# Arrays — Core Java

Source: https://www.geekswithgeeks.com/en/core-java/java-arrays

> Create fixed-size 1-D and 2-D arrays, access elements safely within bounds, and use java.util.Arrays for sort, fill, copyOf and toString.

## Create & access

An array has a fixed `length` set at creation. Indexes are `0..length-1`; going outside throws `ArrayIndexOutOfBoundsException`.

```java
int[] a = new int[3];        // {0, 0, 0}
int[] b = {10, 20, 30};
b[1] = 99;
System.out.println(b.length); // 3

int[][] grid = new int[2][2]; // 2-D
```

## java.util.Arrays

The `Arrays` class has helpers: `sort`, `fill`, `copyOf`, `equals`, and `toString` (plain `println` on an array prints its hash-like form).

```java
int[] a = {3, 1, 2};
Arrays.sort(a);
System.out.println(Arrays.toString(a)); // [1, 2, 3]
```