ArrayListの要素をソートすれば、CombinationKeyMapになるかも。
import java.util.*;public class PermutationKeyMap {
private Map body = new HashMap();
public int size() {
return body.size();
}public boolean isEmpty() {
return body.isEmpty();
}public boolean containsKey(Object key1, Object key2) {
return body.containsKey(permutableKey(key1, key2));
}public boolean containsValue(Object value) {
return body.containsValue(value);
}public Object get(Object key1, Object key2) {
return body.get(permutableKey(key1, key2));
}public Object put(Object key1, Object key2, Object value) {
return body.put(permutableKey(key1, key2), value);
}public Object remove(Object key1, Object key2) {
return body.remove(permutableKey(key1, key2));
}public void putAll(PermutableKeyMap t) {
body.putAll(t.body);
}public void clear() {
body.clear();
}public Set keySet() {
return body.keySet();
}public Collection values() {
return body.values();
}public Set entrySet() {
return body.entrySet();
}public boolean equals(Object o) {
return (o instanceof PermutableKeyMap)
&& body.equals(((PermutableKeyMap) o).body);
}public int hashCode() {
return body.hashCode();
}private List permutableKey(Object key1, Object key2) {
List key = new ArrayList();
key.add(key1);
key.add(key2);
return key;
}}
