Testing string equality using hashCode()

java string hashcode
Andy picture Andy · Sep 23, 2009 · Viewed 24.5k times · Source

Is there any reason why a Java string cannot be tested for equality using it's hashCode method? So basically, instead of....

"hello".equals("hello")

You could use...

"hello".hashCode() == "hello".hashCode()

This would be useful because once a string has calculated it's hashcode then comparing a string would be as efficient as comparing an int as the string caches the hashcode and it is quite likely that the string is in the string pool anyway, if you designed it that way.

Answer

dstibbe picture dstibbe · Sep 23, 2009

because: hashCodes of two objects must be equal if the objects are equal, however, if two objects are unequal, the hashCode can still be equal.

(modified after comment)

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