In this post, we will see about Java 9 process API improvements.
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Table of Contents<\/p>
Process class<\/code> and two new interfaces ProcessHandle<\/code> and ProcessHandle.Info<\/code>. These methods are used to create a new process and get process information like process status, running time, process id, etc. We can also get the current running process and its information.<\/p>\nThe Process Class<\/span><\/h2>\nJava Process<\/code> class is located in java.lang package<\/code> and provides methods to control the processes started by ProcessBuilder.start<\/code> and Runtime.exec<\/code>.<\/p>\nStart a new Process?<\/span><\/h3>\nWe can call start()<\/code> method of ProcessBuilder<\/code> class to start a new process. It will return an instance of Process<\/code> class that further can be used to get process-related information.<\/p>\n\nProcess process = new ProcessBuilder(\"vim\").start(); \/\/ vim is an editor in Linux\n<\/pre>\nMethods<\/span><\/h3>\nAlthough Process<\/code> class contains several methods but here we are listing the new methods added into Java 9 version. <\/p>\n\n\n\n\n\tMethod<\/th> Description<\/th>\n<\/tr>\n<\/thead>\n \n\n\tboolean supportsNormalTermination()<\/td> It returns true if the implementation of destroy() is to normally terminate the process, else returns false.<\/td>\n<\/tr>\n \n\tProcessHandle toHandle()<\/td> It returns a ProcessHandle for the Process.<\/td>\n<\/tr>\n \n\tlong pid()<\/td> It returns the native process ID of the process.<\/td>\n<\/tr>\n \n\tStream children()<\/td> It returns a snapshot of the direct children of the process.<\/td>\n<\/tr>\n \n\tStream descendants()<\/td> It returns a snapshot of the descendants of the process.<\/td>\n<\/tr>\n \n\tProcessHandle.Info info()<\/td> It returns a snapshot of information about the process.<\/td>\n<\/tr>\n \n\tCompletableFuture onExit()<\/td> It returns a CompletableFuture for the termination of the Process.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\nExample to get Process Id<\/span><\/h3>\nAfter creating a process (in the above example), we are getting process id using pid()<\/code> method of Process<\/code> class. See the example below.<\/p>\n\nimport java.io.IOException;\n\npublic class Main{\n public static void main(String[] args) throws IOException {\n Process process = new ProcessBuilder(\"vim\").start();\n \/\/ Get process id\n System.out.println(process.pid());\n }\n}\n<\/pre>\nOutput<\/p>\n
\nProcess Id: 10754\n<\/div>\nExample to get Process Information<\/span><\/h3>\nHere is an example to get more information about the process such as hashcode, children and class.<\/p>\n
\nimport java.io.IOException;\n\npublic class Main{\n public static void main(String[] args) throws IOException {\n Process process = new ProcessBuilder(\"vim\").start();\n \/\/ Get created process info\n System.out.println(process.pid());\n System.out.println(process.info());\n System.out.println(process.hashCode());\n System.out.println(process.isAlive());\n System.out.println(process.children());\n System.out.println(process.getClass());\n System.out.println(process.descendants().count());\n }\n}\n<\/pre>\nOutput<\/p>\n