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overriding object.equals java

Nice Narwhal answered on April 29, 2023 Popularity 6/10 Helpfulness 2/10

answer overriding object.equals java

overriding object.equals java

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Class Coordinate{
  double latitude;
  double longitude;
/**
  * Resource: https://www.technofundo.com/tech/java/equalhash.html
  * Overriding of the equals function in order for performing a
  * deep comparison involves the modification of the hash function.
  * 
  * Quote: "Note that it is generally necessary to override the hashCode
  * method whenever this method is overridden, so as to maintain the 
  * general contract for the hashCode method, which states that 
  * equal objects must have equal hash codes."
  *
  */
 // Using the object enables the function to be generic and thus can accept
  // any objects (Strings, Integers...) as parameter values
  @Override
  public boolean equals(Object obj)
		{
      // Comparison against itself should return true
			if(this == obj)
				return true;
      // comparison against null and some class class that is not 'itself'
			if((obj == null) || (obj.getClass() != this.getClass()))
			   return false;
      // typecast o to Coordinate so that we can compare data members
    // Without typecasting the program doesn't compile on some jdk's
    // setting the typecast - sets a promise to the compiler...
        Coordinate c = (Coordinate) obj;
         
        // Compare the data members and return accordingly
        return Double.compare(longitude, c.longitude) == 0
                && Double.compare(latitude, c.latitude) == 0;
    }
  /**
  * Overriding the hash function so that an
  * object with identical elements will have identical 
  * hash values
  */
  @Override
  public int hashCode()		
  {
			int hash = 7;
      //casting doubles to ints
      int intitude = (int) longitude;
      int intatude = (int) latitude;
      hash = 31 * hash + intitude;
			hash = 31 * hash +  intatude;
			return hash;
		}
}

Popularity 6/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java overriding

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Contributed on Apr 29 2023

Nice Narwhal

0 Answers Avg Quality 2/10

overriding object.equals java

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