Tech notes 01 - Two Constructors in Java

I'm studying OOP using the Java How to Program Book. In exercise 4.19 - (Sales Commission Calculator) when I try to solve it. If we have two constructorswhen you call oneof them, JVMwill ignore the other one.
Check the pictures to know more.

1. case 1:

In the default constructor I just initialized

this.rate = 0.09;

variable, but I didn't use this constructorby the way!

2.case 2:

I did initialize

this.rate = 0.09;

with a non-zero value, if I didn't give it a value, the compiler will equal it to zero **
**Note: this is an opinion, I'm a student, if you have another answer for this case, please tell me! Thanks!