외부 실행화일 자바 Tread로 돌리는 방법

import java.io.*;

public class runThread implements Runnable{
 protected Runtime rt;
 protected String cmd;
 static int nSuc=0;
 public runThread(){
  rt=Runtime.getRuntime();
  cmd="java Test";
  
 }
 public void run(){
  try{
   Process proc=rt.exec(cmd);
   InputStream in=proc.getInputStream();
   byte buffer[]=new byte[12000];
   int n=-1;   
   String Temp = "";
   
   ;
   //System.out.println(n);
   
   while ( (n=in.read(buffer)) != -1 || (n=in.read(buffer)) !=0 ) {
    //System.out.println(n);
    if (n<=0) break;
    Temp=new String(buffer,0,n);
    
    if ( Temp == null ) {
     return ;
    }
    
    if ( Temp.indexOf("성공")>=0 ) {
     nSuc++;
     System.out.print(Temp);
     System.out.println(String.valueOf(nSuc) + "/50");
    }
    //n=in.read(buffer);
   }
   in.close();
   return ;
  }catch(Exception ex){
   ex.printStackTrace();
  }
 }
 public static void main(String[]args){
  for(int i = 0; i < 20; i++){
   Thread t = new Thread(new runThread());
   t.start();
  }
 }
}