Why is this an issue?
The equals and hashCode methods of java.net.URL both may trigger a name service (usually DNS) lookup to
resolve the host name or IP address. Depending on the configuration, and network status, that can take a long time. URI on the other hand
makes no such calls and should be used instead unless the specific URL functionality is required.
In general it is better to use the URI class until access to the resource is actually needed, at which point you can just convert the
URI to a URL using URI.toURL().
This rule checks for uses of URL 's in Map and Set , and for explicit calls to the equals and
hashCode methods.
Noncompliant code example
public void checkUrl(URL url) {
Set<URL> sites = new HashSet<URL>(); // Noncompliant
URL homepage = new URL("http://sonarsource.com"); // Compliant
if (homepage.equals(url)) { // Noncompliant
// ...
}
}
Compliant solution
public void checkUrl(URL url) {
Set<URI> sites = new HashSet<URI>(); // Compliant
URI homepage = new URI("http://sonarsource.com"); // Compliant
URI uri = url.toURI();
if (homepage.equals(uri)) { // Compliant
// ...
}
}
