How to fix UnknownHostException in Java, calling rest-api?

Question

I have a simple rest-api call but I keep getting unknownHostException even after changing to a different Test API. I've never really done anything with rest-api. Below I have added the Stacktrace. When I open the website that I'm trying to access I can see all the Content.

java.net.UnknownHostException: dummy.restapiexample.com
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
    at sun.net.www.http.HttpClient.<init>(HttpClient.java:211)
    at sun.net.www.http.HttpClient.New(HttpClient.java:308)
    at sun.net.www.http.HttpClient.New(HttpClient.java:326)
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1168)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1104)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:998)
    at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:932)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1282)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1257)
    at restApi.MainApp.main(MainApp.java:26)

public static void main(String[] args) {
        URL url;
        try {
            url = new URL("http://dummy.restapiexample.com/api/v1/employees");
            String query = "";
            //make connection
            URLConnection urlc = url.openConnection();

            //use post mode
            urlc.setDoOutput(true);
            urlc.setAllowUserInteraction(false);

            //send query
            PrintStream ps = new PrintStream(urlc.getOutputStream());
            ps.print(query);
            ps.close();

            //get result
            BufferedReader br = new BufferedReader(new InputStreamReader(urlc
                .getInputStream()));
            String l = null;
            while ((l=br.readLine())!=null) {
                System.out.println(l);
            }
            br.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }```

Answer 1

unknownHostException is thrown when java fails to to convert the given name to ip.

Please do check the following ,

1.Hostname is correct

2.Internet access (Try to ping the site and see the name converted to ip)

3.Firewall blocking.

Answer 2

您是否尝试过ResteasyClient，它的设置要容易得多。