Java Arrays and ArrayLists

Arrays are fixed-size collections declared with a type and size. Elements are initialized to default values (0 for int, null for objects, false for boolean).

Array elements are accessed by zero-based integer index. The valid range is 0 to array.length - 1. Accessing an out-of-bounds index throws ArrayIndexOutOfBoundsException.

Visiting every element of an array using a loop. Standard for loops use an index variable; enhanced for-each loops iterate directly over elements.

A resizable collection from java.util that stores objects. Provides methods like add(), get(), set(), remove(), and size(). Requires import java.util.ArrayList.

Automatic conversion between primitive types and their wrapper classes (int <-> Integer, double <-> Double) when using ArrayLists, which cannot store primitives directly.

Arrays of arrays used to represent tabular or grid data. Accessed with two indices: row and column. Declared as type[][] name = new type[rows][cols].

A sequential search algorithm that checks each element of an array one by one until the target is found or the end is reached. Time complexity: O(n).

Arrays are fixed-size and can hold primitives or objects. ArrayLists are resizable but can only hold objects. Arrays use [] syntax; ArrayLists use method calls.

A simplified loop syntax that iterates over every element in an array or collection without using an index variable. Cannot modify the array or skip elements.