post. Edit The LongConsumer interface provides a method called accept . It accepts a single parameter of long data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameter passed in.The LongConsumer interface is a specialization of the Consumer  interface. While the Consumer interface accepts any data type, the LongConsumer interface accepts a long value. To see an example of the Consumer interface, refer to  this  blog post. LongConsumer Example Consider the following code snippet: public class LongConsumerDemo { public static void main(String args[]) { LongConsumer decrementBy5 = (num) -> System.out.println("Input:"+num+", Incremented Value:"+(num-5)); decrementBy5.accept(12); decrementBy5.accept(23); }}   Here, the Lon...

In this blog post, I will be explaining how the Java 8 functional interface IntConsumer works. To know more about functional interfaces, you can refer this blog post. Edit The IntConsumer interface provides a method called accept. It accepts a single parameter of int data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameter passed in. The  IntConsumer interface is a specialization of the Consumer interface. While the Consumer interface accepts any data type, the  IntConsumer interface accepts an Integer value. To see an example of the Consumer interface, refer to  this  blog post. IntConsumer Example Consider the following code snippet: public class IntConsumerDemo { public static void main(String args[]) { IntConsumer incrementby5 = (num) -> System.out.println("Input:"+num+", Incremented Value:"+(num+5)); incrementby5.accept(12); incrementby5.accept(23); }}   Here, the IntConsumer....

In this blog post, I will be explaining how the Java 8 functional interface DoubleConsumer works. To know more about functional interfaces, you can refer this blog post. Edit The DoubleConsumer interface provides a method called accept. It accepts a single parameter of double data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameter passed in. The  DoubleConsumer  interface is a specialization of the Consumer interface. While the Consumer interface accepts any data type, the DoubleConsumer interface accepts a Double value. To see an example of the Consumer interface, refer to  this  blog post. DoubleConsumer Example Consider the following code snippet: public class DoubleConsumerDemo { public static void main(String args[]) { DoubleConsumer squareGenerator = (num) -> System.out.println(num*num); double input = 5.0; squareGenerator.accept(input); }}   Here, the DoubleConsumer.accept method accepts a...

In this blog post, I will be explaining how the Java 8 functional interface BiFunction works. To know more about functional interfaces, you can refer  this  blog post. Edit The BiFunction is a specialization of the Function interface that accepts 2 arguments. Just like Function it provides a method called apply. This method accepts 2 arguments of any data type and returns a result. So it basically applies the logic in the apply method to the input parameters and returns the result. BiFunction Interface Example with two integer inputs and Integer output Consider the following code snippet: private static void example1(){ BiFunction<Integer,Integer,Integer> multiplier = (a,b) -> {return a*b;}; int input1 = 6; int input2 = 8; System.out.println("Result of multiplying "+input1+" and "+input2 +" is "+multiplier.apply(input1,input2) ); } Here, we have written a BiFunction implementation that accepts 2 integer values, multiplies them and ret...

In this blog post, I will be explaining how the Java 8 functional interface UnaryOperator works. To know more about functional interfaces, you can refer this blog post. Edit The UnaryOperator interface extends the Function interface. It inherits the apply method in the Function interface. The lambda expression passed to the UnaryOperator is used to provide an implementation for the apply method in the Function interface.   UnaryOperator example with Integer data type. Consider the following code snippet: public class UnaryOperatorDemo {public static void main(String[] args) {UnaryOperator<Integer> increaseBy5 = num -> num+5;System.out.println("Output with input 7 is "+increaseBy5.apply(7));}} Here, we have implemented the UnaryOperator.apply method using a lambda expression.  This method simply increases the value of the input number by 5 and returns it. So when you execute this code, it will print the following output: Output with input 7 is 12 UnaryO...

In this blog post, I will be explaining how the Java 8 functional interface Function works. To know more about functional interfaces, you can refer  this  blog post. Edit The Function interface provides a method called apply. It accepts a single parameter of any data type and returns a result of any data type. So it basically applies the logic in the apply method to the input parameter and returns the result. Function Interface Example with String Input and Integer return type Consider the following code snippet: public class FunctionDemo {public static void main(String[] args) {Function<String,Integer> lengthChecker = (str) -> {return str.length();};String input = "Hello World";System.out.println("Length of "+input+" is "+lengthChecker.apply(input) );input = "Test";System.out.println("Length of "+input+" is "+lengthChecker.apply(input) );}} Here, we have written a Function implementation that accepts a String ...

