Java Articles - Page 118 of 440

JShell implements REPL (Read-Evaluate-Print Loop) that reads the code from the command-line, evaluates the given snippet, and prints the result back to us.In JShell, it's possible to edit code from the default JShell editor by using JShell Editor Pad. We can also use the "/set" command to modify the default editor in order to define another one. When launching the "/edit" command, this editor can be used. In order to perform this operation, we can simply launch the "/set editor [editor]" command.Suppose we want to set the Notepad application as the default program for editing code, then just type the command: "/set editor ... Read More

The module is a named, self-describing collection of code and data. The code has been organized as a set of packages containing types like Java classes and interfaces. The data includes resources and other kinds of static information. We need to declare a module then add module-info.java at the root of the source code.Below is the template of the "module-info.java" file.module {    requires ;    requires ;    exports ;    exports ;    exports to }We can use certain command-line options that help us to modify existing modules and add dependencies to them, export ... Read More

JShell is an interactive command-line tool introduced in Java 9. It is also called a REPL tool that takes input, evaluates it, and prints output to the user.In the JShell tool, it's possible to list all variables created by using the internal command "/vars". We have different "/vars" commands available in the JShell tool as listed below./vars /vars [ID] /vars [Variable_Name] /vars -start /vars -all/vars: This command allows to us display the list of all active variables of the current session./vars [ID]: This command displays the variable and its value, corresponding to the entered ID. This ID corresponds to the name of ... Read More

A module that provides the implementation for the Service interface contains a "provides" statement in the module descriptor file. If the module doesn’t have the "provides" statement in the module descriptor file, the service loader can't load that module.We can create the Service Provider Interface by using below steps:We create a new Module com.tutorialspoint.serviceproviderinterface.In the src/main/java directory, we create "module-info.java" file.Inside our source directory, we create the package com.tutorialspoint.serviceproviderinterface.spi.Finally, we create the interface ServiceProviderInterface that contains a method: printServiceName() to be implemented.In the below, we can define Service Provider Interface.package com.tutorialspoint.serviceproviderinterface.spi; public interface ServiceProviderInterface {    void printServiceName(); }Read More

You can compute the bitwise conjunction between two images using the bitwise_not() method of the org.opencv.core.Core class.This method accepts two Mat objects representing the source and destination matrices, calculates the inverse of each element in the source matrix and stores the result in the destination matrix.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.highgui.HighGui; import org.opencv.imgcodecs.Imgcodecs; public class BitwiseNOTExample {    public static void main(String args[]) throws Exception {       //Loading the OpenCV core library       System.loadLibrary( Core.NATIVE_LIBRARY_NAME );       //Reading the Image       String file ="D://images//elephant.jpg";       Mat src = Imgcodecs.imread(file);   ... Read More

A digital image is stored as a 2D array of pixels and a pixel is the smallest element of a digital image.Each pixel contains the values of alpha, red, green, blue values and the value of each color lies between 0 to 255 which consumes 8 bits (2^8).The ARGB values are stored in 4 bytes of memory in the same order (right to left) with blue value at 0-7 bits, Green value at 8-15 bits, Red value at 16-23 bits and, alpha at 24-31 bits.Retrieving the pixel contents (ARGB values) of an image −To get the pixel values from an ... Read More

You can draw makers on an image using the drawMarker() method of the org.opencv.imgproc.Imgproc class. This method accepts the following parameters −img − A Mat object representing the input image.position − An object of the class Point to specify the position of the marker.color − An object of the class Scalar to specify the color of the marker.markerType − An integer constant specifying the type of the marker.size − An integer value specifying the size of the marker.thickness − An integer value specifying the thickness of the marker.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.Scalar; import org.opencv.highgui.HighGui; import org.opencv.imgcodecs.Imgcodecs; import ... Read More

The detect() method of the org.opencv.features2d.Feature2D (abstract) class detects the key points of the given image. To this method, you need to pass a Mat the object representing the source image and an empty MatOfKeyPoint object to hold the read key points.You can draw the draw key points on the image using the drawKeypoints() method of the org.opencv.features2d.Features2d class.NoteSince Feature2D is an abstract class you need to instantiate one of its subclasses to invoke the detect() method. Here we have used the FastFeatureDetector class.Features2D and Features2d are two different classes of the package features2d don’t get confused...Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; ... Read More

Contours are nothing but the line joining all the points along the boundary of a particular shape. Using this you can −Find the shape of an object.Calculate the area of an object.Detect an object.Recognize an object.You can find the contours of various shapes, objects in an image using the findContours() method. In the same way you can drawYou can also find the area of the shapes in the given input images. To do so you need to invoke the contourArea() method of the Imgproc class. This method accepts the contour of a particular shape, finds and returns its area.ExampleFollowing java ... Read More

Contours are nothing but the line joining all the points along the boundary of a particular shape. Using this you can −Find the shape of an object.Calculate the area of an object.Detect an object.Recognize an object.You can find the contours of various shapes, objects in an image using the findContours() method. This method accepts the following parameters −A binary image.An empty list object of type MatOfPoint to store the contours.An empty Mat object to store the image topology.Two integer variables to specify the mode and method to find the contours of the given image.Exampleimport java.util.ArrayList; import java.util.Iterator; import java.util.List; import ... Read More