Calling a Java class to the main class for execution

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Andy - 07 Nov 2007 08:43 GMT

Say I have 2 files -

addition.java
negation.java

Now in the main class (say controlpanel.java) I want something like
this -

Print -" You want addition? Press 1"
" You want negation? Press 2"

then it should run addition.java when the user inputs 1 or negation if
the user inputs 2

Basically, the user will enter information (like a=1 and b=2 for a+b)
in addition.java (or negation.java) and not controlpanel.java

controlpanel.java is the main class to forward the user to a
particular class for operation. All these classes are under the same
Netbeans package.

How can this be done? This is basic and I couldn't figure it out :
( Switch statements were clueless about running classes from a main
class.

Thanks a lot!

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Sabine Dinis Blochberger - 07 Nov 2007 09:30 GMT

> Say I have 2 files -
>
[quoted text clipped - 3 lines]
> Now in the main class (say controlpanel.java) I want something like
> this -

Make all your classes part of a package.

> How can this be done? This is basic and I couldn't figure it out :
> ( Switch statements were clueless about running classes from a main
> class.

You don't "run" a class, you most usually instantiate it into an object.
Then you use the methods to do stuff.

You *can* use class methods without instantiating, but it depends on
your design.

> Thanks a lot!

Please refer to Suns Java tutorial to learn about classes and objects:
http://java.sun.com/docs/books/tutorial

specifically
http://java.sun.com/docs/books/tutorial/java/javaOO/index.html

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Sabine Dinis Blochberger

Op3racional
www.op3racional.eu

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Andrew Thompson - 07 Nov 2007 09:38 GMT

>Say I have 2 files -

"You have 2 files" OK.. getting back to being serious.

>addition.java
>negation.java

Class names in Java should be EachWordUpperCase,
so these class names should be Addition.java and
Subtraction.java rather than addition/subtraction or
addition/negation.

>Now in the main class (say controlpanel.java) I want something like
>this -
[quoted text clipped - 4 lines]
>then it should run addition.java when the user inputs 1 or negation if
>the user inputs 2

if (result==1) {
// call main constructor
Addition addition = new Addition();
} else {
Subtraction subtraction = new Subtraction();
}

>Basically, the user will enter information (like a=1 and b=2 for a+b)
>in addition.java (or negation.java) and not controlpanel.java

In that case, there is little reason to call the main methods
of the other classes, just construct and use the methods
they have from the (single) 'main' class.

>controlpanel.java is the main class to forward the user to a
>particular class for operation. All these classes are under the same
>Netbeans package.

So that means they are in the same Java package?
In that case, there will be no 'import's needed.

>How can this be done? This is basic and I couldn't figure it out :
>( Switch statements were clueless about running classes from a main
>class.

Huhh? What does that mean?
Are you referring to using a switch to select the
class to run? It could be done that way.

Signature

Andrew Thompson
http://www.athompson.info/andrew/

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Are Nybakk - 07 Nov 2007 11:47 GMT

> Say I have 2 files -
>
[quoted text clipped - 22 lines]
>
> Thanks a lot!

By creating objects?

Or did you mean loading compiled code (.class)? If so, look up
Class.forName(String)

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Calling a Java class to the main class for execution

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