use cmd commands in java program

Question

i need a java program in java that compiles other java programs using cmd commands

Answer 1

Runtime.exec( -whatever cmd command you need to execute- )

http://download.oracle.com/javase/6/docs/api/java/lang/Runtime.html

Vinod.

Answer 2

Maybe you are looking for Java Runtime.exec() function:

exec
public Process exec(String command)
              throws IOException

Executes the specified string command in a separate process. This is a convenience method. An invocation of the form exec(command) behaves in exactly the same way as the invocation exec(command, null, null).

Answer 3

To execute real cmd commands you need to start cmd.exe with the /c option using Runtime.exec or a ProcessBuilder like

    String cmd = "dir > t.txt";
    ProcessBuilder builder = new ProcessBuilder("cmd.exe", "/c", cmd);
    Process process = builder.start();
    process.waitFor();
    System.out.println("done");

To start an executable like calc.exe you can start it directly

    ProcessBuilder builder = new ProcessBuilder("calc.exe");
    Process process = builder.start();
    process.waitFor();
    System.out.println("done");

^{both code samples missing IO and Exception handling...}

Answer 4

Additional note:

If using JDK1.6 you can now programmatically compile from another java program using JavaCompiler. You could invoke your compiler program from the command line if this is what you are trying to achieve.

Answer 5

Not sure why you'd want to explicitly invoke the shell in order to compile Java programs. if you're absolutely sure that this is what you need to do, then go for it and follow the suggestions given by the others. However, if all you want to do is to compile Java code from within a Java program, you can do that with Java 6.0 (and up):

http://docs.oracle.com/javase/6/docs/api/javax/tools/JavaCompiler.html

Answer 6

using the cmd could be done like this:

String cmd = "c:\\Programme\\Ghostgum\\gsview\\gsprint.exe"; //what to execute
String prt = "-printer XYZ"; // additional parameters
String dat = "\"" + pfad + "\""; // the file to be passed
ProcessBuilder pb = new ProcessBuilder(cmd, prt, dat);
System.out.println(cmd + " " + prt + " " + dat);
pb.redirectErrorStream(true);
Process ps = pb.start();
ps.waitFor();

Answer 7

I finally got my answer. It actually compiles a Java program. The program is as follows:

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Dos {
    public static void main(String[] args) {
        try {
            String[] command = new String[4];
            command[0] = "cmd";
            command[1] = "/C";
            command[2] = "C:/Program Files/Java/jdk1.6.0_21/bin/javac";//path of the compiler
            command[3] = "d:\\a.java";

            Process p = Runtime.getRuntime().exec(command);

            BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));

            BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));

            // read the output from the command

            String s = null;
            System.out.println("Here is the standard output of the command:\n");
            while ((s = stdInput.readLine()) != null) {
                System.out.println(s);
            }

            // read any errors from the attempted command

            System.out.println("Here is the standard error of the command (if any):\n");
            while ((s = stdError.readLine()) != null) {
                System.out.println(s);
            }
            System.out.println("I am In try");
        }

        catch (Exception e) {
            System.out.println("I am In catch");
        }
    }
}