Android emulator to real device issue

Question

I have this code which is getting the text from a website, and changing a label on the Android program to the last line from the buffered reader

EDIT - I have updated the code thanks to the kind advice of Mohsen Afshin

button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Thread t = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        URL url = new URL(
                                "http://webpage.php");

                        URLConnection yc = url.openConnection();
                        yc.setDoOutput(true);
                        PrintStream ps = new PrintStream(yc
                                .getOutputStream());
                        ps.print("Name=Joe");
                        BufferedReader in = new BufferedReader(
                                new InputStreamReader(yc.getInputStream()));
                        String inputLine;
                        while ((inputLine = in.readLine()) != null)
                            display.setText(inputLine);
                        in.close();
                    } catch (IOException e) { // TODO Auto-generated catch
                                                // block
                        e.printStackTrace();
                        display.setText("failed");
                    }
                }
            });

            t.start();

Now this is working absolutely fine on the emulator. However when I have put it onto an Android device it is crashing. I have changed the Android Manifest to allow internet connections -

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

I am not sure where the problem is. On a strange note, it has worked once! and will not work again. The logcat is as follows -

06-25 16:18:15.918: W/dalvikvm(9047): threadid=11: thread exiting with uncaught exception (group=0x411432a0) 06-25 16:18:15.923: E/AndroidRuntime(9047): FATAL EXCEPTION: Thread-599 06-25 16:18:15.923: E/AndroidRuntime(9047): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4925) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:950) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.View.requestLayout(View.java:15461) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.View.requestLayout(View.java:15461) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.View.requestLayout(View.java:15461) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.View.requestLayout(View.java:15461) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:292) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.view.View.requestLayout(View.java:15461) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.widget.TextView.checkForRelayout(TextView.java:6644) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.widget.TextView.setTex t(TextView.java:3732) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.widget.TextView.setText(TextView.java:3590) 06-25 16:18:15.923: E/AndroidRuntime(9047): at android.widget.TextView.setText(TextView.java:3565) 06-25 16:18:15.923: E/AndroidRuntime(9047): at gaz.helloworld.MainActivity$2$1.run(MainActivity.java:59) 06-25 16:18:15.923: E/AndroidRuntime(9047): at java.lang.Thread.run(Thread.java:856)

Can anyone more knowledgeable help me please?

Answer 1

You might be getting a NetworkOnMainThreadException .

Sometimes there are network problems on main UI(Activity)

You should use a separate thread, refer to this post

Answer 2

As stated by @NinadChilap, it will generate a NetworkOnMainThreadException .

So this will work if your URL is valid:

Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //To change body of implemented methods use File | Settings | File Templates.
                    URL url = new URL("http://weblink.php");

                    URLConnection yc = url.openConnection();
                    yc.setDoOutput(true);
                    PrintStream ps = new PrintStream(yc.getOutputStream());
                    ps.print("Name=Joe");
                    BufferedReader in = new BufferedReader(
                            new InputStreamReader(yc.getInputStream()));
                    String inputLine;
                    while ((inputLine = in.readLine()) != null)
                        display.setText(inputLine);
                    in.close();
                } catch (IOException e) { // TODO Auto-generated catch block
                    e.printStackTrace();
                    display.setText("failed");
                }
            }
        });

        t.start();