Develop Reference

Execute the command julia.exe in Java

I'm trying to execute julia.exe in Java.
Here is the code:
Process pTest = Runtime.getRuntime().exec("C:/Program Files/Julia-0.4.1/bin/julia.exe");
When I run it, nothing happens.
However, if I try another executable file, it works well. For example:
Process pTest = Runtime.getRuntime().exec("C:/Program Files/anotherProgram/program.exe");
program.exe will run just as expected.
julia.exe is a little special.
If I run it on command prompt, it will execute on the command prompt. In other words, it won't pop up its own window.
I've done a test:
#julia script, it's path: C:/Users/Thomas/Julia/test.jl
function test1()
println("it's test1")
end
test1()
I execute this command on the command prompt:
C:\>C:/Program Files/Julia-0.4.1/bin/julia.exe C:/Users/Thomas/Julia/test.jl
then I will get it's test1 on the command prompt.
What I need is to execute C:/Program Files/Julia-0.4.1/bin/julia.exe C:/Users/Thomas/Julia/test.jl in my java project and get it's test1 on the console of eclipse.
Here is my java project:
public class Main {
public static void main(String[] args){
try {
String[] params = {"C:/Program Files/Julia-0.4.1/bin/julia.exe", "C:/Users/Thomas/Julia/test.jl"};
Process pTest = Runtime.getRuntime().exec(params);
try {
if (pTest.waitFor() != 0) {
System.err.println("exit value = " + pTest.exitValue());
}
BufferedReader in = new BufferedReader(new InputStreamReader(pTest.getInputStream()));
StringBuffer stringBuffer = new StringBuffer();
String line = null;
while ((line = in.readLine()) != null) {
stringBuffer.append(line+"-");
}
System.out.println(stringBuffer.toString());
} catch (InterruptedException e) {
System.err.println(e);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

Consider this changed (and working) implementation removing the too-early invocation of waitFor and exitValue:
public class Main {
public static void main(String[] args) {
try {
String[] params = {"C:/Program Files/Julia-0.4.1/bin/julia.exe",
"C:/Users/Thomas/Julia/test.jl"};
Process pTest = Runtime.getRuntime().exec(params);
BufferedReader in = new BufferedReader(new InputStreamReader(pTest.getInputStream()));
String line = null;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
System.out.println("===");
System.out.println("Julia exit value = " + pTest.exitValue());
} catch (IOException e) {
e.printStackTrace();
}
}
}
This produced the following output with your test-script:
it's test1
===
Julia exit value = 0

I got it finally.
As julia.exe execute on the command prompt immediately, we must give admin privileges to the users of cmd.exe.

Programatically interact with an I/O program in Java

I am writing a program that utilizes a third party mathematics software, "Maxima". This program is a command line interface, and so it can communicate through my Java program with simple I/O routing. I have already figured out how to run the program from within Java, and I have read a lot about how I can reconfigure System.out and how InputStreams/OutputStreams work, but I can't figure out how to do the following (what I think should be a pretty simple task):
Output to Maxima a command from Java, (like the string "5 + 5;")
Retrieve Maxima's output, and deal with it from Java code (like maybe printing the given string + "blah").
Output another command to Maxima from Java...
etc.
-
Below is code which will run Maxima and allow me to interact with it on the Eclipse Console
public static void main(final String[] args) {
// An idea I had for manipulaing how the printstream works.
// Set the system.out to be a custom Prinstream.
// final PrintStream interceptor = new Interceptor(origOut);
// System.setOut(interceptor);
// Run the program:
final String programLocation = "\"C:\\Program Files (x86)\\Maxima-sbcl-5.37.2\\bin\\maxima.bat\"";
final ProcessBuilder pb = new ProcessBuilder();
pb.redirectInput(Redirect.INHERIT); // Inherit I/O
pb.redirectOutput(Redirect.INHERIT);
pb.command(programLocation);
try {
// Start the program and allow it to run in Eclipse's/the program's
// console.
pb.start().waitFor();
} catch (final InterruptedException e) {
e.printStackTrace();
} catch (final IOException e) {
e.printStackTrace();
}
}
This allows for the following style of interaction:

