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Java Academy · Lesson

LinkedList vs ArrayList Trade-offs

Compare insertion, deletion, and random access performance to choose the right list type.

The Core Question

Both ArrayList and LinkedList implement List, so they share the same API. The difference lies in their internal data structures and the operations each performs efficiently.

ArrayList Internals

ArrayList stores elements in a contiguous array. When the array fills up, it is replaced with a new array 1.5× larger and all elements are copied.

import java.util.ArrayList;

ArrayList<String> list = new ArrayList<>(4); // initial capacity 4
list.add("A"); list.add("B"); list.add("C"); list.add("D");
list.add("E"); // triggers resize: new array of capacity 6

System.out.println(list.get(3)); // O(1) — direct index access

All lessons in this course

  1. LinkedList Internals
  2. Deque Operations: Stack and Queue
  3. LinkedList vs ArrayList Trade-offs
  4. PriorityQueue for Ordered Processing
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