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Execute command displaying console window and also get handle of the process

I am trying to run a command from Java that will start a process that runs for several minutes. I need to just trigger the command and get the process handle and continue with other operations in a loop. At regular intervals, I will have to monitor that the process is still active.
I also need the console window to display to show the output of the process for the user.
Currently, I have tried methods from both Runtime and ProcessBuilder classes to run my command but neither of them has helped me achieve my objective.
Sample code:
//Changing the directory and running Maven exec: java command on the POM file in that directory.
String cmd = "cd C:/Test & mvn exec:java";
String finalCmd = "cmd /c \""+ cmd +"\"";
Process process = Runtime.getRuntime().exec(finalCmd);
Thread.sleep(10);
boolean alive = process.isAlive();
The value of variable alive is True, but I don't see the process got started. When the program execution is complete, only then the process starts and I am not sure why that happens.
Also to display the console window, I found from google that I need to use the below command:
String finalCmd = "cmd /c start cmd.exe /c \"" + cmd + "\"";
However, with this, the process starts immediately but I do not get the process handle as I find the alive variable shows false.
Does someone know how this objective can be achieved? I am ok if it's not possible to do both at the same time but at least I need to get the process execution to start and get the handle to monitor the process state later in my code.

Couple of things that are happening incorrectly here:
We need to pass our command as string tokens to the exec() command
We need to wait for the process to exit with process.waitFor() instead of sleeping, this will block the current thread so if you don't want that you need to execute this in another thread or use an ExecutorService.
Advisable to check the output value of waitFor() to see if our command executed properly (value of 0) or not (any other value,
typically a positive 1 in case of unsuccessful execution)
Optionally (to see the output) we need to redirect the standard OUT and ERR somewhere, say print it to console(), though you could put it to a file some GUI window etc.
So at a minimum the following code should work:
Process process = Runtime.getRuntime().exec(new String[] {"cmd", "/c", "cd", "C:\\dev", "&&", "dir"});
int outputVal = process.waitFor();
boolean alive = process.isAlive();
System.out.format("alive %s, outputVal: %d\n",alive, outputVal);
Further suggestions:
use ProcessBuilder instead of runTime.exec(), it allows more control
and is the recommended way since JDK 1.5
read the inputStream
So the code will look some thing like this:
List<String> cmdList = Arrays.asList("cmd", "/c", "cd", "C:\\dev", "&&", "dir");
ProcessBuilder pb = new ProcessBuilder(cmdList);
pb.redirectErrorStream(true); //redirect STD ERR to STD OUT
Process process = pb.start();
try (final BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
String line = null;
while ((line = br.readLine()) != null) {
System.out.println("std-out-line: " + line);
}
}
int outputVal = process.waitFor();
System.out.format("outputVal: %d\n", outputVal);
Since waitFor() is a blocking call, you can execute this in a separate thread or using an executorService. Sample code here:
final StringBuffer outputSb = new StringBuffer();
ExecutorService executorService = null;
try {
executorService = Executors.newSingleThreadExecutor();
final Future<Integer> future = executorService.submit(new Callable<Integer>() {
#Override
public Integer call() throws Exception {
try (final BufferedReader br = new BufferedReader(
new InputStreamReader(process.getInputStream()))) {
String line = null;
while ((line = br.readLine()) != null) {
outputSb.append("std-out-line: ");
outputSb.append(line);
outputSb.append('\n');
}
}
int exitValue = process.waitFor();
System.out.format("exitValue: %d\n", exitValue);
return exitValue;
}
});
while (!future.isDone()) {
System.out.println("Waiting for command to finish doing something else..");
Thread.sleep(1 * 1000);
}
int exitValue = future.get();
System.out.println("Output: " + outputSb);
} finally {
executorService.shutdown();
}

Here's a solution that uses WMIC.
public static void main( String[] args ) throws Exception {
// Vars
Process process;
String output;
// Execution
process = Runtime.getRuntime().exec("cmd /c wmic process call create calc.exe | findstr ProcessId");
output = readTrimmedOutput(process.getInputStream());
System.out.println("Output from command: " + output);
// Basic string manipulation to get process id
String str_proc_id = output.split(" = ")[1].replace(";","");
System.out.println("ProcessId is: " + str_proc_id);
// Some thread delay that you can comment/uncomment for testing if running or not
Thread.sleep(5000);
// Finding if process is still running
process = Runtime.getRuntime().exec("cmd /c wmic process get processid | findstr " + str_proc_id);
output = readTrimmedOutput(process.getInputStream());
boolean isRunning = output.contains(str_proc_id);
System.out.println("Is process still running? " + isRunning);
}
private static String readTrimmedOutput(InputStream is) throws Exception {
BufferedReader breader = new BufferedReader(new InputStreamReader(is));
String line = breader.readLine();
return line != null ? line.trim() : "";
}
Sample output
Output from command: ProcessId = 6480;
ProcessId is: 6480
Is process still running? true
For showing/displaying cmd console change some lines to:
// Execution
String your_command = "cmd.exe /c \"dir\"";
process = Runtime.getRuntime().exec("cmd /c wmic process call create \"" + your_command + "\" | findstr ProcessId");
References:
https://msdn.microsoft.com/en-us/library/aa394531(v=vs.85).aspx
https://www.computerhope.com/wmic.htm

