Running java program from another java program

Question

I'm trying to run a Java program from another Java application. Here is my code:

public class Main {
  public static int Exec() throws IOException {
    Process p = Runtime.getRuntime().exec("javac -d C:/Users/Dinara/Desktop/D/bin "
            + "C:/Users/Dinara/Desktop/D/src/test.java");
    Process p1 = Runtime.getRuntime().exec("java -classpath C:/Users/Dinara/Desktop/D/bin test");
    return 0;
  }

  public static void main(String[] args) throws IOException {
    Exec();
  }
}

javac works fine and creates test.class file in bin directory. However java -classpath C:/Users/Dinara/Desktop/D/bin test does not run the test.class file. the content of the test.java:

import java.io.*;
class test {
  public static void main(String args[]) {
    try {  
      FileWriter fstream = new FileWriter("out.txt");
      BufferedWriter out = new BufferedWriter(fstream);
      out.write("Hello Java");
      out.close();
    } catch (Exception e) {
    System.err.println("Error: " + e.getMessage());
    }
  }
}

I suppose that something wrong with recognizing Java command. Could you please give me a sample code for fixing this problem or share idea? I'm using Netbeans to run Main class and the location of the application folder is C:\Users\Dinara\Main

Ilya · Accepted Answer · 2012-08-02 10:51:17Z

3

Use

System.getProperty("java.home") + "/bin/java -classpath C:/Users/Dinara/Desktop/D/bin test"

instead of

"java -classpath C:/Users/Dinara/Desktop/D/bin test"

edited Aug 2, 2012 at 10:51

answered Aug 2, 2012 at 10:42

Ilya

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3 Comments

Dinara Over a year ago

I did use your example, but still I can not get out.txt file with result;(

Ilya Over a year ago

Where do you search output file out.txt?

Ilya Over a year ago

I run programm, and file is created. In directory, where from I start class Main

MadProgrammer · Accepted Answer · 2012-08-02 10:39:04Z

2

You need to supply the full path to the javac, exec won't use the ath to find it for you

answered Aug 2, 2012 at 10:39

MadProgrammer

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3 Comments

Dinara Over a year ago

What exactly you by full path? I was thinking that I supplied a full path in both cases for javac and java. I'm newer and if i did understand you in wrong way -sorry

MadProgrammer Over a year ago

Full path to the javac ie C:\Progam Files\Java\JDK\bin\javac, or use llya example ;)

Dinara Over a year ago

The thing is that javac works ok and creates test.class file. The problem is java. But I did wrote the full path to javac. Still can not get test.class runned

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