api/src/main/java/javax/jdo/identity/ByteIdentity.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * ByteIdentity.java
 *
 */

package javax.jdo.identity;

import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

/**
 * This class is for identity with a single byte field.
 *
 * @version 2.0
 */
public class ByteIdentity extends SingleFieldIdentity<ByteIdentity> {

  private static final long serialVersionUID = 1L;

  /** The key. */
  private byte key;

  /** Construct this instance with the key value. */
  private void construct(byte key) {
    this.key = key;
    hashCode = super.hashClassName() ^ key;
  }

  /**
   * Constructor with class and key.
   *
   * @param pcClass the target class
   * @param key the key
   */
  public ByteIdentity(Class<?> pcClass, byte key) {
    super(pcClass);
    construct(key);
  }

  /**
   * Constructor with class and key.
   *
   * @param pcClass the target class
   * @param key the key
   */
  public ByteIdentity(Class<?> pcClass, Byte key) {
    super(pcClass);
    setKeyAsObject(key);
    construct(key.byteValue());
  }

  /**
   * Constructor with class and key.
   *
   * @param pcClass the target class
   * @param str the key
   */
  public ByteIdentity(Class<?> pcClass, String str) {
    super(pcClass);
    assertKeyNotNull(str);
    construct(Byte.parseByte(str));
  }

  /** Constructor only for Externalizable. */
  public ByteIdentity() {}

  /**
   * Return the key.
   *
   * @return the key
   */
  public byte getKey() {
    return key;
  }

  /**
   * Return the String version of the key.
   *
   * @return the key.
   */
  public String toString() {
    return Byte.toString(key);
  }

  /**
   * Determine if the other object represents the same object id.
   *
   * @param obj the other object
   * @return true if both objects represent the same object id
   */
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    } else if (!super.equals(obj)) {
      return false;
    } else {
      ByteIdentity other = (ByteIdentity) obj;
      return key == other.key;
    }
  }

  /**
   * Determine the ordering of identity objects.
   *
   * @param o Other identity
   * @return The relative ordering between the objects
   * @since 2.2
   */
  public int compareTo(ByteIdentity o) {
    if (o == null) {
      throw new ClassCastException("object is null");
    }
    int result = super.compare(o);
    return (result == 0) ? (key - o.key) : result;
  }

  /**
   * Create the key as an Object.
   *
   * @return the key as an Object
   * @since 2.0
   */
  @Override
  protected Object createKeyAsObject() {
    return Byte.valueOf(key);
  }

  /**
   * Write this object. Write the superclass first.
   *
   * @param out the output
   */
  @Override
  public void writeExternal(ObjectOutput out) throws IOException {
    super.writeExternal(out);
    out.writeByte(key);
  }

  /**
   * Read this object. Read the superclass first.
   *
   * @param in the input
   */
  @Override
  public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
    super.readExternal(in);
    key = in.readByte();
  }
}