What is the reason for PMD CallSuperInConstructor?

Question

PMD defines the rule CallSuperInConstructor. What is the purpose of adding a no-argument call to super() in the constructor when it is not required by the compiler?

I realize I could disable the rule or use @SuppressWarnings to silence the rule in each class.

This question deals with why one should call super(...) in a constructor. My question is about why one would add a no-argument super() call when the compiler does not require it.

Answer 1

If your class

• has numerous overloaded constructors
• is extending a non-Object class which has numerous overloaded constructors

then when you explicitly call super() it avoids confusion which class/superclass constructor is called.

An example illustrating the above:

class Foo {
    final int x;
    Foo(int x) {
        this.x = x;
    }
    Foo() {
        this.x = 1;
    }
}

class Bar extends Foo {
    Bar(int x) {
    }
}

Question - what is the value of new Bar(10).x?