switch statement on a java string : java, switch, string

you can use switch on int char and other primitive type.
String is not a primitive type, but Object type.

Bye, Giant.

08.04.2004 at 01:20AM PDT, ID: 11713132

wolfc:

Hehe, the workaround:

if(str.equals("A")) {
..
}
else if(str.equals("B")) {
..
}

The funny workaround (don't use this one):

switch(str.hashCode())
{
case 0x01234567:
..
break;
case 0x89abcdef:
..
break;
}

It will give you a switch in the code, but it won't work reliable.

08.04.2004 at 01:21AM PDT, ID: 11713136

Rank: Guru

In particular switch could be used with:
char, byte, short, int.

08.04.2004 at 01:21AM PDT, ID: 11713137

Rank: Sage

girionis:

If it is a one char string you coudl convert it to char and do it, otherwise there is no way as staed above.

08.04.2004 at 01:27AM PDT, ID: 11713176

I cant believe java is weak at this... one can easily do this in other languages like PHP for example!!
its hard to convince my manager who knows something about programming that one cant do a switch case on a string in java !!:)
I tried the .hashCode solution long time ago but thought it looks ugly with bad results too!

08.04.2004 at 01:29AM PDT, ID: 11713184

Rank: Guru

you can use a "simulated" switch statement:
if
else if
else if
else if
...

but I believe it's not really elegant.

Assisted Solution

08.04.2004 at 01:33AM PDT, ID: 11713200

Rank: Genius

zzynx:

>> is there away to do java switch statment on a string variable?
>> I know it can be done on integer but not strings.
Nice to answer your Q yourself. ;°)

>> any work around
First, what's wrong with the if/else if pair?

But if you really want one:

If you don't have too much strings you know beforehand,
you could make a unique link between the string and an integer by using a list:

List theList = new ArrayList();
theList.add("StringAtIndex0");
theList.add("StringAtIndex1");
theList.add("StringAtIndex2");
theList.add("StringAtIndex3");
...

String theString = "StringAtIndex2";
int index = theList.indexOf(theString);
switch(index) {
case 0: // means StringAtIndex0

break;

case 1: // means StringAtIndex1

break;

case 2: // means StringAtIndex2

break;

case 3: // means StringAtIndex3

break;

default :
break;
}

Accepted Solution

08.04.2004 at 01:36AM PDT, ID: 11713221

Rank: Master

armoghan:

Map strings to constant varibales of int type with names similar as Strings and use reflection to get them.

i.e. If you want to switch for
String s = "HELLO";
String s1 = "HELLO2";

create an integer like

const int HELLO=1;
const int HELLO2=2;

and so on

Then use the reflection to get the names of the variables according to the strings and use switch on them

:)

08.04.2004 at 01:37AM PDT, ID: 11713225

Rank: Genius

zzynx:

>> its hard to convince my manager who knows something about programming that one cant do a switch case on a string in java !!:)
Be glad you have one *who knows something about programming*. Most of them don't. ;°)

08.04.2004 at 01:41AM PDT, ID: 11713247

wolfc:

If you need to convince your manager:

Suppose a switch with an Object is possible would the case statements be equal when the reference is equal or when the content is equal?
If the reference should be equal the switch is useless. If the content should be equal which method should be used for that evaluation?
Either by implying the use of equals() (loosened semantics) or by allowing operator overloading.
PHP has loosened semantics, which leads to a kind of fuzzy logic in the code (the string is equal enough for me).
C++ has operator overloading, which leads to unreadable code (maybe == is properly overloaded, maybe not).

I like the Java solution, clear semantics, no operator overloading, can't switch on an Object.

Assisted Solution

08.04.2004 at 01:45AM PDT, ID: 11713265

Rank: Genius

And a switch is just a glorified if/else anyways

08.04.2004 at 01:48AM PDT, ID: 11713284

Rank: Genius

zzynx:

>> Then use the reflection
Think then you can better use a map to make the link between the Strings and the ints:

private final String STR_HELLO = "Hello";
private final String STR_WORLD = "World";
...

private final int INT_HELLO=1;
private final int INT_WORLD=2;
...

Map theMap = new HashMap();
theMap.put( STR_HELLO, new Integer(INT_HELLO) );
theMap.put( STR_WORLD, new Integer(INT_WORLD) );
...

String theString = .....;
int value = theMap.contains(theString) ? ((Integer)theMap.get(theString)).intValue() : -1;
switch (value) {
case INT_HELLO:
break;
case INT_WORLD:
break;
default:
break;
}

08.04.2004 at 01:51AM PDT, ID: 11713300

Rank: Guru

>And a switch is just a glorified if/else anyways
Full agree, as I posted before.

08.04.2004 at 01:52AM PDT, ID: 11713306

Rank: Genius

> Think then you can better use a map to make the link between the Strings and the ints:

though far simpler to just use an if/then/else

08.04.2004 at 01:58AM PDT, ID: 11713323

Rank: Genius

> its hard to convince my manager who knows something about programming that one cant do a switch case on a string in java

ask him under what situation you would need a switch, that could not be handled by an if/then/else statement

08.04.2004 at 02:10AM PDT, ID: 11713377

Rank: Guru

08.04.2004 at 02:12AM PDT, ID: 11713387

ok guys...
thanks alot for you comments... I think I got the answer I want. I wanted mainly to be sure and find a more elegant way of doing the coding. I have to split the points, which is not much anyways, I hope I did it right ... thanks to you all armoghan, girionis, wolfc, Giant2 and zzynx :)
Regards

08.04.2004 at 02:13AM PDT, ID: 11713400

Rank: Guru

krakatoa:

You could do something on these lines, but you'd have to watch for duplicate strings.

String st = "Hello";

byte[] b = st.getBytes();
int[] intt = new int[b.length];
int sum=0;

for(int a=0;a<b.length;a++){sum+=(int)b[a];}

System.out.println(sum);

switch (sum){

case (100):{}

}

08.04.2004 at 02:13AM PDT, ID: 11713401

and objects for sure :)

08.04.2004 at 02:16AM PDT, ID: 11713417

thank you krakatoa, but I think I will just stick with the original if else solution!

08.04.2004 at 02:16AM PDT, ID: 11713419

Rank: Genius