18 February 2022

Schrödinger's Cat

Schroedinger's Cat

$$i\hbar{\partial\Psi\over \partial t} = -{\hbar^2\over 2m} \nabla^2\Psi + V\Psi.$$

Java has a Schrödinger's Cat: Optonal<T> This represents an object that might or might not be present.

Friends These are the primitive "friend" types for Optional<T>

OptionalInt
OptionalDouble
OptionalLong

More About Streams

Sources

Collections, using stream()
Arrays, using Arrays.stream()
BufferedReaders, using lines()
String, using chars() yields an IntStream

Intermediate Operations All of these return streams. They are chainable.

Terminal Operations Purportedly, you want to do something with the stream you generate. In fact, nothing happens until one of these operations is invoked.

count() Counts the items in the stream.
sum() Sum the items in a numerical stream.
boolean allMatch(Predicate<? super T>) Returns true if all items match the predicate.
boolean anyMatch(Predicate<? super T>) Returns true if any of the items match the predicate.
Optional<T> findAny(Predicate<T>) Returns an Optional containing some elemenet for which the the predicate is true, and returns and empty Optional otherwise.
Optional<T> findFirst(Predicate<T>) Returns an Optional containing the first elemenet for which the the predicate is true, and returns and empty Optional otherwise.