Java Runtime.exec() hangs

public static void main(String[] args) {

try {

Process process = Runtime.getRuntime().exec(
"E:\\test\\dbbackup.cmd");

new MyThread(process.getErrorStream()).start();

new MyThread(process.getInputStream()).start();

int status = process.waitFor();

if (status == 0) {

System.out.println("exit success");

} else {

System.out.println("exit fail");
}

} catch (Exception e) {

System.out.println("exception occurs......");

e.printStackTrace();
}
}

public class MyThread extends Thread{
BufferedReader bf;

public MyThread(InputStream input){
bf=new BufferedReader(new InputStreamReader(input));
}
public void run(){
String line;
try {
line = bf.readLine();
while(line!=null){
System.out.println(line);
line=bf.readLine();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}