How to fix Java HTTP java.net.UnknownHostException


You may get UnknownHostException if the URL that you have formed for your Java HTTP connection does not exist.

Let's take an example where I try to connect to https://code2care1234.org, if you try this URL on your web browser you will see that this domain does not exist. So if you try to reach such a domain either using HTTP Get or Post methods you will get this exception.

Example:
try {

  URL url = new URL("http://code2care1234.org");
  HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
  httpURLConnection.setRequestMethod("POST");
  httpURLConnection.getInputStream();
            
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
}
Output Stack Trace:
java.net.UnknownHostException: code2care1234.org
	at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:220)
	at java.base/java.net.Socket.connect(Socket.java:609)
	at java.base/java.net.Socket.connect(Socket.java:558)
	at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:182)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
	at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1592)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1520)
	at HTTPExample.main(HTTPExample.java:22)
UnknownHostException Java HTTP Error
Java: UnknownHostException
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