since I didn't quite understand what you really need,i brought a comprehensive example of openning cmd from a java class (for instance class A) and starting a process of another java class (class B) and doing some operation from class B while class B is informing class A of whether it is processing yet or not. so the whole thing is to excecute class B from command promt that class A started and sending information from class B to A to notify it that it's still running.
in my example i took Main class as class A and myProcess class as class B.
as you can see in code below the Main class is Opening cmd and is executing myProcess class then myProcess class is sending a information about the process through the socket that was created in Main class
//imports
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
//class
public class Main
{
//fields
//methods
public static void main(String[] args) throws Exception
{
Runtime run = Runtime.getRuntime();
String new_dir = "C:\\Users\\Parsa\\Desktop\\New folder (2)";//imagine the directory of myProcess.class is in this folder
startServer();
run.exec("cmd.exe /c cd \""+new_dir+"\" & start cmd.exe /k \"java myProcess\"");
}
public static void startServer()
{
Thread myThread = new Thread()
{
#Override
public void run()
{
ServerSocket ss;// creating an open port for receiving data from network
try {
ss = new ServerSocket(60010);//open port number 60010--> it can really be anything that is empty
Socket s = ss.accept();//Listens for a connection to be made to this socket and accepts it
BufferedReader in = new BufferedReader(
new InputStreamReader(s.getInputStream()));//get the inputstream and change it to a buffered reader in order to get a string from remote network
String line = null;
while ((line = in.readLine()) != null) //read the input
{
System.out.println(line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
};
myThread.start();
}
}
myProcess class:
by the way you need to compile the myProcess class manually by command prompt and excecute myProcess.class file from Main class
and the myProcess class is
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.URL;
import java.net.URLConnection;
import java.net.UnknownHostException;
import java.util.Timer;
import java.util.TimerTask;
public class myProcess extends Thread
{
//field
//methods
public static void main(String[] args) throws Exception
{
System.out.println("myProcess has started");
startSender();
}
public static void startSender()
{
Thread myThread = new Thread()
{
#Override
public void run()
{
try
{
Socket s = new Socket("localhost", 60010);
BufferedWriter out = new BufferedWriter(
new OutputStreamWriter(s.getOutputStream()));
for(int i = 0 ; i<10 ; i++)
{
out.write("Process in running");
out.newLine();
out.flush();
Thread.sleep(200);
}
out.close();
//do whatever here
System.out.println("myProcess output");
}
catch (Exception e)
{
e.printStackTrace();
}
}
};
myThread.start();
if(!myThread.isAlive())
{
System.out.println("myProcess has finished");
}
}
}
since i didn't exactly understand what you wanted ,this is probably not exactly what you want, but... it will definitely help you if you manipulate the code.

I believe that you need to launch you application as the process and not the CMD and then launch a child process of the CMD. It is the same as in Linux.
The CMD that you launched is alive=true but when you started java from that CMD is another process which is a child of the CMD but it will not return you the expected results.
HTH,
Gal
PS. you might want to take a look at https://commons.apache.org/proper/commons-exec/ which is superior in functionality to Java in my opinion.

java: call external jar program (-> 'create process error')

I'm trying toopen/execute another program, which is a .jar file, but I'm getting the following error:
it is not a windows application
(java.io.IOException: CreateProcess error=193)
Here is my code:
import java.io.IOException;
public class Test8 {
public static void main(String[] args) {
try {
String filepath = "C://Users//Alex//Desktop//Speedtest.jar";
Process p = Runtime.getRuntime().exec(filepath);
} catch (IOException e) {
e.printStackTrace();
}
}
}

At the command-line, JARs are executed with java -jar. Try passing a String array:
String[] args = new String[] {"java", "-jar", "/path/to/myJar.jar"};
Process p = Runtime.getRuntime().exec(args);

Compiling and executing using exec in Java fails using command that works from the command line

