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A micro-lib providing a threadsafe map which provides optimistic concurrency control.

There is a newer version: 1.2

/*
 * Written by Cliff Click and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

package org.vvcephei.occ_map;

import java.util.Map;

/**
 * A simple implementation of {@link java.util.Map.Entry}.
 * Does not implement {@link java.util.Map.Entry.setValue}, that is done by users of the class.
 *
 * Copied from https://github.com/boundary/high-scale-lib @ 3654434eda00b68d37d22dcd70e4f65db9432d06
 * @author Cliff Click
 * @param  the type of keys maintained by this map
 * @param  the type of mapped values
 */

abstract class AbstractEntry implements Map.Entry {
  /** Strongly typed key */
  protected final TypeK _key;
  /** Strongly typed value */
  protected       TypeV _val;

  public AbstractEntry(final TypeK key, final TypeV val) { _key = key;        _val = val; }
  public AbstractEntry(final Map.Entry e) { _key = e.getKey(); _val = e.getValue(); }
  /** Return "key=val" string */
  public String toString() { return _key + "=" + _val; }
  /** Return key */
  public TypeK getKey  () { return _key;  }
  /** Return val */
  public TypeV getValue() { return _val;  }

  /** Equal if the underlying key & value are equal */
  public boolean equals(final Object o) {
    if (!(o instanceof Map.Entry)) return false;
    final Map.Entry e = (Map.Entry)o;
    return eq(_key, e.getKey()) && eq(_val, e.getValue());
  }

  /** Compute "key.hashCode() ^ val.hashCode()" */
  public int hashCode() {
    return
      ((_key == null) ? 0 : _key.hashCode()) ^
      ((_val == null) ? 0 : _val.hashCode());
  }

  private static boolean eq(final Object o1, final Object o2) {
    return (o1 == null ? o2 == null : o1.equals(o2));
  }
}