Url fetch

i run this code. it's error. i type what's wrong. Please help me.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
try {
URL urlsearch = new URL("*insert website*");
BufferedReader buffreader = new BufferedReader(
new InputStreamReader(urlsearch.openStream()));
String HTMLdisplay;
while ((HTMLdisplay = buffreader.readLine()) != null) {
System.out.println(HTMLdisplay);
}
buffreader.close();
} catch (MalformedURLException e) {
} catch (IOException e) {
}

error is:
[ERROR] [exam] - Line 52: No source code is available for type
java.net.URL; did you forget to inherit a required module?
[ERROR] [exam] - Line 53: No source code is available for type
java.io.BufferedReader; did you forget to inherit a required module?
[ERROR] [exam] - Line 54: No source code is available for type
java.io.InputStreamReader; did you forget to inherit a required
module?
[ERROR] [exam] - Line 60: No source code is available for type
java.net.MalformedURLException; did you forget to inherit a required
module?
[ERROR] [exam] - Line 95: No source code is available for type
java.net.HttpURLConnection; did you forget to inherit a required
module?

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