Checking If Page is up on Android causes a crash?

Question

I'm quite new to Android. I have done some work in Java so I went back and found my site status checker.

What I was thinking is that because Android is based off of Java I could just copy over to the Android app.

This is my snippet:

public boolean checkIfSite(String url) {
    HttpURLConnection connection = null;
    try {
        URL u = new URL(url);
        connection = (HttpURLConnection) u.openConnection();
        connection.setRequestMethod("HEAD");
        int code = connection.getResponseCode();
        System.out.println("" + code);
        // You can determine on HTTP return code received. 200 is success.

        return true;
    } catch (MalformedURLException e) {
        e.printStackTrace();
        return false;
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    } finally {
        if (connection != null) {
            connection.disconnect();
        }
    }
}

I call it with:

if (checkIfSite("http://google.com")) {
//CODE
}

This is the trace I get:

    01-05 08:58:49.683: D/AndroidRuntime(9767): Shutting down VM
01-05 08:58:49.683: W/dalvikvm(9767): threadid=1: thread exiting with uncaught exception (group=0x40a211f8)
01-05 08:58:49.691: E/AndroidRuntime(9767): FATAL EXCEPTION: main
01-05 08:58:49.691: E/AndroidRuntime(9767): android.os.NetworkOnMainThreadException
01-05 08:58:49.691: E/AndroidRuntime(9767):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at java.net.InetAddress.getAllByName(InetAddress.java:220)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at libcore.net.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:479)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at com.sonyericsson.extras.liveview.plugins.sandbox.SandboxPluginService.checkIfSite(SandboxPluginService.java:184)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at com.sonyericsson.extras.liveview.plugins.sandbox.SandboxPluginService.button(SandboxPluginService.java:209)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at com.sonyericsson.extras.liveview.plugins.AbstractPluginService$LiveViewCallback$3.run(AbstractPluginService.java:200)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at android.os.Handler.handleCallback(Handler.java:605)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at android.os.Looper.loop(Looper.java:137)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at android.app.ActivityThread.main(ActivityThread.java:4424)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at java.lang.reflect.Method.invokeNative(Native Method)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at java.lang.reflect.Method.invoke(Method.java:511)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
01-05 08:58:49.691: E/AndroidRuntime(9767):     at dalvik.system.NativeStart.main(Native Method)

What happens? Can you post a stack trace? – Oleg Vaskevich Jan 05 '13 at 15:56 — Oleg Vaskevich, Jan 05 '13 at 15:56
make sure you have added `` permission in Manifest – ρяσѕρєя K Jan 05 '13 at 15:57 — ρяσѕρєя K, Jan 05 '13 at 15:57

score 2 · Accepted Answer · edited May 23 '17 at 12:12

2

Did you think about allowing your App to go online by adding a permission to AndroidMainfest.xml file? The file is located on the top level of your project structure like your src and res folder.

<manifest xlmns:android...>
   <uses-permission android:name="android.permission.INTERNET"></uses-permission>
   ...
</manifest>

Your exception is thrown when you try to do a networking operation on the UI-Thread. Solution over here...

More infos about AsyncTask:

edited May 23 '17 at 12:12

Community

1
1

answered Jan 05 '13 at 15:57

Chris

4,403
4
42
54

Nope. I added it in my file and it still crashes with the same exception – Allison Jan 05 '13 at 16:06
I thought using the UI thread would only block UI updates of the device. (Argh... iOS was easier for me) – Allison Jan 05 '13 at 16:14

Oleg Vaskevich · Answer 2 · 2013-01-06T02:59:15.340

1

You should first verify that you have the INTERNET permission within your AndroidManifest.xml file.

In addition, on some devices you may get a NetworkOnMainThreadException. The best way to avoid that would be to do the network operations in a different thread, for example by using an AsyncTask.

edited Jan 06 '13 at 02:59

answered Jan 05 '13 at 16:02

Oleg Vaskevich

12,444
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Checking If Page is up on Android causes a crash?

2 Answers2