FindBugs warning: Inefficient use of keySet iterator instead of entrySet iterator

Question

Please refer to the following method :

public Set getCellsInColumn(String columnIndex){
    Map cellsMap = getCell         


        

Answer 1

You're getting the set of keys in the map, then using each key to get the value out of the map.

Instead, you can simply iterate through the Map.Entry key/value pairs returned to you via entrySet(). That way you avoid the relatively expensive get() lookup (note the use of the word relatively here)

e.g.

for (Map.Entry e : map.entrySet()) {
   // do something with...
   e.getKey();
   e.getValue();
}