Check connection to server

Question

I am a newbie to Android and Java, to a lesser extent, so forgive me if this question is ridiculous. **I am also sorry if this post is horribly formatted please understand I am new here, yes the instructions are everywhere but I don't know how to add follow up posts so I just edited the original post and added the new info I received.

I have an activity in an Android project that has to check if it can connect to a server. I simply have a button that when clicked will run code to check server connection.

When I click the button the application shuts down (Unfortunately .... has stopped).

If needed I can provide the full error log. Here is the code I have:

Notes: R.id.check_text refers to a TextView in the layout XML

I need this text to change given the results of isConnectedToServer method.

public class StartActivity extends Activity {

public static final int timeout = 3000;
public static final String TAG = "StartActivity";
public static final String url = "http://serverIP:port";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_start);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_start, menu);
    return true;
}

public boolean isConnectedToServer(String url, int timeout) {
    try {
        URL serverURL = new URL(url);
        URLConnection urlconn = serverURL.openConnection();
        urlconn.setConnectTimeout(timeout);
        urlconn.connect();
        return true;
    } catch (IOException e) {
        Log.e(TAG, e.getLocalizedMessage(), e);
    } catch (IllegalStateException e) {
        Log.e(TAG, e.getLocalizedMessage(), e);
    }
    return false;   

}
public void connectionReturn(View view) {
    boolean a;
    a = this.isConnectedToServer(url, timeout);
    if (a == true) {
        EditText edConnStatus = (EditText) findViewById(R.id.check_text);
        edConnStatus.setText("Connection established");

    } else {
        EditText edConnStatus = (EditText) findViewById(R.id.check_text);
        edConnStatus.setText("Connection to server could not be established");
    }

}
}

And of course in my layout XML I have a Button that reads something like this:

    <Button
    android:id="@+id/bn_checkconnection"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="connectionReturn"
    android:text="@string/checkservconn" />

I appreciate any help that can be given and thank you all.

RECENT EDIT: I changed the connectionReturn method to have the parameters View view (ie. connectionReturn(View vw)) and saw a mistakes with onClick, now it calls the connectionReturn method. I don't get the same errors, I get new ones now! When I click the button the app freezes and Eclipse opens up Socket.class and that says:

Source not found The JAR file c:...\androidsdk\platforms\android17\android.jar has no source attachment Attach the source below....

AND

The Debug window view in Eclipse pops up with this:

Thread [<1> main] (Suspended (exception NetworkOnMainThreadException))

Socket.connect(SocketAddress, int) line: 849<-- It points to this immediately.
HttpConnection.(HttpConnection$Address, int) line: 76 HttpConnection.(HttpConnection$Address, int, HttpConnection$1) line: 50
HttpConnection$Address.connect(int) line: 340
HttpConnectionPool.get(HttpConnection$Address, int) line: 87
HttpConnection.connect(URI, SSLSocketFactory, Proxy, boolean, int) line: 128
HttpEngine.openSocketConnection() line: 316 HttpEngine.connect() line: 311
HttpEngine.sendSocketRequest() line: 290
HttpEngine.sendRequest() line: 240
HttpURLConnectionImpl.connect() line: 81
StartActivity.isConnectedToServer(String, int) line: 37 StartActivity.connectionReturn(View) line: 50
Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]
Method.invoke(Object, Object...) line: 511
View$1.onClick(View) line: 3592 Button(View).performClick() line: 4202
View$PerformClick.run() line: 17340 Handler.handleCallback(Message) line: 725
ViewRootImpl$ViewRootHandler(Handler).dispatchMessage(Message) line: 92 Looper.loop() line: 137 ActivityThread.main(String[]) line: 5039
Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]
Method.invoke(Object, Object...) line: 511
ZygoteInit$MethodAndArgsCaller.run() line: 793
ZygoteInit.main(String[]) line: 560 NativeStart.main(String[]) line: not available [native method]

Ronak Mehta Ronak Mehta · Accepted Answer · 2013-01-01T09:03:47

you can use this function to know whether link is up , internet is connected or not

public boolean isConnected() {
    try {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();

        if (netInfo != null && netInfo.isConnected()) {
            // Network is available but check if we can get access from the
            // network.
            URL url = new URL("www.google.com");
            HttpURLConnection urlc = (HttpURLConnection) url
                    .openConnection();
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(2000); // Timeout 2 seconds.
            urlc.connect();

            if (urlc.getResponseCode() == 200) // Successful response.
            {
                return true;
            } else {
                Log.d("NO INTERNET", "NO INTERNET");
                showToast("URL down");
                return false;
            }
        } else {
            showToast("No Internet Connection");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}

Check connection to server

2 Answers