About runtime.exec("passwd")

Question

In solaris,you can use command "passwd" to change password of user.
Now i want to use the command in java.But i can not get the result like below:
%new password:(type the password)
Re-type password:
my codes is copied here,please help me .
import java.util.Enumeration;
import java.io.*;
import java.lang.*;
public class liu{
     public static void main(String args[]) throws Exception{
          try{
               Runtime rr=Runtime.getRuntime();
               String[] aaa={ "passwd"};//passwd liuyang"};//ls -l"};
               Process cess=rr.exec(aaa);
          String sss;
               DataOutputStream out=new DataOutputStream(new BufferedOutputStream(cess.getOutputStream()));
//               out.writeBytes("qwerty\n");
               out.writeBytes("OUTPUT");
               out.flush();
               DataInputStream in=new DataInputStream(cess.getInputStream());
               while((sss=in.readLine())!=null)
                    System.out.println(sss);
          }catch (Exception ex) {
               System.out.println("Exception:"+ex);

Answer 1

I would really recommend not to code your own password utility in java. Yours will be insecure and will echo onto the screen whilst the default unix one will be as secure as sun can make it.
Jon