---
id: kb-2026-00126
title: Array Data Structure
schema_type: TechArticle
category: computer-science
language: en
confidence: high
last_verified: '2026-06-02'
created_date: '2026-05-22'
generation_method: ai_structured
ai_models:
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data_period: static
atomic_facts:
  - id: fact-computer-science-01
    statement: 'The Java Language Specification defines arrays as objects whose components contain values of the array component type.'
    source_title: Chapter 10. Arrays
    source_url: https://docs.oracle.com/javase/specs/jls/se21/html/jls-10.html
  - id: fact-computer-science-001
    statement: 'The Java Language Specification states that array components are referenced by integer indices from 0 to n - 1, where n is the array length.'
    source_title: Chapter 10. Arrays
    source_url: https://docs.oracle.com/javase/specs/jls/se21/html/jls-10.html
  - id: fact-computer-science-002
    statement: 'The Java SE API describes ArrayList as a resizable-array implementation of the List interface.'
    source_title: ArrayList (Java SE 21 & JDK 21)
    source_url: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/ArrayList.html
completeness: 0.88
known_gaps: []
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primary_sources:
  - title: Chapter 10. Arrays
    type: language_specification
    year: 2023
    url: https://docs.oracle.com/javase/specs/jls/se21/html/jls-10.html
    institution: Oracle
  - title: ArrayList (Java SE 21 & JDK 21)
    type: api_documentation
    year: 2023
    url: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/ArrayList.html
    institution: Oracle
secondary_sources: []
---

## TL;DR

An array is an indexed collection whose elements are accessed by integer positions. Java's ArrayList is a standard-library example of a resizable-array implementation.

## Core Explanation

Arrays are one of the most common ways to represent ordered collections because an element can be referred to by its integer index. Language specifications define the exact indexing and element-type rules for a given language. Dynamic arrays or resizable-array implementations add growth behavior on top of the indexed collection idea.

## Further Reading

- [Java Language Specification: Arrays](https://docs.oracle.com/javase/specs/jls/se21/html/jls-10.html)
- [Java SE API: ArrayList](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/ArrayList.html)

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