switch statement on String in Java

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duckman

Re: switch statement on String in Java

#11

Dec 10th, 2006

I repeat: You CAN'T use Strings.
So you MUST use either Enums or integer literals.

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Re: switch statement on String in Java

#12

Dec 13th, 2006

where did u find your sampl about switches on mathematical operation?

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Re: switch statement on String in Java

#13

Dec 13th, 2006

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Originally Posted by jwenting

I repeat: You CAN'T use Strings.
So you MUST use either Enums or integer literals.

Well, of course you can't use Strings directly, but with the use of default enum mappings you can get nearly exactly the same thing. Looking at this:

http://www.xefer.com/2006/12/switchonstring

Enum.valueOf() is using a hash map to lookup values by the actual name of the enum, so effectively this is doing what any other language that supports switches on string is doing under the hood.

This is certainly better than using a cascade of if/else statements or ginning up a hash implementation from scratch.

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Re: switch statement on String in Java

#14

Dec 14th, 2006

Well I think what you can do is you can use string operation on your input to get such a Switch Case Statement

For Example if you want to go for Black, blue or something else.....what you can do is you make user enter string and find the alphabet position where every string has a different Char

For Example

Black
Blue
Here if you take out 3rd char and Put Switch Case statement for 3rd Char

Case 'c':
Means Input was Black

Case 'u':
Means input string was Blue...

I think it can be done in this way but I am not sure ....Can anyone tell me is it possible or not

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Re: switch statement on String in Java

#15

Dec 14th, 2006

i can help u! Just leaving m know i can assist u later. ok . fine?

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Re: switch statement on String in Java

#16

Dec 28th, 2006

Only way I know how to emulate a switch on strings, and this has already been mentioned without example code, is like the following:

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 java Syntax (Toggle Plain Text) 
void StringSwitch (String str) {
	if (str == null) { /* If the String is null... */ }
	else if (str.equals ("Some Possibility")) { /* ... */ }
	else if (str.equals ("Another Possibility")) { /* ... */ }
	else if (str.equals ("Possibility # 3")) { /* ... */ }
	// Etc, etc, etc
	else { /* DEFAULT Operation */ }
}
void StringSwitch (String str) {
	if (str == null) { /* If the String is null... */ }
	else if (str.equals ("Some Possibility")) { /* ... */ }
	else if (str.equals ("Another Possibility")) { /* ... */ }
	else if (str.equals ("Possibility # 3")) { /* ... */ }
	// Etc, etc, etc
	else { /* DEFAULT Operation */ }
}

Keep in mind that the checks are all performed, in order, until a match is made. With large "switch" statements, the more common values should be placed near the beginning, and less common values can come near the end of the if-else statements. That'll speed up code execution, because common values won't have to be checked against dozens of not-so-common values before a match is found.

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duckman

Re: switch statement on String in Java

#17

Dec 29th, 2006

That's not a switch at all, it's just a massive if-else statement pushed into a method (not a bad idea per se) that you called "switch".

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