simple program tokenizer problem

[tgraves]

I get errors targetting the ' that I use for each case. I tried using nothing and also quotes in their place, but no luck. Whats the problem.

If this isn't the place to get help with programs, please point me in the right direction.

import java.util.StringTokenizer;

class Birthday {
public static void main(String[] arguments) {
StringTokenizer st1;
String birthday = "09/08/1900";
st1 = new StringTokenizer(birthday, "/");
String month = st1.nextToken();
switch (month) {
case '01':
month = "January";
break;
case '02':
month = "February";
break;
case '03':
month = "March";
break;
case '04':
month = "April";
break;
case '05':
month = "May";
break;
case '06':
month = "June";
break;
case '07':
month = "July";
break;
case '08':
month = "August";
break;
case '09':
month = "September";
break;
case '10':
month = "October";
break;
case '11':
month = "November";
break;
case '12':
month = "December";
break;
}

String day = st1.nextToken();
String year = st1.nextToken();

System.out.println("The month is " + month);
System.out.println("The day is " + day);
System.out.println("The year is " + year);
}
}

[red_evolve]

Greetings.
If I am not mistaken, the target in the switch statement works for Integers only.
Java experts, please correct me if I'm wrong.
You could use If statements instead if switch doesn't work.

import java.util.StringTokenizer;

class Birthday 
{
     public static void main(String[] arguments) 
     {
          StringTokenizer st1;
          String birthday = "09/08/1900";
          st1 = new StringTokenizer(birthday, "/");
          String month = st1.nextToken();
 
          if(month=="01")
               month = "January";
          else if(month=="02")
               month = "February";
          else if(month=="03")
               month = "March";
          else if(month== "04")
               month = "April";

          else if(month== "05")
               month = "May";
          else if(month== "06")
               month = "June";
          else if(month== "07")
               month = "July";
          else if(month== "08")
               month = "August";
          else if(month== "09")
               month = "September";
          else if(month== "10")
               month = "October";
          else if(month== "11")
               month = "November";
          else if(month== "12")
               month = "December";

          String day = st1.nextToken();
          String year = st1.nextToken();

          System.out.println("The month is " + month);
          System.out.println("The day is " + day); 
          System.out.println("The year is " + year);
     }
}

I think that should work. ;)

[tgraves]

Greetings. If I am not mistaken, the target in the switch statement works for Integers only. Java experts, please correct me if I'm wrong. You could use If statements instead if switch doesn't work.

I think that should work. ;)

Thanks. Well I know If statements would work, but I really want to figure out whats wrong with the switch, so I dont have the same problem with another program.
:)

A better question I need answering is

When should I use "==" instead of "="?

The book I'm reading doesn't explain this one clearly.

I do understand that using && prevents the right side of the If statement from being run if the left side is not true.

[red_evolve]

Greetings.
LOL, I see. That's good. I mean, you have the inquisitiveness to explore although you know of a way which would work.

Well, "==" differs from "=" as in:-
-> "=" is used for evaluating an expression (arithmetic).
-> "==" would always evaluate to a Boolean value, either True or False.

So, I would make it easy that, "==" is used in determining the Truth of an expression. You want to test whether something is equal to something. I.e. Is 'a' equal to 5? If yes, do something.

if (a==5)
   // do something

I hope you get what I mean. :D Not really good at explaining things.
And, about the "&&" operator, yeah, it's true.
If the left hand side is false, it will never evaluate the right hand side because due to the nature of AND operator, one false, all false right? So, if there is one expression that you would deem important and must be evaluated, put it on the left hand side.
However, I kinda remember something from my Programming Language Concept class some time back that, this differs in some programming languages.

[tgraves]

Thank you for your help. More questions to come when I find time to learn more. :)

[red_evolve]

Greetings.
No problem! ;)

[gusano79]

... the target in the switch statement works for Integers only. ...

An expression in aswitch statement can be any of these: int, short, byte, or char. red_evolve is basically correct, though, since they're all integer types under the hood.

--sg

[gusano79]

... And, about the "&&" operator, yeah, it's true. If the left hand side is false, it will never evaluate the right hand side ... this differs in some programming languages.

With some languages, it may depend on the compiler as well. Shortcutting an operation like that can be considered an optimization; I've heard of compilers (can't think of any off the top of my head though) that stop evaluating the expression if the LHS is false when optimizations are turned on, but will evaluate everything when they're turned off... this is especially frustrating when the debug build (optimization off) works fine, but the release build (optimization on) doesn't.

You're save with Java, though; the shortcut is written into the language specification.

--sg

[gusano79]

Another way to approach your switch statement is to convert the string to a number first, then use the number in the switch. The Integer class can do this.

--sg