Android Introduction

1
Android Introduction

• Hello Socket Programming
• TCP and UDP

2
Goal

• Convert the Java Socket Programming Project to
  Android

Text input from the user sent to the same
server(s) as before
Answer from the server(s)
Sends the input from the user to the UPD Server
Sends the input from the user to the TCP Server
3
Layout

• Create a simple layout that will include the
  required elements
• EditText
• TextView
• Buttons
• Register one OnClickedListener() for each of
  the buttons
• Test functionality (make a toast for each
  listener)

4
Socket Programming

• Define most variables as members of the main
  Activity Class
• Rename
• DatagramSocket clientSocket -gt DatagramSocket
  udpClientSocket
• Socket clientSocket -gt Socket tcpSocket
• Adapt the code from pure Java to Android
  (especially the input and output strings) by
  filling in the two OnClickListeners

5
Handling Exceptions

• Many network operations throw exceptions (as they
  can fail). In the original code they were just
  thrown out of main in Android we have to handle
  them!
• Try
• Operations that may fail and throw an exception
• catch (Exception e)
• Log.e(TAG,"Caught UDP Exception
  e.getMessage())
• Toast.makeText(HelloNets.this, "UDP Error"
  e.getMessage()), Toast.LENGTH_LONG).show()

6
Running it

• First give the application INTERNET permissions
  (like in the WebView)
• Implement the UDP and TCP functionality
  separately
• Run and debug.