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In<3b3b7ae2_1@dnews>, dnoyeB <lamont_gilbert@rigidsoftware.com> writes:


>"wallance" <wallance@sh.ctil.com> wrote in message news:3b3b1371_2@dnews...
>> hi,
>> i want to change a int type argument in java,what should i do?
>> for example:
>>
>> public func1(){
>>
>> int i = 10;
>> func2(i);
>> System.out.println(i)  ===> 11
>>
>> }
>> public func2(int arg){
>>     arg = arg + 1;
>> }
>>
>> i know in java your can trans a object .then it can modify by reference.
>> but this is int type,not object.what should i do?


>No you can not alter objects within functions.  AS in C and C++, passing a
>primitive OR object into a function always copies.  If its a primitive, you
>get a copied primitive, if its an object, you get a copied reference.
>Changing the copy does not affect the original.
>That way you never have to worry about passing around your references and
>getting them back null.  Again, the only context a value can be set to null
>is the context in which it was created.


 Erm, yes, this is a very :-( common question.   
 In Java everything is effectively a 32/64 bit word.
 If that is a number and you pass it into a method, 
 then a copy of the number arrives.

 Otherwise that will be a "reference" [probably just the address but 
 what does it matter to  you?]  to a class or array object.
 Pass it to a method, and what arrives is a FRESH COPY of the reference
 to the SAME OLD object referred.  


 The equivalent of having a reference to a number is....
 make it an array of one number, then it will be handled by reference.



 class MyClass inherits OldClass{
     public int method1(){
         int theAnswer[] = new [0]int;  // array of one ints                                   
         method2( theAnswer );          // numbered [0] to [0].
         ......
     }
     void method2( int refAnswer[]  ){
         refAnswer[0] = 99;
     }
 }

     







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