how to catch internet error when its not available
<p>hello sir in login page i am validating username and password from server database. if net is there means my application is working properly. if i disconnect internet means my application run means it show error application was not responding. how to eliminate this type of error </p>

<pre><code>    i try this code
        if(name.equals("") || pass.equals(""))
            {
                 Toast.makeText(Main.this, "Please Enter Username and Password", Toast.LENGTH_LONG).show();
            }
            else
            {

            try {
                httpclient = new DefaultHttpClient();
                httppost = new HttpPost("server url/login.php");
                // Add your data
                nameValuePairs = new ArrayList&lt;NameValuePair&gt;(2);
               nameValuePairs.add(new BasicNameValuePair("UserEmail", name.trim()));
                nameValuePairs.add(new BasicNameValuePair("Password", pass.trim()));
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

                // Execute HTTP Post Request
                response = httpclient.execute(httppost);
                inputStream = response.getEntity().getContent();

                data = new byte[256];

                buffer = new StringBuffer();
                int len = 0;
                while (-1 != (len = inputStream.read(data)) )
                {
                    buffer.append(new String(data, 0, len));
                }

                inputStream.close();
            }

            catch (IOException e) {
                 System.out.println(e);

                 //alertDialog.cancel();

            }
            if(buffer.charAt(0)=='Y')
            {

                Intent intent=new Intent(getApplicationContext(),ManagerHandset.class);
                startActivity(intent);
            }
            else
            {
                Toast.makeText(Main.this, "Invalid Username or password", Toast.LENGTH_LONG).show();
            }
            }
        }
    });
</code></pre>

<p>if i want disconnect my net means how to show alert net is not available </p>
