1. 첫번째 방법
importjava.util.*;
public class filt
{
public static void main(String[] args)
{
// sorted map of cities
Hashtable hashtable = new Hashtable();
hashtable.put("new york", "yankees");
hashtable.put("boston", "red sox");
hashtable.put("st. louis", "cardinals");
hashtable.put("arizona", "cardinals");
// arizona might as well be 'phoenix'
String[] cities2ignore = { "new york", "boston" };
TreeSet citiesOfInterest = new TreeSet();
citiesOfInterest.addAll( hashtable.keySet() );
citiesOfInterest.removeAll( Arrays.asList(cities2ignore) );
Iterator iterator = citiesOfInterest.iterator();
while( iterator.hasNext() ) {
System.out.println( iterator.next() );
}
}
}
2. 두번째 방법
public class SortHashtable {
public static void main(String[] args) {
// Create and populate hashtable
Hashtable ht = new Hashtable();
ht.put("ABC", "abc");
ht.put("XYZ","xyz");
ht.put("MNO", "mno");
// Sort hashtable.
Vector v = new Vector(ht.keySet());
Collections.sort(v);
// Display (sorted) hashtable.
for (Enumeration e = v.elements(); e.hasMoreElements();) {
String key = (String)e.nextElement();
String val = (String)ht.get(key);
System.out.println("Key: " + key + " Val: " + val);
}
}
}
3. 세번째 방법(Key, Value 정렬)
SortedSet entries = new TreeSet(new EntryValueComparator());
entries.addAll(first.entrySet());
public class EntryValueComparator implements Comparator{
public int compare(Object o1, Object o2) {
return compare((Map.Entry)o1, (Map.Entry)o2);
}
public int compare(Map.Entry e1, Map.Entry e2) {
int cf = ((Comparable)e1.getValue)().compareTo(e2.getValue());
if (cf == 0) {
cf = ((Comparable)e1.getKey()).compareTo(e2.getKey());
}
return cf;
}
}
