Constructor object changes after declaration of constructor

Question

I have a BCD class with a constructor inside, and created a BCD object called 'b' from myArray. When I alter myArray, why does Java change b as well, and how do I make the two 'independent', like when I change myArray after the declaration, b stays constant?

public class BCD{
    private int digits;
    BCD(int[] digitArray){
        digits = digitsArray;
    public int nthDigit(int n) {
        return digits[n];
    }
    //more methods
   
    public static void main(String[] args) {
        int[] myArray = {1,2};
        BCD b = new BCD(myArray);
        myArray[1]=3;
        System.out.println(b.nthDigit(1));

}

BTW: `digitArray = digits;`cannot be correct, isn't it `digits = digitArray;`? (and assignment does not copy values inside the array, it just make left variable contain same object as right) — , Mar 05 '21 at 15:44
@user15244370 – Äh no, that's wrong, at least the second part of the sentence! Correct is: it just makes the left variable referring to the same object as that one on the right. — tquadrat, Mar 05 '21 at 15:48
@user15244370 – Sorry, but no! If you want to use "contain" with a variable, it is still the reference to an object that it contains, not the object itself. This lack of precision in wording it the reason for questions like this one! — tquadrat, Mar 05 '21 at 15:52

score 1 · Answer 1 · answered Mar 05 '21 at 15:47

1

Clone the array.

int[] a = {1,3};
int[] b = a.clone();
a[1]=33;
System.out.println(a[1]);
System.out.println(b[1]);

answered Mar 05 '21 at 15:47

the Hutt

16,980
2
14
44

score 0 · Answer 2 · answered Mar 05 '21 at 16:16

0

You passed a object reference to that constructor because of that all modification done to that object will be reflected to those holds reference of that object.

answered Mar 05 '21 at 16:16

Anand Kumar

156
7

Constructor object changes after declaration of constructor

2 Answers2