Default constructors in Java

Question

I know I\'m asking some serious 101 question here...

I have some class Foo and a class Bar that extends Foo. In Foo

Answer 1

If parameters are not required and/or have default values then you can define default constructor (without parameters):

class Foo
{
    public final int DEFAULT_A = 42;
    protected int a;
    protected int b;

    public Foo(final int a, final int b)
    {
        this.a = a;
        this.b = b;
    }

    // Is equal to new Foo(Foo.DEFAULT_A, 0);
    public Foo()
    {
        this.a = this.DEFAULT_A;
    }

}

class Bar extends Foo {}

class PiBar extends Bar
{
    public final int DEFAULT_A = Math.PI;

}