Class SequencedCollectionsExamples

java.lang.Object

net.jrodolfo.java_evolution.java21.SequencedCollectionsExamples

public class SequencedCollectionsExamples
extends Object

Demonstrates sequenced collections, introduced in Java 21.

Java had many ordered collections before Java 21, but there was no shared API for first element, last element, or reversed views. Generic code had to know whether it was dealing with a List, deque, ordered set, or ordered map.

Sequenced collection interfaces give encounter-ordered data structures a common vocabulary. The reversed() operation returns a reversed view rather than requiring callers to make a defensive copy just to look at the same data from the other direction.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	SequencedCollectionsExamples.MapOrderSummary	Captures direct observations from SequencedMap.
static final record	SequencedCollectionsExamples.SequenceSummary	Captures direct observations from SequencedCollection.
static final record	SequencedCollectionsExamples.SequenceViewSummary	Captures the state of a collection and its reversed view after a mutation.

Constructor Summary

Constructors

Constructor	Description
SequencedCollectionsExamples()

Method Summary

Modifier and Type	Method	Description
SequencedCollectionsExamples.SequenceViewSummary	observeReversedView()	Observes that a reversed view is backed by its original collection.
SequencedCollectionsExamples.MapOrderSummary	summarizeMapOrder()	Uses first and last entry operations from SequencedMap.
SequencedCollectionsExamples.SequenceSummary	summarizeSequence(List<String> values)	Uses first, last, and reversed operations from SequencedCollection.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SequencedCollectionsExamples

public SequencedCollectionsExamples()

Method Details

summarizeSequence

public SequencedCollectionsExamples.SequenceSummary summarizeSequence(List<String> values)

Uses first, last, and reversed operations from SequencedCollection.

Parameters:

values - ordered values

Returns:

a summary of sequence operations

observeReversedView

public SequencedCollectionsExamples.SequenceViewSummary observeReversedView()

Observes that a reversed view is backed by its original collection.

Returns:

the original and reversed collections after changing the view

summarizeMapOrder

public SequencedCollectionsExamples.MapOrderSummary summarizeMapOrder()

Uses first and last entry operations from SequencedMap.

Returns:

a summary of map encounter order