我正在学习java进程，我正在尝试创建两个在同一进程中运行的同一java类示例，这是一个要求。

class Chat {
    public void getMessage() { * * * some implementation
    }
}

class ProcessMain {
     public static void main(String args[]) {
         Chat c1 = new Chat();
         Chat c2 = new Chat();
         ProcessBuilder pb = new ProcessBuilder(c1); * * * * here is where I am stuck.
         Two instances of same class should run in same process
     }
 }

谁能给我个线索吗？