I need a comparator for a TreeMap. Should I write this anonymously in the constructor for my TreeMap? How else could I write my comparator. Currently, Java does not like my code (can I do this anonymously?):
SortedMap<String, Double> myMap =
new TreeMap<String, Double>(new Comparator<Entry<String, Double>>()
{
public int compare(Entry<String, Double> o1, Entry<String, Double> o2)
{
return o1.getValue().compareTo(o2.getValue());
}
});
This question is related to
java
comparator
treemap
sortedmap
The comparator should be only for the key, not for the whole entry. It sorts the entries based on the keys.
You should change it to something as follows
SortedMap<String, Double> myMap =
new TreeMap<String, Double>(new Comparator<String>()
{
public int compare(String o1, String o2)
{
return o1.compareTo(o2);
}
});
Update
You can do something as follows (create a list of entries in the map and sort the list base on value, but note this not going to sort the map itself) -
List<Map.Entry<String, Double>> entryList = new ArrayList<Map.Entry<String, Double>>(myMap.entrySet());
Collections.sort(entryList, new Comparator<Map.Entry<String, Double>>() {
@Override
public int compare(Entry<String, Double> o1, Entry<String, Double> o2) {
return o1.getValue().compareTo(o2.getValue());
}
});
you can swipe the key and the value. For example
String[] k = {"Elena", "Thomas", "Hamilton", "Suzie", "Phil"};
int[] v = {341, 273, 278, 329, 445};
TreeMap<Integer,String>a=new TreeMap();
for (int i = 0; i < k.length; i++)
a.put(v[i],k[i]);
System.out.println(a.firstEntry().getValue()+"\t"+a.firstEntry().getKey());
a.remove(a.firstEntry().getKey());
System.out.println(a.firstEntry().getValue()+"\t"+a.firstEntry().getKey());
Source: Stackoverflow.com