Compiling and Running Java program by using another Java program.

package com.ranga;

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

/**
  Program: Compiling and Running Java program by using another Java program.
  java.lang.Runtime.exec()
*/

public class Main {
  public static void main(String[] args) {
    System.out.println("I am in Main class begin.");
    Process process = null;
    try {
      process = Runtime.getRuntime().exec("javac Test.java");
      System.out.println("Test class successfully compiled.");
    } catch (IOException ex) {
      ex.printStackTrace();
    } catch (Exception ex) {
      ex.printStackTrace();
    }

    try {
      process = Runtime.getRuntime().exec("java Test");
      printMessage(" stdout:", process.getInputStream());
      System.out.println("Test class successfully runned.");
    } catch (IOException ex) {
      ex.printStackTrace();
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
    System.out.println("I am in Main class end.");
  } // end main()

  private static void printMessage(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);
    }
  } // end printMessage()
} // end Main class

class Test {
  public static void main(String a[]) {
     System.out.println("I am in Test class");
  }
}