Answers for "java run cmd"

cmd java compile

javac MyFisrtProgam.java // enter to compile 
  java MyfirstProgram // run program

java run cmd

public void excCommand(String new_dir){
    Runtime rt = Runtime.getRuntime();
    try {
        rt.exec(new String[]{"cmd.exe","/c","start"});

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

run java in cmd

C:\Users\Your Name>javac MyClass.java