content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * Licensed 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://opensource.org/licenses/Apache-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.
   *
   */
  
  
  package com.tencent.angel.common;
  
  import org.apache.hadoop.classification.InterfaceAudience;
  import org.apache.hadoop.classification.InterfaceStability;
  import org.apache.hadoop.io.WritableComparable;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  
  @InterfaceAudience.Public @InterfaceStability.Stable public abstract class Id
    implements WritableComparable<Id> {
    public static final String SEPARATOR = "_";
    protected int index;
  
    /**
     * constructs an ID object from the given int
     */
    public Id(int index) {
      this.index = index;
    }
  
    protected Id() {
    }
  
    /**
     * returns the int which represents the identifier
     */
    public int getIndex() {
      return index;
    }
  
    @Override public String toString() {
      return String.valueOf(index);
    }
  
    @Override public int hashCode() {
      return index;
    }
  
    @Override public boolean equals(Object o) {
      if (this == o)
        return true;
      if (o == null)
        return false;
      if (o.getClass() == this.getClass()) {
        Id that = (Id) o;
        return this.index == that.index;
      } else
        return false;
    }
  
    /**
     * Compare IDs by associated numbers
     */
    public int compareTo(Id that) {
      return this.index - that.index;
    }
  
    public void readFields(DataInput in) throws IOException {
      this.index = in.readInt();
    }
  
    public void write(DataOutput out) throws IOException {
      out.writeInt(index);
    }
  }
  