# Using Ternary Operator and Boolean

Hi,

I am trying to learn Java programming. A book I am reading asks that I create a program that will sum only the odd numbers from 1 to 1000. I am to use a Boolean variable and the ternary operator.

I have read a bit and researched the ternary operator, but am at a loss on how to use a boolean variable to get this information.

Can anyone give a suggestion?
Thanks,

• : Hi,
:
: I am trying to learn Java programming. A book I am reading asks that I create a program that will sum only the odd numbers from 1 to 1000. I am to use a Boolean variable and the ternary operator.
:
: I have read a bit and researched the ternary operator, but am at a loss on how to use a boolean variable to get this information.
:
: Can anyone give a suggestion?
: Thanks,
:

I guess it means something like this:
[code]
boolean isEven = (i % 2 == 0);
total += isEven ? 0 : i;
[/code]
This could be folded into one expression.

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[size=1](Its just my sig)

• : : Hi,
: :
: : I am trying to learn Java programming. A book I am reading asks that I create a program that will sum only the odd numbers from 1 to 1000. I am to use a Boolean variable and the ternary operator.
: :
: : I have read a bit and researched the ternary operator, but am at a loss on how to use a boolean variable to get this information.
: :
: : Can anyone give a suggestion?
: : Thanks,
: :
:
: I guess it means something like this:
: [code]
: boolean isEven = (i % 2 == 0);
: total += isEven ? 0 : i;
: [/code]
: This could be folded into one expression.
:
: ---------------------------------
: [size=1](Its just my sig)
:
:
Thank you. I will try that suggestion to see if it works as expected. By the way, is the word isEven a built-in method or something like that in Java? If so, can anyone tell me how I can find out what such built-in methods, keywords, classes are for Java?

I am used to VBA programming. In that language if there is a keyword like isEven it would be listed in the help file so you could find it. I looked in the index of the books I have on Java (one of them is called "Java J2SE: The Complete Reference") and can find no listing for isEven. Also, in VBA, when you type the period, you get a listing of methods or events that can be used. I am using a program called JEdit to create my Java programs, but this program gives no help at all on the keywords and such that I can use. Can anyone suggest a better way to create Java programs where I will actually get some help on the syntax of the Java language?

Thanks so much,
Anne
• [blue] By the way, is the word isEven a built-in method or something like that [/blue]

The modulus operator % gives the remainder of a division operation. If the remainder is 1 when divided by 2, then the integer is odd; otherwise it must be even.
[code]
public static boolean isEven(int n) {
return n % 2 == 0;
}
[/code]

I guess you could do it more efficiently using bitwise ops, but this is simpler to read and understand.

The javadoc libraries (on the http://java.sun.com site) are the documentation for the standard API calls. Language syntax references are also available. I recommend you follow some of the many tutorials on that site aswell.

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[size=1](Its just my sig)