Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

Java unknown host exception

I am trying to access textalertapp.com via HTTP Post request from my android application. But I am getting Unknown host error. Can anybody help me solve this issue.

12-13 01:30:16.058: WARN/System.err(473): java.net.UnknownHostException: textalertapp.com
    12-13 01:30:16.088: WARN/System.err(473):     at java.net.InetAddress.lookupHostByName(InetAddress.java:513)
    12-13 01:30:16.088: WARN/System.err(473):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:278)
    12-13 01:30:16.088: WARN/System.err(473):     at java.net.InetAddress.getAllByName(InetAddress.java:242)
    12-13 01:30:16.088: WARN/System.err(473):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)
    12-13 01:30:16.099: WARN/System.err(473):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
    12-13 01:30:16.099: WARN/System.err(473):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
    12-13 01:30:16.099: WARN/System.err(473):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:348)
    12-13 01:30:16.108: WARN/System.err(473):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
    12-13 01:30:16.118: WARN/System.err(473):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
    12-13 01:30:16.118: WARN/System.err(473):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
    12-13 01:30:16.118: WARN/System.err(473):     at com.textalert.alertCollection.getAlerts(alertCollection.java:46)
    12-13 01:30:16.118: WARN/System.err(473):     at com.textalert.alertsList$1.run(alertsList.java:81)
    12-13 01:30:16.128: WARN/System.err(473):     at java.lang.Thread.run(Thread.java:1096)

Code is

 HttpClient client = new DefaultHttpClient();
                String postURL = "http://textalertapp.com/androidCode/?api=AlertManager&method=getAlerts";
                HttpPost post = new HttpPost(postURL); 

                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("user", "kris"));
                params.add(new BasicNameValuePair("pass", "xyz"));
                UrlEncodedFormEntity ent = new UrlEncodedFormEntity(params,HTTP.UTF_8);
                post.setEntity(ent);
                HttpResponse responsePOST = client.execute(post);  
                HttpEntity resEntity = responsePOST.getEntity();  
                if (resEntity != null) {    
                    Log.i("RESPONSE",EntityUtils.toString(resEntity));
                }
like image 799
Ayaz Alavi Avatar asked Dec 13 '10 09:12

Ayaz Alavi


People also ask

How do you handle an unknown host exception?

The UnknownHostException can be avoided with the following checks: Valid hostname - The hostname should be double checked to make sure it does not contain any typos or whitespaces. DNS settings - The system DNS settings should be checked to ensure that the DNS server is reachable.


3 Answers

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

I just added this line in manifest file. Problem solved

like image 155
Ayaz Alavi Avatar answered Sep 17 '22 13:09

Ayaz Alavi


This means that your host is unknown, i.e. does not exist or is not accessible. Check you IP again and check whether you can get this IP from your device. Probably this IP exists in your local network and is not accessible from outside.

If IP exists check firewall definitions. Firewall cause the same effect.

like image 40
AlexR Avatar answered Sep 19 '22 13:09

AlexR


I just started receiving the "java.net.UnknownHostException" error when fetching content from a URL that previously worked perfectly.

After going around in circles for a while, I manually deleted my project's /bin folder and cleaned the project in Eclipse (Project -> Clean), which fixed this error.

like image 30
Chris Lacy Avatar answered Sep 21 '22 13:09

Chris Lacy