Get nothing when read url to string

Question

I try to read a json string from a url:

String message = "http://cs-server.usc.edu:12695/examples/servlet/Moviefb?title=batman&title_type=feature";

    URL website;
    String str1 = "";

    try {
        website = new URL(message);
        URLConnection connection = website.openConnection();

        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));

        String inputLine;
        while ((inputLine = in.readLine()) != null) 
            str1 += inputLine;

    } catch (MalformedURLException e1) {
        // TODO Auto-generated catch block
Toast.makeText(getBaseContext(), 
                    "catch1", 
                    Toast.LENGTH_LONG).show();
        e1.printStackTrace();
    } catch (Exception e) {

Toast.makeText(getBaseContext(), 
                "catch2", 
                Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }

And then I use Toastto show what's in str1

Toast.makeText(getBaseContext(), 
                str1, 
                Toast.LENGTH_LONG).show();

But I get nothing. And I got an exception,it shows catch2. These code are in my Android Application Project in Eclipse.

When I copy and past these code to my ordinary Java Project, it works.

the new stacktrace:

        12-13 09:02:28.909: W/System.err(1015): java.lang.SecurityException: Permission denied (missing INTERNET permission?)
12-13 09:02:28.949: W/System.err(1015):     at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
12-13 09:02:29.079: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:29.149: W/System.err(1015):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
12-13 09:02:29.159: W/System.err(1015):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
12-13 09:02:29.179: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:29.219: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:29.239: W/System.err(1015):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
12-13 09:02:29.328: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:29.428: W/System.err(1015):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
12-13 09:02:29.549: W/System.err(1015):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
12-13 09:02:29.609: W/System.err(1015):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
12-13 09:02:29.669: W/System.err(1015):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
12-13 09:02:29.669: W/System.err(1015):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
12-13 09:02:29.719: W/System.err(1015):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
12-13 09:02:29.819: W/System.err(1015):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
12-13 09:02:29.879: W/System.err(1015):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
12-13 09:02:29.959: W/System.err(1015):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)
12-13 09:02:29.959: W/System.err(1015):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:177)
12-13 09:02:29.959: W/System.err(1015):     at com.example.hwnine.Show$1.doInBackground(Show.java:48)
12-13 09:02:30.229: W/System.err(1015):     at com.example.hwnine.Show$1.doInBackground(Show.java:1)
12-13 09:02:30.268: W/System.err(1015):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
12-13 09:02:30.268: W/System.err(1015):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
12-13 09:02:30.308: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:30.308: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:30.348: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:30.368: W/System.err(1015):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
12-13 09:02:30.398: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0
12-13 09:02:30.479: W/System.err(1015):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
12-13 09:02:30.489: W/System.err(1015):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
12-13 09:02:30.499: W/System.err(1015):     at java.lang.Thread.run(Thread.java:856)
12-13 09:02:30.499: W/System.err(1015): Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
12-13 09:02:30.519: W/System.err(1015):     at libcore.io.Posix.getaddrinfo(Native Method)
12-13 09:02:30.519: W/System.err(1015):     at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:59)
12-13 09:02:30.529: W/System.err(1015):     at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
12-13 09:02:30.539: W/System.err(1015):     ... 21 more
12-13 09:02:30.539: W/System.err(1015): Caused by: libcore.io.ErrnoException: getaddrinfo failed: EACCES (Permission denied)
12-13 09:02:30.559: W/System.err(1015):     ... 24 more
12-13 09:02:30.589: W/Trace(1015): Unexpected value from nativeGetEnabledTags: 0

any chance you are running this code on ui thread? newer sdk does not allow that — Vladimir
– Vladimir, Commented Dec 13, 2012 at 8:31

Vladimir · Accepted Answer · 2012-12-13 08:51:31Z

1

If you run this code on Android 3.0+ you will probably get NetworkOnMainThreadException, since it looks like you do this on the main thread. You need to use AsyncTask for this types of tasks.

What you can do is:

final String message = "http://cs-server.usc.edu:12695/examples/servlet/Moviefb?title=batman&title_type=feature";

new AsyncTask<Void, Void, String>() {
    private String mErrDesc = null;

    @Override
    protected String doInBackground(Void... paramArrayOfParams) {
       URL website;
       String str1 = null;

       try {
           website = new URL(message);
           URLConnection connection = website.openConnection();

           BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));

           String inputLine;
           while ((inputLine = in.readLine()) != null) 
               str1 += inputLine;

        } catch (MalformedURLException e1) {
            mErrDesc = "MalformedURLException thrown";
            e1.printStackTrace();
            return null;
        } catch (Exception e) {
            mErrDesc = "Exception thrown";
            e.printStackTrace();
            return null;
        }

        return str1;
    }

    @Override 
    protected void onPostExecute(String str) {
        if (str != null)
            Toast.makeText(getBaseContext(), str, Toast.LENGTH_LONG).show();
        else if (mErrDesc != null) 
            Toast.makeText(getBaseContext(), mErrDesc, Toast.LENGTH_LONG).show();
        else 
            Toast.makeText(getBaseContext(), "Unknown error", Toast.LENGTH_LONG).show();
    }

}.execute();

edited Dec 13, 2012 at 8:51

answered Dec 13, 2012 at 8:39

Vladimir

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6 Comments

user23256 Over a year ago

My Android platform is 4.2

Vladimir Over a year ago

So you will get the exception. I'll update my answer with sample solution of how to avoid this

Vladimir Over a year ago

@user1767718 which exception do you get?

Vladimir Over a year ago

what do you get in stacktrace? you can also modify the line mErrDesc = "Exception thrown"; to mErrDesc = "Exception thrown: " + ex.getMessage(); to get the exception in your toast

Vladimir Over a year ago

You need to add <uses-permission android:name="android.permission.INTERNET"/> to your AndroidManifest.xml

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ƒernando Valle · Accepted Answer · 2012-12-13 08:42:01Z

0

Maybe it depends for what Android platform are you building. Not is the same build for 2.3 or 4.0. If you are building for 2.2 or less than 3.0 use HttpClient. here an example.

answered Dec 13, 2012 at 8:42

ƒernando Valle

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