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Sample code to execute jar file from Java Program. Pre-requisite 1. Need to have executable jar file. 2. Copy the code in your workspace and Run the code. package com.test.reusable.enterprise.service; import java.io.BufferedReader; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import org.apache.commons.lang.exception.ExceptionUtils; public class ExecuteJarFile { public static void main(String[] args) { try { //Method1 to Execute Jar file From Java Program ProcessBuilder pb = new ProcessBuilder("java", "-jar", "HelloWorld.jar"); // command to execute jar file with fileName.jar pb.redirectErrorStream(true); pb.directory(new File("C:/www/")); // Directory path where your jar file is placed. Process p = pb.start();

var regex = /^([a-zA-Z0-9])+([\w_\.\-]([a-zA-Z0-9])*[a-zA-Z0-9])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/; Simple code to demonstrate to Read and Write text file in Java. package email; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; public class ReadAndWriteFile { public static void main(String[] args) {   try {         String content = "This is the content to write into file";          File writeFile = new File("D:/Sample.txt");    // if file doesnt exists, then create it    if (!writeFile.exists()) {     writeFile.createNewFile();    } /**   * When we pass true as parameter to FilwWriter   * then it appends the content in file instead of overwriting the content   */    //FileWriter fw = new FileWriter(file.getAbsoluteFile(),true);    FileWriter fw = new FileW