Java - Instance variable is dependent on Constructor argument

Question

I want to set a variable which is dependent on the argument passed to the constructor. At the moment my code looks something like this. Is calling a method here bad practice and is there a better way of doing this? I have searched for an answer but haven't been able to find anything. All help appreciated.

public class Test {
    int num;

    public Test(int num) {
        this.num = prime(num);
    }

    public int prime(int num) {
        //code to get a prime number
    }   
}

You should write class names with a capital Letter. – keuleJ Nov 29 '19 at 19:31 — keuleJ, Nov 29 '19 at 19:31

keuleJ · Answer 1 · 2019-12-10T07:07:44.340

2

Calling a method from constructor is bad practice if it is an overridable method. With overridable methods you get into initialisation order troubles. See this question.

You should make your prime() method private, static or final.

edited Dec 10 '19 at 07:07

answered Nov 29 '19 at 19:30

keuleJ

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I never thought of that, but it is right, of course. – keuleJ Nov 29 '19 at 19:36
2

Or make the method `final`. – mypetlion Nov 29 '19 at 19:55
1

The key element why static is better than private or final: a static method can't ever use any of the fields of that class. This you avoid all the potential issues from accessing non static fields prior those being initialized! – GhostCat Nov 29 '19 at 20:20
Yeah that was the original way I did it – MR_P Nov 29 '19 at 23:11

Java - Instance variable is dependent on Constructor argument

1 Answers1