How to execute shell command from Java

  p = Runtime.getRuntime().exec("host -t a " + domain);
  p.waitFor();
 
  BufferedReader reader = 
     new BufferedReader(new InputStreamReader(
	 p.getInputStream()));
  String line = reader.readLine();
  while (line != null) {
	line = reader.readLine();
  }

package com.mkyong;
 
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class ExecuteShellComand {
 
	private static final String IPADDRESS_PATTERN = "([01]?\\d\\d?|2[0-4]\\d|25[0-5])"
			+ "\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])"
			+ "\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])"
			+ "\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])";
 
	private static Pattern pattern = Pattern.compile(IPADDRESS_PATTERN);
	private static Matcher matcher;
 
	public static void main(String[] args) {
 
		String domain = "google.com";
 
		Process p;
		try {
			p = Runtime.getRuntime().exec("host -t a " + domain);
			p.waitFor();
			BufferedReader reader = new BufferedReader(new InputStreamReader(
					p.getInputStream()));
 
			StringBuffer sb = new StringBuffer();
 
			String line = reader.readLine();
			sb.append(line);
			while (line != null) {
				line = reader.readLine();
				sb.append(line);
			}
 
			List<String> list = getIpAddress(sb.toString());
 
			if (list.size() > 0) {
				System.out.println(domain + " has address : ");
				for (String ip : list) {
					System.out.println(ip);
				}
			} else {
				System.out.println(domain + " has NO address.");
			}
 
		} catch (Exception e) {
			e.printStackTrace();
		}
 
	}
 
	public static List<String> getIpAddress(String msg) {
 
		List<String> ipList = new ArrayList<String>();
 
		if (msg == null || msg.equals(""))
			return ipList;
 
		matcher = pattern.matcher(msg);
		while (matcher.find()) {
			ipList.add(matcher.group(0));
		}
 
		return ipList;
	}
}

google.com has address : 
74.125.135.139
74.125.135.100
74.125.135.101
74.125.135.102
74.125.135.113
74.125.135.138