Thanks to the words of wisdom from #RealSkeptic, I think I worked out a solution here.
The key was building a BufferedWriter, and a BufferedReader to interact with the I/O of Maxima. That is:
BufferedWriter w = new BufferedWriter(new OutputStreamWriter(process.getOutputStream()));
BufferedReader r = new BufferedReader(new InputStreamReader(process.getInputStream()));
Those two lines of code create buffered readers and writers which can input data to Maxima, and read what Maxima output. Here is a (fairly lengthy) use case of this method, which I use to do basically what I asked in the question:
public class TestClass {
public static void main(final String[] args) {
#SuppressWarnings("unused")
final TestClass ts = new TestClass();
}
private BufferedWriter w;
private BufferedReader r;
public TestClass() {
// Start the process using process builder
final String programLocation = "\"C:\\Program Files (x86)\\Maxima-sbcl-5.37.2\\bin\\maxima.bat\"";
final ProcessBuilder pb = new ProcessBuilder();
pb.command(programLocation);
Process process;
try {
process = pb.start();
} catch (final IOException e) {
e.printStackTrace();
process = null;
// killProgram();
}
// Build your own wrappers for communicating with the program.
w = new BufferedWriter(
new OutputStreamWriter(process.getOutputStream()));
r = new BufferedReader(new InputStreamReader(process.getInputStream()));
// Print the five starting messages.
printFromBuffer();
printFromBuffer();
printFromBuffer();
printFromBuffer();
printFromBuffer();
// Run the following three commands in Maxima
runCommand("5+5;");
runCommand("2*65;");
runCommand("quit();");
}
/**
* Runs the given string and prints out the returned answer.
*/
private void runCommand(final String s) {
try {
w.write(s);
w.flush();
printFromBuffer();
printFromBuffer();
} catch (final IOException e) {
e.printStackTrace();
}
}
private void printFromBuffer() {
try {
final String s = r.readLine();
System.out.println(s + " -blah");
} catch (final IOException e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
}
}

getRuntime().exec() does nothing

I want a java program to execute the following shell command:
apktool.jar d /path/to/my/app.apk
This command perfectly works when executing it directly on command line.
Java Code:
public static void main(String[] args) {
String command = "apktool d /path/to/my/app.apk";
try {
Runtime.getRuntime().exec(command);
} catch (IOException e1) {
e1.printStackTrace();
}
}
There is no error, no exception. Nothing happens and i have the impression that I already searched the entire internet for a solution. Does anybody know what I am doing wrong? A simple command like
mkdir /path/to/a/new/folder
works without problems.
I tried the same using ProcessBuilder:
try {
Process process = new ProcessBuilder(command).start();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
This time i only get "Cannot run program "apktool d /path/to/my/app.apk, No such file or directory". I can't even run the mkdir command.

You need to call the jar with java.exe, and you're not doing that. Also you need to trap the input and error streams from the process, something you can't do the way you're running this. Use ProcessBuilder instead, get your streams and then run the process.
For example (and I can only do a Windows example),
import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;
public class ProcessEg {
private static Process p;
public static void main(String[] args) {
String[] commands = {"cmd", "/c", "dir"};
ProcessBuilder pBuilder = new ProcessBuilder(commands);
pBuilder.redirectErrorStream();
try {
p = pBuilder.start();
InputStream in = p.getInputStream();
final Scanner scanner = new Scanner(in);
new Thread(new Runnable() {
public void run() {
while (scanner.hasNextLine()) {
System.out.println(scanner.nextLine());
}
scanner.close();
}
}).start();
} catch (IOException e) {
e.printStackTrace();
}
try {
int result = p.waitFor();
p.destroy();
System.out.println("exit result: " + result);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}

Try doing it like this:
StringBuffer output = new StringBuffer();
Process p;
try {
p = Runtime.getRuntime().exec("./path/apktool d /path/to/my/app.apk");
p.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";
while ((line = reader.readLine())!= null) {
output.append(line + "\n");
}
} catch (Exception e) {
e.printStackTrace();
}
system.out.println(output.toString());
Creating first a process allows you to wait for a response and reads the output of the execution of your process.
If something is failing while running your shell command, you will have the error printed at the end.
Also, make sure your java program can access your shell script, or better provide the full path to it like:
./path/to/shell/apktool d /path/to/my/app.apk

Is is possible to direct windows console output to a GUI?

