You could create a new class like this to limit the size of a HashMap:
public class MaxSizeHashMap<K, V> extends LinkedHashMap<K, V> {
private final int maxSize;
public MaxSizeHashMap(int maxSize) {
this.maxSize = maxSize;
}
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > maxSize;
}
}