content: /*
   * Copyright 2021 4Paradigm
   *
   * 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
   *
   *   http://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.
   */
  
  package com._4paradigm.openmldb.common;
  
  import java.io.Serializable;
  
  public class Pair<K, V> implements Serializable {
  
      /**
       * Key of this <code>Pair</code>.
       */
      private K key;
  
      /**
       * Gets the key for this pair.
       *
       * @return key for this pair
       */
      public K getKey() {
          return key;
      }
  
      /**
       * Value of this this <code>Pair</code>.
       */
      private V value;
  
      /**
       * Gets the value for this pair.
       *
       * @return value for this pair
       */
      public V getValue() {
          return value;
      }
  
      /**
       * Creates a new pair
       *
       * @param key   The key for this pair
       * @param value The value to use for this pair
       */
      public Pair(K key, V value) {
          this.key = key;
          this.value = value;
      }
  
      /**
       * <p><code>String</code> representation of this
       * <code>Pair</code>.</p>
       *
       * <p>The default name/value delimiter '=' is always used.</p>
       *
       * @return <code>String</code> representation of this <code>Pair</code>
       */
      @Override
      public String toString() {
          return key + "=" + value;
      }
  
      /**
       * <p>Generate a hash code for this <code>Pair</code>.</p>
       *
       * <p>The hash code is calculated using both the name and
       * the value of the <code>Pair</code>.</p>
       *
       * @return hash code for this <code>Pair</code>
       */
      @Override
      public int hashCode() {
          // name's hashCode is multiplied by an arbitrary prime number (13)
          // in order to make sure there is a difference in the hashCode between
          // these two parameters:
          //  name: a  value: aa
          //  name: aa value: a
          return key.hashCode() * 13 + (value == null ? 0 : value.hashCode());
      }
  
      /**
       * <p>Test this <code>Pair</code> for equality with another
       * <code>Object</code>.</p>
       *
       * <p>If the <code>Object</code> to be tested is not a
       * <code>Pair</code> or is <code>null</code>, then this method
       * returns <code>false</code>.</p>
       *
       * <p>Two <code>Pair</code>s are considered equal if and only if
       * both the names and values are equal.</p>
       *
       * @param o the <code>Object</code> to test for
       *          equality with this <code>Pair</code>
       * @return <code>true</code> if the given <code>Object</code> is
       * equal to this <code>Pair</code> else <code>false</code>
       */
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o instanceof Pair) {
              Pair pair = (Pair) o;
              if (key != null ? !key.equals(pair.key) : pair.key != null) return false;
              if (value != null ? !value.equals(pair.value) : pair.value != null) return false;
              return true;
          }
          return false;
      }
  }