Question

I need to convert C code to Java.
The minimal C code is:

void changeX(int *x)
{
    *x=5;
}

changeX is called in function B as:

void B()
{
    int k= 2;
    changeX((int*) &k);
}

The problem while converting it into Java is that x is not a class member so i cannot use this. How can i convert such code to Java?

Answer 1

Assuming you’re really asking, “Can I use pass-by-reference in Java” (which that C code isn’t using, but is emulating with pointers, which also aren’t supported in Java) the answer is no.

Options:

• Pass in a reference to an object which does contain a field you can change
• (Ugly, but equivalent to the above in some senses) Pass in an array of size 1 constructed using the local variable, mutate the variable in the method, and then set the local variable again based on the array contents afterwards
• Return the new value and assign it that way
• Change your design so you don’t need this

The last two of these options are the nicest ones. If you could give more information about the bigger picture – why you think you want to do this – that would be helpful.