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copied!<p>Ok, implemented it myself in the end. I did a speed comparison, and found when compared to a HashMap that it was still slightly faster with 4 entries, but slower with 5 or more. I did the tests with a longish list of keys that I tried to give a similar makeup as a list of random english words.</p> <pre><code>import java.util.*; // PUBLIC DOMAIN public class SmallMap extends AbstractMap { private Entry entry = null; public void clear() { entry = null; } public boolean isEmpty() { return entry==null; } public int size() { int r = 0; for(Entry e = entry; e!=null; e = e.next) r++; return r; } public boolean containsKey(Object key) { for(Entry e = entry; e!=null; e = e.next){ if(e.key.equals(key)){ return true; } } return false; } public boolean containsValue(Object value) { for(Entry e = entry; e!=null; e = e.next){ if(e.value==null){ if(value==null) return true; }else if(e.value.equals(value)){ return true; } } return false; } public Object get(Object key) { for(Entry e = entry; e!=null; e = e.next){ if(e.key.equals(key)){ return e.value; } } return null; } public Object put(Object key, Object value) { for(Entry e = entry; e!=null; e = e.next){ if(e.key.equals(key)){ Object r = e.value; e.value = value; return r; } } entry = new Entry(key, value, entry); return null; } public Object remove(Object key) { if(entry!=null){ if(entry.key.equals(key)){ Object r = entry.value; entry = entry.next; return r; } for(Entry e = entry; e.next!=null; e = e.next){ if(key.equals(e.next.key)){ Object r = e.next.value; e.next = e.next.next; return r; } } } return null; } public Set entrySet() { return new EntrySet(); } class EntrySet extends AbstractSet{ public Iterator iterator() { return new Iterator(){ Entry last = null; Entry e = entry; public boolean hasNext() { return e!=null; } public Object next() { last = e; e = e.next; return last; } public void remove() { if(last == null) throw new IllegalStateException(); SmallMap.this.remove(last.key); } }; } public int size() { return SmallMap.this.size();} } static private class Entry implements java.util.Map.Entry { final Object key; Object value; Entry next; Entry(Object key, Object value, Entry next){ if(key==null) throw new NullPointerException(); this.key = key; this.value = value; this.next = next; } public Object getKey() { return key; } public Object getValue() { return value; } public Object setValue(Object value) { Object r = this.value; this.value = value; return r; } public int hashCode() { return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode()); } } } </code></pre>

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