Arrays.equals() / Arrays.toString() / Arrays.asList()

import java.util.Arrays;

// Compares the contents of two one-dimensional arrays.
Arrays.equals(a1, a2);

// Compares the contents of multidimensional (nested) arrays.
Arrays.deepEquals(a1, a2);

// Converts a one-dimensional array to a string.
Arrays.toString(array);

// Converts a multidimensional array to a string.
Arrays.deepToString(array);

// Converts an array to a fixed-size List.
Arrays.asList(T... a);

import java.util.Arrays;
import java.util.ArrayList;

// Use Arrays.equals() to compare array contents.
int[] a = {1, 2, 3};
int[] b = {1, 2, 3};
int[] c = {1, 2, 4};
System.out.println(Arrays.equals(a, b)); // Prints: true
System.out.println(Arrays.equals(a, c)); // Prints: false
System.out.println(a == b);              // Reference comparison, so prints: false

// Use Arrays.deepEquals() to compare two-dimensional arrays.
int[][] m1 = {{1, 2}, {3, 4}};
int[][] m2 = {{1, 2}, {3, 4}};
System.out.println(Arrays.deepEquals(m1, m2)); // Prints: true

// Use Arrays.toString() to display array contents for debugging.
int[] nums = {5, 1, 3, 2, 4};
System.out.println(Arrays.toString(nums)); // Prints: [5, 1, 3, 2, 4]

// Use Arrays.deepToString() to display a multidimensional array.
int[][] grid = {{1, 2, 3}, {4, 5, 6}};
System.out.println(Arrays.deepToString(grid)); // Prints: [[1, 2, 3], [4, 5, 6]]

// Use Arrays.asList() to convert to a List.
String[] arr = {"Java", "Python", "Swift"};
java.util.List<String> list = Arrays.asList(arr);
System.out.println(list); // Prints: [Java, Python, Swift]

// Convert to a resizable ArrayList.
ArrayList<String> mutableList = new ArrayList<>(Arrays.asList(arr));
mutableList.add("Go");
System.out.println(mutableList); // Prints: [Java, Python, Swift, Go]

Comparing arrays with == compares references, so even arrays with identical contents will return false. Always use Arrays.equals() to compare array contents.

Arrays.toString() is very handy for inspecting array contents during debugging. If you use Arrays.toString() on a multidimensional array (an array of arrays), the inner arrays are displayed as object references. Always use Arrays.deepToString() for multidimensional arrays.

To sort an array, use Arrays.sort(). To work with a List, see ArrayList's add() / get().