Java has existing collections that implements the stack data type. Why is it important to know how to implement our own stack data types?

What will be an ideal response?

The existing stack data types may not support design decisions that are necessary for your application. By
knowing how to write your own stack data type, you can customize it to meet your particular needs. It is also important to
understand how the existing data types work, as this gives you in-depth understanding of some of the design issues that were
faced and decisions that were made, both of which you may experience if you have to create your own stack data type.