title: Strange NetworkOnMainThreadException in Android app?
body: <p>The idea is to start a chat. So I have this properties in my class:</p>
  
  <pre><code>private MulticastSocket so;
  private EditText messageBoard;
  private InetAddress serverAddress;
  private int port;
  </code></pre>
  
  <p>Then I have this code in the <code>onCreate()</code> method:</p>
  
  <pre><code>protected void onCreate(Bundle savedInstanceState) {
      // TODO Auto-generated method stub
      super.onCreate(savedInstanceState);
      setContentView(R.layout.second);
  
      // connect to server
      connect();
  
      // Associate a variable with the Button on the interface
      final Button sendButton = (Button) findViewById(R.id.button2);
      sendButton.setOnClickListener(new View.OnClickListener() {
  
          @Override
          public void onClick(View v) {
              // when the button is clicked the next screen is loaded
              sendMessage();
          }
      });
  
  }   // end of onCreate
  </code></pre>
  
  <p>Here is my <code>connect()</code> method:</p>
  
  <pre><code>private void connect() {
  
      port = 4456;
  
      // convert the host name to InetAddress
      try {
          serverAddress = InetAddress.getByName("my server address is here");
      } catch (Exception e) {}
  
      // create socket and start communicating
      try {
          so = new MulticastSocket(port);
          so.joinGroup(serverAddress);
      } catch (IOException e) {}
  
      // start listening for incoming messages
      new Receiver(so, messageBoard);
  }
  </code></pre>
  
  <p>Everything looks right to me but this is what it says:</p>
  
  <pre><code>01-24 23:33:16.277: W/dalvikvm(569): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
  01-24 23:33:16.357: E/AndroidRuntime(569): FATAL EXCEPTION: main
  01-24 23:33:16.357: E/AndroidRuntime(569): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.regeduser00x.proj1/com.regeduser00x.proj1.Second}: android.os.NetworkOnMainThreadException
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.Handler.dispatchMessage(Handler.java:99)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.Looper.loop(Looper.java:137)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.main(ActivityThread.java:4424)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at java.lang.reflect.Method.invokeNative(Native Method)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at java.lang.reflect.Method.invoke(Method.java:511)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at dalvik.system.NativeStart.main(Native Method)
  01-24 23:33:16.357: E/AndroidRuntime(569): Caused by: android.os.NetworkOnMainThreadException
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.getByName(InetAddress.java:295)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at com.regeduser00x.proj1.Second.connect(Second.java:99)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at com.regeduser00x.proj1.Second.onCreate(Second.java:38)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.Activity.performCreate(Activity.java:4465)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
  01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
  01-24 23:33:16.357: E/AndroidRuntime(569):  ... 11 more
  </code></pre>
  
  <p>That <code>Second.java:99</code> happens to be <code>serverAddress = InetAddress.getByName("my server address is here");</code> and line 38 happens to be <code>connect();</code> What's the matter with it? I have tested the line with the InetAddress in a small test program and it works perfectly but here something happens.</p>