The equals and hashCode methods of java.net.URL both make calls out to the Internet and are blocking operations. URI on the other hand makes no such calls and should be used instead unless the specific URL functionality is required.

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
    // ...
  }
}