can you not edit a double in a function with a argument?

Question

What is really wrong with this?

    public void changeElement(String isAdd, double Element, int timesBy, int lowCap) {
    ran = Math.floor(Math.random()*timesBy)+lowCap;
    if(isAdd == "+"){
        if((Element + ran) > 100){
            ran -= ((Element + ran)-100);
        };
        Element += ran;
    }else{
        if((Element - ran) < 0){
            ran -= (ran - Element); 
        };
        Element -= ran;
    };
    Elementi = (int)Element;
    ranI = (int)ran;

}

I know the math works because i changed the 'Element' tag to the double i have been using so why does it not change the true double like its meant to.

use `isAdd.equals("+")` not `==` – BatScream Nov 17 '14 at 23:56 — BatScream, Nov 17 '14 at 23:56
Java is pass by value. – Dawood ibn Kareem Nov 18 '14 at 00:21 — Dawood ibn Kareem, Nov 18 '14 at 00:21

score 0 · Accepted Answer · edited May 23 '17 at 11:49

0

I presume you mean it doesn't change the value of what you pass into the parameter?

If that's the case, Java is pass by value, not pass by reference.

In other words, rather than a reference of your parameter being passed to the method, a copy of the parameter is passed. Your method changes the copy but then once the method ends, the copy goes out of scope and is garbage collected.

So what's the solution?

Change the method signature to double and return Element. Then set Element to the return value when you call your function.

Please read this relevant answer as well.

edited May 23 '17 at 11:49

Community

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answered Nov 18 '14 at 00:17

Michael Goldstein

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"if" that's the case? – Dawood ibn Kareem Nov 18 '14 at 00:20
@DavidWallace I interpreted the question the best I could and answered it to the best of my ability. Is there something wrong with that? – Michael Goldstein Nov 18 '14 at 00:22
You got it right! thanks it works now. never thought of it like that. – GMYeti Nov 18 '14 at 01:42
@GavinMcLean glad to help Gavin. Keep on coding bro, it's a great occupation or hobby – Michael Goldstein Nov 18 '14 at 03:35

can you not edit a double in a function with a argument?

1 Answers1