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Articles by Maruthi Krishna
Page 19 of 50
Why can't we use the "super" keyword is in a static method in java?
A static method or, block belongs to the class and these will be loaded into the memory along with the class. You can invoke static methods without creating an object. (using the class name as reference).Where the "super" keyword in Java is used as a reference to the object of the superclass. This implies that to use "super" the method should be invoked by an object, which static methods are not.Therefore, you cannot use the "super" keyword from a static method.ExampleIn the following Java program, the class "SubClass" contains a private variable name with setter and getter methods and an ...
Read MoreHow to create a Dialog in JavaFX?
A Dialog is a graphical element, a window that shows information to the window and receives a response. You can create a dialog by instantiating the javafx.scene.control.Dialog class.ExampleThe following Example demonstrates the creation of a Dialog.import javafx.application.Application; import javafx.geometry.Insets; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.control.ButtonBar.ButtonData; import javafx.scene.control.ButtonType; import javafx.scene.control.Dialog; import javafx.scene.layout.HBox; import javafx.stage.Stage; import javafx.scene.paint.Color; import javafx.scene.text.Font; import javafx.scene.text.FontPosture; import javafx.scene.text.FontWeight; import javafx.scene.text.Text; public class DialogExample extends Application { @Override public void start(Stage stage) { //Creating a dialog Dialog dialog = new Dialog(); //Setting the title ...
Read MoreHow to host a web-service using IIS (windows) and .net
A web service is any piece of software which offers service to other systems. It makes itself available over the internet and uses a standardized XML or, JSON messaging system. A web service enables communication among various applications by using open standards such as HTML, XML, WSDL, and SOAP.IISIIS stands for, Internet Information Services, it is a web service software create by Microsoft. It is available with the Windows (NT) operating systems, it supports HTTP, HTTP/2, HTTPS, FTP, FTPS, SMTP and NNTP.Here we are going to discuss how create and launch a web service locally and send request to it.Installing ...
Read MoreHow to search a directory with file extensions in Java?
Following example prints the files in a directory based on the extensions −Exampleimport java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.stream.Stream; public class Demo { public static void main(String[] args) throws IOException { Stream path = Files.walk(Paths.get("D:\ExampleDirectory")); System.out.println("List of PDF files:"); path = path.filter(var -> var.toString().endsWith(".pdf")); path.forEach(System.out::println); path = Files.walk(Paths.get("D:\ExampleDirectory")); System.out.println("List of JPG files:"); path = path.filter(var -> var.toString().endsWith(".jpg")); path.forEach(System.out::println); path = Files.walk(Paths.get("D:\ExampleDirectory")); ...
Read MoreHow to read all files in a folder to a single file using Java?
The listFiles() method of the File class returns an array holding the objects (abstract paths) of all the files (and directories) in the path represented by the current (File) object.To read the contents of all the files in a folder into a single file −Create a file object by passing the required file path as a parameter.Read the contents of each file using Scanner or any other reader.Append the read contents into a StringBuffer.Write the StringBuffer contents into the required output file.Exampleimport java.io.DataOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.util.Scanner; public class Test { public static void main(String ...
Read MoreHow to get the list of jpg files in a directory in Java?
The String[] list(FilenameFilter filter) method of a File class returns a String array containing the names of all the files and directories in the path represented by the current (File) object. But the retuned array contains the filenames which are filtered based on the specified filter. The FilenameFilter is an interface in Java with a single method.accept(File dir, String name)To get the file names based on extensions implement this interface as such and pass its object to the above specified list() method of the file class.Assume we have a folder named ExampleDirectory in the directory D with 7 files and 2 directories ...
Read MoreHow to inherit multiple interfaces in Java?
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Just like classes you can extend one interface from another using the extends keyword. You can also extend multiple interfaces from an interface using the extends keyword, by separating the interfaces using comma (, ) as −interface MyInterface extends ArithmeticCalculations, MathCalculations{ExampleFollowing is the Java program demonstrating, how to extend multiple interfaces from a single interface.interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations { public abstract double ...
Read MoreWhat is the difference between Java and Java EE
JSE (Java Standard Edition)By using JavaSE you can develop stand-alone application ex: adobe reader, anti-virus, media players, etc. Java SE is also known as core java.lang: Language basics.util: Collection framework, events, data structure and other utility classes such as date.io: File operations, and other input and output operations.math: Multi precision arithmetics.nio: Non-blocking I/O framework for Java.net: Classes an API’s related to networking.security: This package provides classes and interfaces such as key generation, encryption, and decryption which belongs to the security framework.sql: Classes and interfaces for accessing/manipulating the data stored in databases and data sources.awt: Classes and interfaces to create GUI ...
Read MoreWhile chaining, can we throw unchecked exception from a checked exception in java?
When an exception is cached in a catch block, you can re-throw it using the throw keyword (which is used to throw the exception objects).While re-throwing exceptions you can throw the same exception as it is with out adjusting it as −try { int result = (arr[a])/(arr[b]); System.out.println("Result of "+arr[a]+"/"+arr[b]+": "+result); }catch(ArithmeticException e) { throw e; }Or, wrap it within a new exception and throw it. When you wrap a cached exception within another exception and throw it, it is known as exception chaining or, exception wrapping, by doing this you can adjust your exception, throwing higher ...
Read MoreIs there any method to convert a Set to immutable in Java
Whenever you need to create an object which cannot be changed after initialization you can define an immutable object. There are no specific rules to create immutable objects, the idea is to restrict the access of the fields of a class after initialization.A Set is an interface in collection framework, which does not allow duplicate values.Method to convert a set to immutableYes, Java provides a method named unmodifiableSet() in the Collections class. This method accepts a collection object as a parameter and returns an unmodifiable i.ie immutable form of it.ExampleIn the following Java program, we have created a HashSet object ...
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