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Overriding hashCode()

 
Saathvik Reddy
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Hi Ranchers,

I am overriding the equals() method of the object.
Example:
Class Blah
{
public abstract String getOid();
public boolean equals(Object o)
{
return this.getOid().equals(((Blah)o).getOid());
}
}
I assume If the oid's of the two classes are equal then the two objects are equal.
I read that its a best practice to override hashCode() method when you override equals() method and it should return the same hashCode if two objects are equal.
What should be the implementation for the hashCode() method?

Thanks in advance
 
Keith Lynn
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If oid is a String, you can return its hashCode.
 
Saathvik Reddy
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How does it Guarantee the hashCode() method returns same hashCode for two objects?
 
Saathvik Reddy
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If the object equals() doesnt simply depend on oid and is more complex then how to implement it?
 
Keith Lynn
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An efficient way would be to return the same hashCode every time.

But to make it more efficient, you would need to, depending on what makes the two objects equal, make sure the hashCodes are the same if the objects are equal.
 
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