Tempo de execução de um programa externo - a revolta das threads

Executa execu = new Executa();
		//long inicioTempoMs = System.currentTimeMillis();		
		int exe = execu.executa("c:/windows/notepad.exe", "Felipe", "123");
		execu.executa("C:/WINDOWS/system32/calc.exe", "Felipe", "123");

package com.tcc;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.sql.SQLException;

public class Executa {
	
	public Executa () throws IOException, InterruptedException {
		super();
	}	
	
	public int executa(final String caminhoPrograma, String usuario, String senha) throws IOException, InterruptedException, InstantiationException, IllegalAccessException, ClassNotFoundException, SQLException{
		
		final Process p = Runtime.getRuntime().exec(caminhoPrograma);
		
		final Monitora monit = new Monitora(usuario, senha);	
		monit.setDescricao(caminhoPrograma);
		
		// ARMAZENA O INICIO DA EXECUCAO DO PROGRAMA
		long inicioTempoMs = System.currentTimeMillis();
		
		new Thread(){
			public void run(){
				try{
					long inicio = System.currentTimeMillis();
					p.waitFor();
//IMPRIME O TEMPO Q LEVOU PARA EXECUTAR
					System.out.println(System.currentTimeMillis() - inicio);
				}catch (InterruptedException e) {
					e.printStackTrace();
				}
		    }
		}.start(); 		
		
		new Thread(){
			public void run(){
				try{
					BufferedReader in = new BufferedReader(new InputStreamReader (p.getInputStream()));
					  String str = null;
					  while ( (str = in.readLine()) != null )
						  System.out.println(str);
					  monit.setSaida(str);
					  in.close();
				}catch (IOException e){
					e.printStackTrace();
				}
		    }
		}.start();    
		
		new Thread(){
			public void run(){
				try{
					BufferedReader in = new BufferedReader(new InputStreamReader (p.getErrorStream()));
					  String str = null;
					  while ( (str = in.readLine()) != null )
					    System.out.println(str);
					  monit.setErro(str);
					  in.close();					
				}catch (IOException e){
					e.printStackTrace();
				}
		    }
			
		}.start();
		
		// GRAVA O TEMPO EM QUE O PROGRAMA FICOU EM EXECUCAO
		Long terminoTempoMs = new Long(System.currentTimeMillis() - inicioTempoMs);		
		monit.setTempo(terminoTempoMs.toString());
		monit.gravar();	
	
		return 0;
	
	} 	
}