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Java Articles
Page 276 of 450
Difference Between extends and implements keywords in Java
In this post, we will understand the differences between ‘Extends’ and ‘Implements’ keyword.ExtendsUsing this, a class can be used as a base class, and another class inherits this base class.An interface can also inherit other interfaces using this keyword.Only one superclass can be extended by a class.Any number of interfaces can be extended by an interface.It is not required for the subclass (that extends a superclass) to override all the methods in the superclass.Following is an example of the extends keyword −Exampleclass Super { ..... ..... } class Sub extends Super { ...
Read MoreDifference Between HashMap and LinkedHashMap in Java
In this post, we will understand the difference between HashMap and LinkedHashMap in Java.HashMapIn this structure, the order of insertion is not preserved.It uses the HashTable to store maps.It extends the ‘AbstractMap’.It implements the ‘Map’ interface.This was introduced in JDK 2.0.It has a relatively low overhead.LinkedHashMapIn this structure, the order of insertion is not preserved.It uses the HashTable and Linked List to store maps.It extends the ‘Hashmap’.It implements the ‘Map’ interface.This was introduced in JDK 4.0.It has a relatively higher overhead.This is because it has to maintain the order of entries in the map structure.
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 MoreMajority Element in Java
Let’s suppose we have given an array of integers. The task is to find the index of a particular element in the given array. For example, Input-1 −N = 8 A[ ] = { 1, 2, 4, 3, 3, 1, 1, 5}Output −1Explanation − In the given array of integers, the most appearing number is ‘1’. Thus the output is ‘1’.Input-2 −N = 6 A[ ] = {1, 5, 4, 4, 1, 1}Output −1Explanation − In the given array of integers, the most appearing number is ‘1’. Thus we can return the output ‘1’.Approach to solve this problemThe given array ...
Read MoreWrite a program in Java to find the missing positive number in a given array of unsorted integers
Let’s suppose we have given an array of unsorted integers. The task is to find the positive missing number which is not present in the given array in the range [0 to n]. For example, Input-1 −N = 9 arr = [0, 2, 5, 9, 1, 7, 4, 3, 6]Output −8Explanation − In the given unsorted array, ‘8’ is the only positive integer that is missing, thus the output is ‘8’.Input-2 −N = 1 arr = [0]Output −1Explanation − In the given array, ‘1’ is the only one positive integer which is missing, thus the output is ‘1’.Approach to solve ...
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 MoreHow to simulate Print screen button using selenium webdriver in Java?
We can simulate a Print screen button with Selenium. The screenshot is captured with the Print screen button. Capturing a screenshot is a three way process. It is an important step towards failure analysis.We shall convert the driver object to TakeScreenshot interface.SyntaxTakesScreenshot s = (TakesScreenshot)driver;Then, with the getScreenshotAs method we shall have an image file and copy that file to a location with FileUtils.copyFile method.SyntaxFile sp=s.getScreenshotAs(OutputType.FILE); FileUtils.copyFile(sp, new File("path of image file"));Exampleimport org.openqa.selenium.By; import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.chrome.ChromeDriver; import org.openqa.selenium.OutputType; import org.openqa.selenium.TakesScreenshot; import org.apache.commons.io.FileUtils; import java.io.File; public class PrintScreenSimulate { public static void main(String[] args) { ...
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