So the idea is that this line in the code below
Runtime.getRuntime().exec("cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA");
should do the same thing as this line
cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA
when that second line is run from a terminal. That is to compile and run the java code. Am I misunderstanding how exec() works? If so, what would be the best way to go about accomplishing what it is I want to accomplish?
package PackA;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
public class classA {
public static void main(String[] args) throws Exception{
ClassLoader loader = classA.class.getClassLoader();
//Sets the file path to the path of the current .java file
File file = new File(loader.getResource(classA.class.getPackage().getName()+"/"+classA.class.getSimpleName()+".class").toString().replaceAll("file:", "").replaceAll("bin", "src").replaceAll("sA.class", "sA.java"));
BufferedReader in = new BufferedReader(new FileReader(file)); //establishes the reader that will be used to read this .java file
StringBuffer string = new StringBuffer(); //the stringBuffer that will be used to hold the contents of this .java file
String stringRead = in.readLine(); //sets a string to the first line of this .java file
while((stringRead) != null){ //as long as we haven't reached the end of the file
string.append(stringRead); //append the line
string.append(System.getProperty("line.separator")); //go to the next line
stringRead = in.readLine(); //read the next line
}
Integer intToFind = new Integer(0); //the integer being looked for
if (intToFind<=10) { //as long as the intToFind is less than or equal to 10
//increment the intToFind in the stringBuffer
StringBuffer newProgram = new StringBuffer(string.toString().replaceFirst("[(]"+intToFind.toString(), "("+String.valueOf(++intToFind)));
//establishes the writer that will be used to write to the file
BufferedWriter out = new BufferedWriter(new FileWriter(file));
out.write(newProgram.toString()); //write the newProgram to this .java file with the incremented intToFind
in.close(); //close both the reader and writer
out.close();
//Go to the directory of the java file, compile the code, move down one directory, execute the .class file
Runtime.getRuntime().exec("cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA");
}
}
}

cd is not a program, it's a shell command.
You could use ProcessBuilder instead, which would allow you to define the working directory context from which the command should be executed
Something like this for example
Abbriviated code from previous example, updated to provide the ability to specifiy the working directory
public int compile(String file, File workingDirectory) throws IOException, InterruptedException {
ProcessBuilder pb = new ProcessBuilder("javac", file);
pb.redirectError();
pb.directory(new File(workingDirectory));
Process p = pb.start();
InputStreamConsumer consumer = new InputStreamConsumer(p.getInputStream());
consumer.start();
int result = p.waitFor();
consumer.join();
System.out.println(consumer.getOutput());
return result;
}
public class InputStreamConsumer extends Thread {
private InputStream is;
private IOException exp;
private StringBuilder output;
public InputStreamConsumer(InputStream is) {
this.is = is;
}
#Override
public void run() {
int in = -1;
output = new StringBuilder(64);
try {
while ((in = is.read()) != -1) {
output.append((char) in);
}
} catch (IOException ex) {
ex.printStackTrace();
exp = ex;
}
}
public StringBuilder getOutput() {
return output;
}
public IOException getException() {
return exp;
}
}
Which you could call using something like...
compile("PackA/classA.java", new File("/Users/fnord/Documents/workspace/LearningJava/src"));
Now, if you're really courageous, you could take a look at How do you dynamically compile and load external java classes?, which uses javax.tools.JavaCompiler` class to compile a Java file...

Can you run a java class from within a java program?

I have been creating a program that writes and run java classes. So far I have been able to write a "Runable.java" class but not able to run it. I have tried to run a "runjava.bat" and get the .bat to run the "Runable.java" class but I keep getting a "Error: Could not find or load main class application.Runable.class". I was wondering what I am doing wrong or if there is a better way to go about running a java class from within a java program?
Here is my code(Simplify Slightly):
Main.java:
package application;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Platform;
import javafx.stage.FileChooser;
public class Main {
final static String Program =
"package application;\n"
+ "public class Runable {\n"
+ "public static void main(String[] args) {\n"
+ "System.out.println(\"Hello\");\n"
+ "}\n"
+ "}\n";
public static void main(String[] args) throws IOException {
Scanner s = new Scanner(System.in);
while(true){
System.out.println("State a comand.");
String Command = s.nextLine();
if (Command.equalsIgnoreCase("Write") || Command.equalsIgnoreCase("Save")){
FileChooser fileChooser = new FileChooser();
//Set extension filter
FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("TXT files (*.txt)", "*.txt");
fileChooser.getExtensionFilters().add(extFilter);
//Show save file dialog
File file = new File("src/application/Runable.class");
if(file != null){
SaveFile(Program, file);
}
}
else if (Command.equalsIgnoreCase("Run") || Command.equalsIgnoreCase("Play")){
ProcessBuilder builder = new ProcessBuilder(
"src/runjava.bat");
builder.redirectErrorStream(true);
Process p = builder.start();
BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while (true) {
line = r.readLine();
if (line == null) { break; }
System.out.println(line);
}
}
else if (Command.equalsIgnoreCase("End") || Command.equalsIgnoreCase("Exit")){
Platform.exit();
}
else{
System.err.println("Command not recognized.");
System.err.println("Please try again.");
}
}
}
private static void SaveFile(String content, File file){
try {
FileWriter fileWriter = null;
fileWriter = new FileWriter(file);
fileWriter.write(content);
fileWriter.close();
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
runjava.bat:
javac "src\application\Runable.java"
java application.Runable.class
and Runable.java if you didn't get it from the Main.java:
package application;
public class Runable {
public static void main(String[] args) {
System.out.println("Hello");
}
}

