how to execute cmd command using another program in java

Question

I want to make a program that open another java programs.how can i run/execute the cmd command in compiling and running java programs.

for example c:\Users\Burnok> javac HelloWorld.java and c:\Users\Burnok> java HelloWorld

how can i do that inside the java program? please help.

I tried this code but it compiled successfully but if i tried to run the HelloWorld.class it says that the could not find or load main class.

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

import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;


public class Test {

     private static void printLines(String name, InputStream ins) throws Exception {
            String line = null;
            BufferedReader in = new BufferedReader(
                new InputStreamReader(ins));
            while ((line = in.readLine()) != null) {
                System.out.println(name + " " + line);
            }
          }

      private static void runProcess(String command) throws Exception {
        Process pro = Runtime.getRuntime().exec(command);
        printLines(command + " stdout:", pro.getInputStream());
        printLines(command + " stderr:", pro.getErrorStream());
        pro.waitFor();
      }

      public static void main(String[] args) {
        try {
            runProcess("javac src/HelloWorld.java");
            runProcess("java src/HelloWorld");
        } catch (Exception e) {
          e.printStackTrace();
        }
      }

}

here is the error java src/HelloWorld stderr: Error: Could not find or load main class src.HelloWorld

Check this http://stackoverflow.com/questions/4842684/how-to-compile-run-java-program-in-another-java-program — sujithvm, Aug 01 '14 at 13:50
i try that but if i tried to run the .class it says that could not find or load main class. — user3276091, Aug 01 '14 at 13:53
see http://www.mkyong.com/java/how-to-execute-shell-command-from-java/ — La-comadreja, Aug 01 '14 at 14:02
Have you checked where HelloWorld.class gets generated and where the current context is when you execute? Is is possible the class file is inside the src directory? — JustinKSU, Aug 01 '14 at 14:07

score 1 · Accepted Answer · edited May 23 '17 at 10:33

1

Your are supposed to mention class path while running from another directory

syntax is java -classpath directory_to_program Program

try {
        runProcess("javac src/HelloWorld.java");
        runProcess("java -classpath src HelloWorld");
    } catch (Exception e) {
      e.printStackTrace();
    }

Read for more info How do I run a java program from a different directory?

edited May 23 '17 at 10:33

Community

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answered Aug 01 '14 at 14:08

sujithvm

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Thanks it display hello world but i want to run just like the Test class that open another cmd – user3276091 Aug 01 '14 at 14:11
@user3276091 sorry can you explain 'that open another cmd' ? – sujithvm Aug 01 '14 at 14:13
@user3276091 sujithvm just fixed the bug, not introduced the new way to run, what's the problem then? – Dmitry Ginzburg Aug 01 '14 at 14:16
yeah but sorry but i want to open another cmd that display helloWorld – user3276091 Aug 01 '14 at 14:17
@user3276091 Do you another **window** with command line to be opened? – Dmitry Ginzburg Aug 01 '14 at 14:21
yes.can you please teach me. because i want to make a program that will open a java GUI window using that Test class. – user3276091 Aug 01 '14 at 14:24
In Windows, put "start" in front of the command. "start java -classpath src HelloWorld" – JustinKSU Aug 01 '14 at 20:35

how to execute cmd command using another program in java

1 Answers1