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What is equivalent way of overloading a variable?

Posted on 2000-05-17
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Last Modified: 2012-05-04
If I want to reference a variable in one of two ways by the same name as if it were a type 'var'.  How would I do this in Java? e.g.

String var1 = "";
Object var1;

In this case I want to use var1 to either contain a string used to make a connection, or contain a reference to an object that refers to an already open connection.
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Question by:gary690774
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Laminamia063099 earned 80 total points
ID: 2817821
You are making a reference to the C/C++ union construct.  In Java there is no equivalent construct.  There is a Java solution.

The best way is to make you variable of type Object.  Then, if it contains a string it will act as a string, and if it contains a connection, it will act as a connection.

If you need to check which it is at a certain time, use the instanceOf operator:

var1 instanceOf String

will return true if it's currently a string.  Then you can cast it to a string to call string specific methods:

String newString = ((String)var1).substring(1);

If you have any more questions, or anything here doesn't work as described, drop a note and I'll help you out.

Laminamia :)
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by:imladris
ID: 2817826
There is no way to overload a variable. Would it work to build an object that does what you want? For instance a connection management class with methods that return the state (already open or not), another method to return the string used, and another method to return a connection object. There could also, instead or in addition, be a method that always returns a connection object. It would, if needed, make the connection with the string you mentioned, and then return a connection object.

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by:gary690774
ID: 2818066
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Author Comment

by:gary690774
ID: 2818067
Laminamia,

   This seems to be a very reasonable approach.  I thought that type Object had some applicability here, but I wasn't sure of how to use it. This seems better than creating a 'Variant' class.

Thanks,
Gary
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Author Comment

by:gary690774
ID: 2818072
Laminamia,

   This seems to be a very reasonable approach.  I thought that type Object had some applicability here, but I wasn't sure of how to use it. This seems better than creating a 'Variant' class.

Thanks,
Gary
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Expert Comment

by:Laminamia063099
ID: 2818540
Yup, It's a good way to relate objects.  Any time that you can use a common parent for the variable, use it.  If you can ever use a non-Object parent (i.e. some other common parent other than object) it's better too.

Good luck!

Laminamia :)
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