Refernces, pointer and variables in Java

Question

I usually program in python and C, so this world of java confuses me quite a bit.

I am looking for a way to make my code more elegant, and in these other languages I would do it by passing by reference (or with pointers, depending on the language), the variable.

At one point in the code, I repeat a piece of code several times because each one depends on a certain previous situation. In summary, it could be understood that I want to modify several variables with the same code block, for which I first want to select the variable that I want to modify, assign it a "nickname", and then work with the nickname but modify the original variable.

So i want to change this

if (condition){
    if (condition){
        //modify var1
    } else {
        //modify var2
    }
}else if (condition){
    if (condition){
        //modify var1
    } else {
        //modify var2
    }
}

for something like this

if (condition){
    nickname = var1;
} else {
    nickname = var2;
}

if (condition){
    // modify nickname
}else if (condition){
    // modify nickname
}

Is there a way to do this in Java? Or am I condemned (using this aproach) to have redundant code?

In C i could do something like

// nickname as pointer from type of var1 and var2
if (condition){
    nickname = &var1;
} else {
    nickname = &var2;
}

// Work over nickname

Could you show an equivalent of this in C or Python? I don't understand what you want from the description. Or some pseudocode is also fine. — akuzminykh
– akuzminykh, Commented Mar 9, 2021 at 20:16
You cannot pass references like in C. But in this case, you can extract the code to a method, return var1 or var2 and assign the method's return value to nickname. — f1sh
– f1sh, Commented Mar 9, 2021 at 20:17
@f1sh I get that, butI would prefer that when altering to "nickname", the variable to which it had been linked had already been changed — bench
– bench, Commented Mar 9, 2021 at 20:28

Jim Garrison · Accepted Answer · 2021-03-09 20:27:53Z

1

Given

if (condition){
    nickname = var1;
} else {
    nickname = var2;
}

This works ONLY if var1 and var2 are:

References to object instances (i.e. not primitive values)
Mutable, i.e. have internal state that can be changed (String is immutable)
Type-compatible with each other. nickname must be assignable from both var1 and var2

In that case you can use nickname to modify the internal state of a referenced object.

answered Mar 9, 2021 at 20:27

Jim Garrison

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4 Comments

bench Over a year ago

Thank you, unfortunately this ends my search. I am working with String.

ETO Over a year ago

@bench The strings are immutable in java. So no matter how many references you have, you won't be able to modify them.

akuzminykh Over a year ago

@bench Is your question actually answered at this point? I worry that you might think: "Changing a bunch of characters in Java is impossible.".

bench Over a year ago

This probably won't fix it, you're right @akuzminykh. Is there any way to do something like this but with Strings. In my code I am concatenating them, so i know that i can modify theme, but I create several variables that store things that will behave in a similar way, that is why I am looking for this behavior but for Strings.

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