title: Android app doesn't work on Android 4
body: <p>I created an Android project on 2.3.3 and tried it on mobile 2.3.3, everything works OK. It didn't work on mobile 4, so I re-built for Android 4, but I have the same problem.</p>
  
  <p>This is the code:</p>
  
  <pre><code>public void FTP_Download(){
    String server = "192.168.1.135";
    int port = 21;
    String user = "pc1";
    String pass = "1551";
    FTPClient ftpClient = new FTPClient();
    try {
      ftpClient.connect(server, port);
      ftpClient.login(user, pass);
      ftpClient.enterLocalPassiveMode();
      ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
      Toast.makeText(getBaseContext(), "download starting.",Toast.LENGTH_LONG).show();
      // APPROACH #1: using retrieveFile(String, OutputStream)
      String remoteFile1 = "i.xml";
      File downloadFile1 = new File("sdcard/i.xml");
      OutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(downloadFile1));
      boolean success = ftpClient.retrieveFile(remoteFile1, outputStream1);
      outputStream1.close();
      if (success) {
        Toast.makeText(getBaseContext(), "File #1 has been downloaded successfully.",Toast.LENGTH_LONG).show();
      }
    } catch (IOException ex) {
      System.out.println("Error: " + ex.getMessage());
      ex.printStackTrace();
    } finally {
      try {
        if (ftpClient.isConnected()) {
          ftpClient.logout();
          ftpClient.disconnect();
        }
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
  }
  </code></pre>
  
  <p>Note:</p>
  
  <p>I use commons-net-3.1 to connect.</p>