title: how to catch internet error when its not available
body: <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>