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What is the keyword for modifiable method parameter in Java?

pascal_lalonde
on
Medium Priority
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Last Modified: 2012-05-07
Hello experts,

  An easy question from a newbie to Java. In C sharp, I use the keyword ref or out
when one method parameter is not a copy but the true object passed to the method.
How does it work in Java? PLease post a snippet of code.

Thank you!
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All method parameters come by reference,
unless those are simple values, then those are copies.
There is no keyword for it,
and a ReadOnly parameter doesn't exist in JAVA.

;JOOP!
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Top Expert 2016

Commented:
All method parameters are passed by *value*. There is no pass by reference in Java
If the parameter is a "primitive variable" (int, byte, long, basically any lowercase type) then Java automatically passes it by value. This cannot be changed.

If the parameter is a "object variable" (JFrame, Integer, basically any uppercase type) then Java automatically passes it by reference. This cannot be changed.

If you need to pass an integer by reference, you can make an object to wrap the integer around.
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Top Expert 2016

Commented:
>>then Java automatically passes it by reference. This cannot be changed.


It doesn't. It passes it by value. If it did, you *would* be able to change it - that's the definition of 'by reference'. It *is* a reference, but it's a copy of one.
Java Developer
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Top Expert 2010
Commented:
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Author

Commented:
CEHJ your answer is right but imcomplete. objects gave a complete answer and easy to understand for a newbie. I mentionned I am a newbie and that I wanted a snippet of code. Thank you both.
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Top Expert 2016

Commented:
pascal_lalonde, can you tell us why you ignored all comments there but one (part of which didn't even seem relevant)?

Author

Commented:
Hello CEHJ,

  I ignored the comments from sciuriware and Thomas4019 because they contain an error. No method parameters are passed by reference in Java. Then only your comments and those from object remain.
I indicated above how I discriminated between both of you. The answer if fully relevant anc complete.
I wanted to give points for a full answer not a partial and fast answer.

Regards.
Mick BarryJava Developer
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Top Expert 2010

Commented:
glad I could help :-)
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