Inefficient use of keySet iterator instead of entrySet iterator JAVA-P0361
Performance
Major
6 months ago
—
a year old
Use entrySet instead of keySet here.
188 }
189
190 // check correction
191 for (var id : visitor.idCommentMap.keySet()) {192 LOG.debug("id: {}", id);
193
194 List<Token> comments = visitor.idCommentMap.get(id);Use entrySet instead of keySet here.
171 expectedIdCommentMap.put("linkageSpecification4", "linkageSpecification4");
172
173 // check completeness
174 for (var id : expectedIdCommentMap.keySet()) {175 LOG.debug("id: {}", id);
176
177 List<Token> comments = visitor.idCommentMap.get(id);
Description
This method accesses the value of a Map entry, using a key that was retrieved from a keySet iterator.
It is more efficient to use an iterator on the entrySet of the map, to avoid the Map.get(key) lookup.
Bad Practice
for (String key: map.keySet()) {
...
if (satisfiesCriteria(key))
value = map.get(key); // Inefficient
...
}
Recommended
for (Map.Entry<String, Integer> entry : map.entrySet()) {
...
if (satisfiesCriteria(entry.getKey())
value = entry.getValue();
...
}
While the performance benefits of this change may not be very high for smaller maps, it is worth making this change if you will be handling maps with very large capacities (entry count in the millions for example), and/or slower or bad hashing implementations.
References
- SpotBugs - WMI_WRONG_MAP_ITERATOR