Categories of Functional Interfaces and Predicate vs Function vs Supplier.

4 Main Categories:

1. Predicate: Takes one argument, returns boolean. (e.g., test(T t))
2. Function<T, R>: Takes one argument, returns a result. (e.g., apply(T t))
3. Supplier: Takes no argument, returns a result. (e.g., get())
4. Consumer: Takes one argument, returns nothing (void). (e.g., accept(T t))

Differences:

• Predicate: Used for filtering/logic checks.
• Function: Used for transforming data from one type to another.
• Supplier: Used for lazy generation of values.