Programming Forums > Application Development > Java

thechristelegacy · Feb 11th, 2008, 9:23 PM

How do I compare types in Java?

I'm doing input checking for the following code

          do {
			System.out.print("By how many px's would you like to increase(0 to 105):");
			increase = read.nextInt();
		} while ((increase < 0) || (increase > 105));

Currently it only checks if the input is between 0 and 105. Increase is declared as an Int and I want to add something to the while so that it would work something like

(Toggle Plain Text)

} while (((increase < 0) || (increase > 105)) || (typeof(increase) != typeof(Integer)));

Does this capability exists in Java? If not, is there an alternative method to complete the task?

Thanks for your time,
Anthony Christe

rhish.franks · Feb 11th, 2008, 9:47 PM

Can you elaborate yourself a bit more? But whatever you have given right now it can be solved by exception handeling. I am not a master of exception handeling but if you send those two inputs as arguements to a method, you can use IllegalArgumentException.

titaniumdecoy · Feb 11th, 2008, 10:55 PM

Assuming the increase variable in the code you posted is a Scanner, you can either use the hasNextInt() method to determine if the data waiting to be read can be interpreted as an int value, or catch an exception.

mrynit · Feb 12th, 2008, 12:59 AM

you mean making sure you dont add a float to an int? java will auto cast so it works as a float.

Fall Back Son · Feb 12th, 2008, 1:09 AM

the method getClass() will tell you the class.

rhish.franks · Feb 12th, 2008, 1:28 AM

but the main requirement is that to tell explicitely to user that the data entered by user for two different variables is not of same type. Implicite conversion will take place, but he wants that if types are not same the program should not go to evaluation sothere should not be any type casting.

pushkarajthorat · Feb 12th, 2008, 2:33 AM

you can do something:

increase.getClass().getName()

titaniumdecoy · Feb 12th, 2008, 2:25 PM

There is absolutely no reason to use getClass(). Scanner.nextInt() will either return an int or throw an exception. If you are reading that value into another type such as a float, that variable will be a float regardless of what the user enters.

pushkarajthorat · Feb 13th, 2008, 7:36 AM

You mis-located the change..

(Toggle Plain Text)

} while (((increase < 0) || (increase > 105)) || increase.getClass().getName().equals("java.lang.Integer);

itgalary · Feb 13th, 2008, 9:10 AM

Yeah i first thought instanceof can be used.

instanceof i think can be used for objects only.

Feb 11th, 2008, 9:23 PM	#1
thechristelegacy Expert Programmer Join Date: Jul 2004 Location: Somerset, Pa Posts: 708 Rep Power: 5	How to compare variable types in Java How do I compare types in Java? I'm doing input checking for the following code (Toggle Plain Text) do { System.out.print("By how many px's would you like to increase(0 to 105):"); increase = read.nextInt(); } while ((increase < 0) \|\| (increase > 105)); do { System.out.print("By how many px's would you like to increase(0 to 105):"); increase = read.nextInt(); } while ((increase < 0) \|\| (increase > 105)); Currently it only checks if the input is between 0 and 105. Increase is declared as an Int and I want to add something to the while so that it would work something like (Toggle Plain Text) } while (((increase < 0) \|\| (increase > 105)) \|\| (typeof(increase) != typeof(Integer))); } while (((increase < 0) \|\| (increase > 105)) \|\| (typeof(increase) != typeof(Integer))); Does this capability exists in Java? If not, is there an alternative method to complete the task? Thanks for your time, Anthony Christe Last edited by thechristelegacy; Feb 11th, 2008 at 9:26 PM. Reason: changes && to \|\|

Feb 11th, 2008, 9:47 PM	#2
rhish.franks Programmer Join Date: Feb 2008 Location: India Posts: 58 Rep Power: 1	Re: How to compare variable types in Java Can you elaborate yourself a bit more? But whatever you have given right now it can be solved by exception handeling. I am not a master of exception handeling but if you send those two inputs as arguements to a method, you can use IllegalArgumentException.

Feb 11th, 2008, 10:55 PM	#3
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: How to compare variable types in Java Assuming the increase variable in the code you posted is a Scanner, you can either use the hasNextInt() method to determine if the data waiting to be read can be interpreted as an int value, or catch an exception. Last edited by titaniumdecoy; Feb 11th, 2008 at 11:06 PM.

Feb 12th, 2008, 12:59 AM	#4
mrynit Hobbyist Programmer Join Date: Mar 2006 Location: WA, USA Posts: 332 Rep Power: 3	Re: How to compare variable types in Java you mean making sure you dont add a float to an int? java will auto cast so it works as a float. __________________ i dont know much about programming but i try to help

Feb 12th, 2008, 1:09 AM	#5
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 263 Rep Power: 2	Re: How to compare variable types in Java the method getClass() will tell you the class.

Feb 12th, 2008, 1:28 AM	#6
rhish.franks Programmer Join Date: Feb 2008 Location: India Posts: 58 Rep Power: 1	Re: How to compare variable types in Java but the main requirement is that to tell explicitely to user that the data entered by user for two different variables is not of same type. Implicite conversion will take place, but he wants that if types are not same the program should not go to evaluation sothere should not be any type casting.

Feb 12th, 2008, 2:33 AM	#7
pushkarajthorat Java Developer Join Date: Jun 2006 Location: Solapur, India. Posts: 24 Rep Power: 0	Re: How to compare variable types in Java you can do something: increase.getClass().getName() __________________ [Pushkaraj] Imagination is more important than knowledge � Albert Einstein

Feb 12th, 2008, 2:25 PM	#8
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: How to compare variable types in Java There is absolutely no reason to use getClass(). Scanner.nextInt() will either return an int or throw an exception. If you are reading that value into another type such as a float, that variable will be a float regardless of what the user enters.

Feb 13th, 2008, 7:36 AM	#9
pushkarajthorat Java Developer Join Date: Jun 2006 Location: Solapur, India. Posts: 24 Rep Power: 0	Re: How to compare variable types in Java You mis-located the change.. (Toggle Plain Text) } while (((increase < 0) \|\| (increase > 105)) \|\| increase.getClass().getName().equals("java.lang.Integer); } while (((increase < 0) \|\| (increase > 105)) \|\| increase.getClass().getName().equals("java.lang.Integer); __________________ [Pushkaraj] Imagination is more important than knowledge � Albert Einstein

Feb 13th, 2008, 9:10 AM	#10
itgalary Newbie Join Date: Feb 2008 Posts: 11 Rep Power: 0	Re: How to compare variable types in Java Yeah i first thought instanceof can be used. instanceof i think can be used for objects only. __________________ Free Programming help http://www.itgalary.com Free Revenue Sharing http://blog.itgalary.com Online Site seeing http://www.itgalary.com/maps/

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Programming Forums > Application Development > Java

How to compare variable types in Java