Java - Explicit super() in subclass constructor

Question

I found some similar topics, for instance here, but they did not answer my question in entirely. Question is very simple:

Is it a good practice to call the super() in a subclass' constructor? I know of course, that if I do not make it explicitly, a compiler will do it for me, but I'm asking only in context of the best practices. Do you consider invoking super() in each subclass' constructor as a "triumph of form over substance" ?

I'm working with code which contains uses strategies, so I see, that for many programmers it does not matter at all... For me it does not matter as well now, but maybe I should change it...

You **have to** do it if the super class doesn't have a default constructor. For example: `class Fruit{ protected String flavor; public Fruit(String flavor) { this.flavor = flavor; } } class Apple extends Fruit { public Apple() { super("sweet"); } }`. Off topic: `super("sweet")` sounds funny :). — Luiggi Mendoza, Jun 10 '13 at 09:22
I never use the empty `super()` because it's simply redundant, but as @LuiggiMendoza says, `super(...)` can be necessary. — Vincent van der Weele, Jun 10 '13 at 09:23
Yes, of course. But I meant only the situation in which super can be omitted. — radekEm, Jun 10 '13 at 09:31

score 3 · Answer 1 · answered Jun 10 '13 at 09:25

Good practice? Call what's necessary to correctly initialize your object.

public class Foo {
    private String name;
    public Foo() { this(""); }
    public Foo(String n) { this.name = n; }
}

public class Bar extends Foo {
    private int x;
    public Bar(int y) { this("", y); }
    public Bar(String n, int y) {
        super(n);
        this.x = y;
    }
}

Evgeniy Dorofeev · Accepted Answer · 2013-06-10T09:44:06.877

3

In my opinion explicit super() call is just polluting the code. Default super() call is invented exactly for this purpose - to shorten the code. See SE library source, super() is hardly ever used, eg

public HashMap(int initialCapacity, float loadFactor) {
   if (initialCapacity < 0)
   ...

edited Jun 10 '13 at 09:44

answered Jun 10 '13 at 09:30

Evgeniy Dorofeev

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Java - Explicit super() in subclass constructor

2 Answers2