In this blog post, I will be explaining how the Java 8 functional interface BiPredicate works. To know more about functional interfaces, you can refer to this blog post. Edit The BiPredicate interface provides a method called test. This method accepts two parameters of any data type and returns a boolean. The BiPredicate interface is a specialization of the Predicate interface. While the Predicate interface accepts a single argument of any data type, the BiPredicate interface accepts two parameters of any data type. To see an example of the Predicate interface, refer to  this  blog post. BiPredicate method with Two Integer arguments Consider the following code snippet: public class BiPredicateDemo {public static void main(String[] args) {BiPredicate<String,String> isSubString = (str1,str2) -> {return (str1.indexOf(str2)>0 || str1.startsWith(str2));};System.out.println("Hello World has substring as Hello = "+isSubString.test("Hello World","Hel...

In this blog post, I will be explaining how the Java 8 functional interface Consumer works. To know more about functional interfaces, you can refer this blog post. Edit The Consumer interface provides a method called accept. It accepts a single parameter of any data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameter passed in. Consumer example with Integer parameter Consider the following code snippet: public class ConsumerDemo {public static void main(String args[]){Consumer<Integer> squareGenerator = (input) -> System.out.println("Square of "+input +" is "+(input*input));squareGenerator.accept(6);}}} Here, we have implemented the Consumer.accept method using a lambda expression.  This accept method accepts an Integer argument. It squares it and prints the result to the console. So when this code is executed, it will print the following output: Square of 6 is 36 Consumer example with ...

Java 8 introduced the concept of functional interfaces. In this blog post, I will be explaining what a Java 8 functional interface is. Edit What is a functional interface? A functional interface is nothing but an interface that has only one abstract method. It can have more than one static and default methods, but it should have only one abstract method in order to qualify as a functional interface. Consider the following code snippet: package learnjava.java8;@FunctionalInterfacepublic interface MyFunctionalInterface {public void method1();public default void defaultMethod(){System.out.println("Default method");}public default void staticMethod(){System.out.println("Static method");}} Here, we have defined an interface called  MyFunctionalInterface . This has only one abstract method called method1 and so this is a functional interface. It also has a default and a static method. Note that we have specified the @FunctionalInterface annotation. This annotati...

In this blog post, I will be explaining how the Java 8 functional interface BooleanSupplier works. To know more about functional interfaces, you can refer  this  blog post. Edit The  BooleanSupplier interface provides a method called getAsBoolean. This method does not accept any arguments. It returns a boolean value. The BooleanSupplier interface is a specialization of the Supplier interface that returns a boolean. To see an example of the Supplier  interface, refer to  this  blog post. BooleanSupplier example Consider the following code snippet: public class BooleanSupplierExample {public static void main(String[] args) {BooleanSupplier booleanSupplier = () -> true;System.out.println("Boolean flag = "+booleanSupplier.getAsBoolean());}} Here, we have implemented the getAsBoolean method using a lambda expression. This simply returns the value true. So when this code is executed, it will print the following output: Boolean flag = true You can get the source code for th...

In this blog post, I will be explaining how the Java 8 functional interface Predicate works. To know more about functional interfaces, you can refer this blog post. Edit The Predicate interface provides a method called test. This method accepts a parameter of any data type and returns a boolean. Predicate method with Integer argument Consider the following code snippet: public class PredicateDemo {public static void main(String[] args) {Predicate<Integer> greaterThan8 = (input) -> input > 8;System.out.println("4 is greater than 8 = "+greaterThan8.test(4));System.out.println("12 is greater than 8 = "+greaterThan8.test(12));}} Here, the Predicate.test method checks if the input number is greater than 8. So when the above code is executed, it will print the following output: 4 is greater than 8 = false12 is greater than 8 = true Predicate method with String argument Consider the following code snippet: import java.util.function.Predicate;public class...

In this blog post, I will be explaining how the Java 8 functional interface Supplier works. To know more about functional interfaces, you can refer this blog post. Edit The Supplier interface provides a method called get.  This method does not accept any arguments. It can return any data type. Supplier example with Integer return type. Consider the following code snippet: public static void main(String[] args) {Supplier<Integer> getRandom = () -> new Random().nextInt(100);System.out.println("Random number 1 = "+getRandom.get());System.out.println("Random number 2 = "+getRandom.get());} Here, we have implemented the Supplier.get method using a lambda expression.  This get method simple returns a random integer less than 100. So when this code is executed, it will print the following output: Random number 1 = 98Random number 2 = 89 Supplier example with Date as return type Consider the following code snippet: public class SupplierDemo {public static vo...