insertionsortedmap.java

java 写的一个新闻发布系统

package org.jahia.utils;

import java.util.*;


/**
 * <p>Title: Map implementation that respects the insertion order.</p>
 * <p>Description: This map implementation actually uses an ArrayList to
 * store the entry pairs.</p>
 * <p>Copyright: Copyright (c) 2002</p>
 * <p>Company: Jahia Ltd</p>
 * @author Serge Huber
 * @version 1.0
 *
 */

public class InsertionSortedMap extends AbstractMap {

    private ArrayList internalList = new ArrayList();

    private class Entry implements Map.Entry {

        private Object key;
        private Object value;

        public Entry(Object key, Object value) {
            this.key = key;
            this.value = value;
        }

        public boolean equals (Object o) {
            if (! (o instanceof Entry)) {
                return false;
            }
            Entry e2 = (Entry) o;
            if ( (this.getKey() == null ?
                  e2.getKey() == null : this.getKey().equals(e2.getKey())) &&
                (this.getValue() == null ?
                 e2.getValue() == null : this.getValue().equals(e2.getValue()))) {
                return true;
            } else {
                return false;
            }

        }

        public int hashCode() {
           return  ((this.getKey()==null   ? 0 : this.getKey().hashCode()) ^
                    (this.getValue()==null ? 0 : this.getValue().hashCode()));
        }

        public Object getKey() {
            return key;
        }

        public Object getValue() {
            return value;
        }

        public Object setValue(Object value) {
            Object oldValue = this.value;
            this.value = value;
            return oldValue;
        }

    }

    public InsertionSortedMap() {
    }

    public InsertionSortedMap(Map t) {
        // we must now build the key order based on the map we were passed.
        Iterator sourceEntryIter = t.entrySet().iterator();
        while (sourceEntryIter.hasNext()) {
            Map.Entry curEntry = (Map.Entry) sourceEntryIter.next();
            internalList.add(curEntry.getKey());
        }
    }

    public Set entrySet() {
        InsertionSortedSet insertionSortedSet = new InsertionSortedSet();
        insertionSortedSet.setInternalList(internalList);
        return insertionSortedSet;
    }

    public Object put(Object key,
                      Object value)
        throws     UnsupportedOperationException ,
        ClassCastException ,
        IllegalArgumentException ,
        NullPointerException {
        int pos = findKey(key);
        if (pos == -1) {
            Entry newEntry = new Entry(key, value);
            internalList.add(newEntry);
            return null;
        } else {
            Entry existingEntry = (Entry) internalList.get(pos);
            Object oldValue = existingEntry.getValue();
            existingEntry.setValue(value);
            return oldValue;
        }
    }

    private int findKey(Object key) {
        int pos = -1;
        Iterator listIter = internalList.iterator();
        while (listIter.hasNext()) {
            Map.Entry curEntry = (Map.Entry) listIter.next();
            pos++;
            if (curEntry.getKey().equals(key)) {
                return pos;
            }
        }
        return -1;
    }

}