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Java Articles
Page 283 of 450
Package Imports in JShell of Java 9
In general, 10 packages are imported using the JShell.The following command shows the packages that were imported by default.jshell> /importOutputimport java.io.* import java.math.* import java.net.* import java.nio.file* import java.sql.* import java.util.* import java.util.regex* import java.util.function* import java.util.prefs* import java.util.stream.*Importing a specific package using JShelljshell> import java.util.*;
Read MoreHow to implement the Runnable interface using lambda expression in Java?
The Runnable interface is a functional interface defined in java.lang package. This interface contains a single abstract method, run() with no arguments. When an object of a class implementing this interface used to create a thread, then run() method has invoked in a thread that executes separately.Syntax@FunctionalInterface public interface Runnable { void run(); }In the below example, we can implement a Runnable interface by using an anonymous class and lambda expression.Examplepublic class RunnableLambdaTest { public static void main(String[] args) { Runnable r1 = new Runnable() { ...
Read MoreWhy Kotlin will replace Java for Android App Development
While working with Kotlin, Java libraries and frameworks can be used. This can be done with the help of advanced frameworks, without having to change the whole project. Java and Kotlin co-exist and can be present in the same project.Kotlin code can be placed inside Android Studio, without making the whole project in Kotlin.It is an open source platform that also helps in quick development of projects. It is easy, and readable, and considerably requires lesser coding in comparison to Java.Kotlin was developed by JetBrains, and IntelliJ is the IDE which Android Studio also uses.Kotlin plugin can be installed and ...
Read MoreHow to implement JavaFX event handling using lambda in Java?
JavaFX Button class provides the setOnAction() method that can be used to set an action for the button click event. An EventHandler is a functional interface and holds only one method is the handle() method.Syntax@FunctionalInterface public interface EventHandler extends EventListenerIn the below example, we can able to implement event handling of JavaFX by using a lambda expression.Exampleimport javafx.application.*; import javafx.beans.property.*; import javafx.event.*; import javafx.scene.*; import javafx.scene.control.*; import javafx.scene.layout.*; import javafx.stage.*; public class LambdaWithJavaFxTest extends Application { public static void main(String[] args) { Application.launch(args); } @Override public void start(Stage stage) throws Exception { ...
Read MoreHow to implement DoubleFunction using lambda expression in Java?
The DoubleFunction is a built-in functional interface defined in java.util.function package. This interface accepts one double-valued parameter as input and returns a value of type R. As this is a functional interface, it can be used as an assignment target for a lambda expression or method reference. DoubleFunction interface having only one abstract method, apply().Syntax@FunctionalInterface public interface DoubleFunction { R apply(double value); }Exampleimport java.util.function.DoubleFunction; public class DoubleFunctionTest { public static void main(String[] args) { DoubleFunction getGrade = marks -> { // lambda expression if(marks > 90 && marks 70 && marks 50 && marks
Read MoreHow to generate prime numbers using lambda expression in Java?
A prime number is a number that is greater than 1 and divided by 1 or itself only. It other words, it can't be divided by other numbers than itself or 1. The generation of prime numbers is 2, 3, 5, 7, 11, 13, 17 and etc.In the below example, we can generate the prime numbers with the help of Stream API and lambda expressions.Exampleimport java.util.*; import java.util.stream.*; public class PrimeNumberLambdaTest { public static void main(String[] args) { List generate = PrimeNumberLambdaTest.generate(10); System.out.println(generate); } public static List generate(int series) { Set set = new TreeSet(); ...
Read MoreHow to implement IntFunction with lambda expression in Java?
IntFunction interface is a functional interface in Java 8 and defined in java.util.function package. This interface accepts an int-valued parameter as input and returns a value of type R. IntFunction interface can be used as an assignment target for a lambda expression or method reference and holds only one abstract method, apply().Syntax@FunctionalInterface public interface IntFunction { R apply(int value); }Exampleimport java.util.HashMap; import java.util.Map; import java.util.function.IntFunction; public class IntFunctionTest { public static void main(String[] args) { IntFunction getMonthName = monthNo -> { // lambda expression ...
Read MoreHow to implement the Fibonacci series using lambda expression in Java?
The Fibonacci is a sequence of numbers in which every number after the first two numbers is the sum of the two preceding numbers like 0, 1, 1, 2, 3, 5, 8, 13, 21 and so on. The sequence of Fibonacci numbers defined by using "F(n)=F(n-1)+F(n-2)".In the below example, we can implement the Fibonacci series with the help of Stream API and lambda expression. The Stream.iterate() method returns an infinite sequential ordered stream produced by iterative application of a function to an initial element seed, producing a stream consisting of seed, f(seed), f(f(seed)), etc.Exampleimport java.util.List; import java.util.stream.*; public class FibonacciTest { public static void ...
Read MoreHow to sort a list using Comparator with method reference in Java 8?
Java 8 introduced changes in the Comparator interface that allows us to compare two objects. These changes help us to create comparators more easily. The first important method added is the comparing() method. This method receives as a parameter Function that determines the value to be compared and creates Comparator. Another important method is the thenComparing() method. This method can be used to compose Comparator.In the below example, we can sort a list by using the first name with comparing() method and then the last name with the thenComparing() method of Comparator interface.Exampleimport java.util.*; public class MethodReferenceSortTest { ...
Read MoreHow to populate a Map using a lambda expression in Java?
A Map is a collection object that maps keys to values in Java. The data can be stored in key/value pairs and each key is unique. These key/value pairs are also called map entries.In the below example, we can populate a Map using a lambda expression. We have passed Character and Runnable arguments to Map object and pass a lambda expression as the second argument in the put() method of Map class. We need to pass command-line arguments whether the user enters 'h' for Help and 'q' for quit with the help of Scanner class.Exampleimport java.util.*; public class PopulateUsingMapLambdaTest ...
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