The java command expects a class name, not a filename. Unless your class is called "class" in the package "application.Runable" (which it isn't) you probably wanted to use:
java application.Runable

Because you can't execute a .java file like that. You must first compile it to get a .class file, and change the code that executes the class to point to Runable.class
The reason it is not running, is because the .java file is the code you type, and the .class file is the compiled version of the code that Java Virtual Machine executes.

Another solution to compile and run the program compared to executing the .bat file is to use the javax.tools API or another library based off of it. I have found InMemoryJavaCompiler library that makes it easy to compile and run the programs. This approach means that the program will run on the same JVM as your UI which may be helpful.
The following code shows how you might invoke the program using the library.
try{
Class<?> clazz = InMemoryJavaCompiler.compile("apllication.Runable", Program);
clazz.getMethod("main", String[].class).invoke(null, new String[0]);
}catch(Exception e){
e.printStackTrace();
}

In your Main.java's "Run" block, you should have
ProcessBuilder builder = new ProcessBuilder("runjava.bat");
In your runjava.bat, you should have (as immibis said)
javac -d . src/application/Runable.java
java application.Runable
** not Runable.class in the second line.
And runjava.bat should be placed in parallel with the parent folder of application\ but not the src\application folder. In other words, you should have something like classes\runjava.bat, classes\application\Main.class and classes\application\Runable.class. Hope it helps.

java restartApplication Method only restarts once?

I was trying to use a restartApplication method that I found on stack overflow, but for some reason it only will restart my application once. For example, in this simple JOptionPane program below, if the user enters the letter "a", it will restart the program. Once the program restarts, if the user types in "a" again, it just terminates the execution. How can I enable it to restart itself continuously?
I added in some println() statements to see if I could get any more info, and it just confirmed that the program is ending right after I type in the letter "a" on the second time around.
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.swing.JOptionPane;
public class JOptionTest{
public static void restartApplication()
{
final String javaBin = System.getProperty("java.home") + File.separator + "bin" + File.separator + "java";
final File currentJar = new File("C:\\Documents and Settings\\My Documents\\hello3.jar");//UpdateReportElements.class.getProtectionDomain().getCodeSource().getLocation().toURI());
/* is it a jar file? */
if(!currentJar.getName().endsWith(".jar"))
return;
/* Build command: java -jar application.jar */
final ArrayList<String> command = new ArrayList<String>();
command.add(javaBin);
command.add("-jar");
command.add(currentJar.getPath());
final ProcessBuilder builder = new ProcessBuilder(command);
try {
builder.start();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.exit(0);
}
public static void main(String[] args){
String str = JOptionPane.showInputDialog(null, "Enter some text",1);
System.out.println(str);
//String a= "a";
if (str.equals("a")){
System.out.println(str+ "right about to restart");
restartApplication();
}
}
}

See this line?
System.exit(0);
you are calling restartApplication a Single time and when it ends you exit the java process.
If you want to restart continuously, then remove this line and probably iterate forever:
public static void restartApplication()
{
while(true){
final String javaBin = System.getProperty("java.home") + File.separator + "bin" + File.separator + "java";
final File currentJar = new File("C:\\Documents and Settings\\XBBKKYL\\My Documents\\hello3.jar");//UpdateReportElements.class.getProtectionDomain().getCodeSource().get Location().toURI());
/* is it a jar file? */
if(!currentJar.getName().endsWith(".jar"))
return;
/* Build command: java -jar application.jar */
final ArrayList<String> command = new ArrayList<String>();
command.add(javaBin);
command.add("-jar");
command.add(currentJar.getPath());
final ProcessBuilder builder = new ProcessBuilder(command);
try {
builder.start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I have not tested this, it's just an idea