When only the keys from a map are needed in a loop, iterating the keySet makes sense. But when both the key and the value are needed, it's more efficient to iterate the entrySet, which will give access to both the key and value, instead.

Noncompliant Code Example

public void doSomethingWithMap(Map<String,Object> map) {

  for (String key : map.keySet()) {  // Noncompliant; for each key the value is retrieved

    Object value = map.get(key);

    // ...

  }

}

Compliant Solution

public void doSomethingWithMap(Map<String,Object> map) {

  for (Map.Entry<String,Object> entry : map.entrySet()) {

    String key = entry.getKey();

    Object value = entry.getValue();

    // ...

  }

}