Using exec() to run a class

[alexteslin]

Hi,
I would like to run a class file from my application. I managed to compile the java file, but got stack with executing it. To be more clear, i will post my code here:

    public static void main(String args[]) throws Exception
    {
        try {
            String line;
            Runtime rt = Runtime.getRuntime();
            String[] cmd = { 
                "c:/progra~1/Java/jdk1.5.0_05/bin/javac.exe", "c:/Temp/Test1/MainTest.java"};    
            Process p = rt.exec(cmd);
            int exitVal = p.waitFor();
            System.out.println("After compilation value: " + exitVal);
            
            String[] cmd2 = {
                "cmd.exe", "/c","c:/progra~1/Java/jdk1.5.0_05/bin/java.exe -cp MainTest"};
            Runtime rt2 = Runtime.getRuntime();
            p = rt2.exec(cmd2);
                        
            BufferedReader input = new BufferedReader(new InputStreamReader(p.getErrorStream()));
            String temp = "";
            while((temp = input.readLine()) != null) {
                System.out.println(temp);
            }
            input.close();
            }
         catch(IOException e) {
            System.err.println("Error on exec() method");
            e.printStackTrace();
        }
    }

After compilation the exit value is 0 and creates a class file. But when i try to run it is either jumps to an exception and prints errors or prints the error from a BufferedReader:
java.lang.NoClassDefFoundError: c:/Tem/Test1/MainTest
Exception in thread "main"

I have tried several way for cmd2 commands but just would not run.
Any help would be much appriciated.

[jorgo]

I think you are missing the classpath to the newly generated .class file.

try changing cmd2 to

String[] cmd2 = {
"c:/progra~1/Java/jdk1.5.0_05/bin/java.exe",
"-cp",
"c:/Temp/Test1",
"MainTest" };

[aniseed]

A simpler method is to include the tools.jar from the JDK distribution in the CLASSPATH and use the com.sun.tools.javac.Main class. Refer to Java Tip: Make a statement with javac!