String comparison efficiency

[Alfredo Mesen]

I'm giving maintenance to someone elses sloppy code, on a servlet´s doPost it compares an input to determine the action that must be done, like


if (action.equals("delete")) {
...
}

so was wondering if doing

if (action.hashCode == new String("delete").hashCode())

was faster, or which method is better for comparing strings.

[Banfa]

I would be very surpised if using hashcodes was faster, you have so many more operations to perform

if (action.equals("delete")) {
...
}

Access each character for a comparison


if (action.hashCode == new String("delete").hashCode())

access each character to create a hashcode
allocate the memory for a new string
compare hashcodes

Ultimately it depends onb how fast your platform is at integer maths compared with how fast it is at integer comparison (leaving theString allocation out of the equation). I would thing the total operations to create and compare the hashcodes is greater than the total operations just to compare the string in the first place.

On the other hand if you are going to be comparing the string to "delete" several times it may be faster to use the has code. Also (of course) you can speed up the hashcode version by creating hashcodes for the strings when the program starts and storing it. Do this and the number of operations between the hashcode version and the straight comparison would be similar and they will go at about the same speed.

Of course you will run into trouble if a string ever occurs that is not "delete" but creates the same hash code.