I'm working on a project and I would like to execute programs in the windows console or a linux terminal.
Instead of launching a new console and working the program in it I want to do something like the following:
rt.exec("cmd.exe /c start cmd.exe /k ruby rubycode.rb");
From this point on I want the user to be able to work with the program from the GUI/my program. The idea in my min is starting cmd in silent mode where it is not visible and latching on to it. Then redirecting the console output to the GUI and letting the user input data to the console through the GUI.
A similar concept is what most IDEs like jgrasp do. When you run a program you interface with it though their own command prompt.
How is this done? Iv'e tried grabbing the IOStreams from the process and trying to atleast print what the console outputs but no luck.

Here is an example:
public class ProcessTest {
private Process p;
private BufferedReader reader;
private BufferedWriter writer;
public void start() throws IOException {
ProcessBuilder pb = new ProcessBuilder("cmd", "/c", "dir");
pb.directory(new File("./"));
this.p = pb.start();
this.reader = new BufferedReader(new InputStreamReader(this.p.getInputStream()));
this.writer = new BufferedWriter(new OutputStreamWriter(this.p.getOutputStream()));
new Read(this.reader).start();
}
public boolean writeToConsole(String s) throws IOException {
if (p == null)
return false;
this.writer.write(s + "\n");
this.writer.flush();
return true;
}
public class Read extends Thread {
private BufferedReader reader;
public Read(BufferedReader reader) {
this.reader = reader;
}
public void run() {
try {
String line;
while ((line = this.reader.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try {
new ProcessTest().start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
With the writeToConsole method you can write any string to the programm that you executed.

run a java file within another java file and display its output to console

i have a hello world class hworld.class which displays "Hello World" on the console. i am trying to run it from another class in console using the code
public class ftest2
{
public static void main(String[] arg)
{
System.out.println("NEW FILE PRINT LINE EXECUTED");
try {
Process pro1 = Runtime.getRuntime().exec("javac hworld.java");
pro1.waitFor();
Process pro2 = Runtime.getRuntime().exec("java hworld");
pro2.waitFor();
} catch (Exception e) {
System.out.println("Some Error");
e.printStackTrace();
}
} }
but when the file is executed, the output of Hello World is not displayed on the console.
the program just starts and displays
NEW FILE PRINT LINE EXECUTED
insted of
NEW FILE PRINT LINE EXECUTED
HELLO WORLD
how it would be possible to display the output of HELLO WORLD as well.
(it is example program. i want to display the output of a program within another program)
if there is another way to call a class within another class to display its output. then please mention it.

You need to read in the InputStream of the process, which is
The stream obtains data piped from the standard output stream of the
process represented by this Process object.
Source: http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Process.html#getInputStream()
Read InputStream and write out to System.out:
InputStream inputStream = process.getInputStream();
int b = -1;
while ( (b = inputStream.read()) != -1 ) {
System.out.write(b);
}

You need to redirect the inputstream of your process to System.out, for example:
public static void main(String[] arg) {
System.out.println("NEW FILE PRINT LINE EXECUTED");
try {
Process pro1 = Runtime.getRuntime().exec("javac hworld.java");
try (BufferedReader reader = new BufferedReader(new InputStreamReader(pro1.getInputStream(), Charset.forName("UTF-8")))) {
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
Note: it uses the try with resources syntax of Java 7 but is easily transposable to Java 6- if necessary.

Might be you are getting exception and you've not printed it.
public class ftest2
{
public static void main(String[] arg)
{
System.out.println("NEW FILE PRINT LINE EXECUTED");
try {
Process pro1 = Runtime.getRuntime().exec("javac hworld.java");
pro1.waitFor();
Process pro2 = Runtime.getRuntime().exec("java hworld");
pro2.waitFor();
} catch (Exception e) {
System.out.println("Some Error");
e.printStackTrace();
}
}
}
and another way
public static void main(String[] arg)
{
System.out.println("NEW FILE PRINT LINE EXECUTED");
hworld.main(arg); // since main is a static method can be called w/o instance
}