Aggregation.java

package org.ggp.base.apps.research;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeSet;

/**
 * Aggregation is a way of storing data about an unordered collection, mapping
 * each element to an associated data object, and then visualizing the data by
 * sorting the elements by their associated data and printing out the sorted list.
 * The data objects must be comparable to each other, so they can be sorted.
 *
 * @author Sam Schreiber
 */
public abstract class Aggregation<T extends Comparable<T>>
{
    private final Map<String, T> entryData = new HashMap<String, T>();

    boolean containsEntry(String key) {
        return entryData.containsKey(key);
    }

    void createEntry(String key, T data) {
        entryData.put(key, data);
    }

    T getEntryData(String key) {
        return entryData.get(key);
    }

    private final class EntryComparator implements Comparator<Map.Entry<String,T>> {
        @Override
        public int compare(Map.Entry<String,T> a, Map.Entry<String,T> b) {
            return a.getValue().compareTo(b.getValue());
        }

    }

    @Override
    public String toString() {
        int nMaxLength = 0;
        StringBuilder theStringRep = new StringBuilder();
        TreeSet<Map.Entry<String,T>> theEntries = new TreeSet<Map.Entry<String,T>>(new EntryComparator());
        theEntries.addAll(entryData.entrySet());
        for (Map.Entry<String,T> entry : theEntries) {
            nMaxLength = Math.max(nMaxLength, entry.getKey().length());
        }
        for (Map.Entry<String,T> entry : theEntries) {
            theStringRep.append(String.format("%1$-" + (nMaxLength + 5) + "s", entry.getKey()) + entry.getValue() + "\n");
        }
        return theStringRep.toString();
    }
}