> For the complete documentation index, see [llms.txt](https://www.pranaypourkar.co.in/the-programmers-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.pranaypourkar.co.in/the-programmers-guide/spring/utilities-and-libraries/apache-libraries/apache-commons-lang/arrayutils.md). # ArrayUtils ## About `ArrayUtils` is a utility class provided by **Apache Commons Lang** to simplify working with Java arrays. Java arrays are low-level and have limited built-in methods, making operations like searching, copying, checking for emptiness, or merging somewhat cumbersome. `ArrayUtils` provides **null-safe**, **convenient**, and **readable** methods to handle arrays of all primitive types and objects. It also helps avoid manual loops, `System.arraycopy`, and verbose boilerplate code. ## Characteristics * All methods are **static**. * Handles both **primitive** and **object** arrays. * Offers **null safety** — no need to check for `null` before calling utility methods. * Reduces common array operations to one-liners. ## Maven Dependency & Import ```xml org.apache.commons commons-lang3 3.12.0 ``` ```java import org.apache.commons.lang3.ArrayUtils; ``` ## Common Categories of Methods ### 1. Null and Empty Checks

Method	Description
`isEmpty(array)`	Returns `true` if array is `null` or length is 0
`isNotEmpty(array)`	Returns `true` if array is not `null` and has elements

**Example:** ```java if (ArrayUtils.isEmpty(myArray)) { // safely handle empty case } ``` ### 2. Array Creation and Conversion

Method	Description
`toObject(int[])`	Converts a primitive array to wrapper array
`toPrimitive(Integer[])`	Converts wrapper array to primitive array
`nullToEmpty(array)`	Converts `null` array to empty array

**Example:** ```java int[] ints = {1, 2, 3}; Integer[] boxed = ArrayUtils.toObject(ints); ``` ### 3. Element Checks | Method | Description | | --------------------------- | ------------------------------------------- | | `contains(array, value)` | Checks if array contains a specific element | | `indexOf(array, value)` | Returns the index of the element, or -1 | | `lastIndexOf(array, value)` | Returns the last index of the element | **Example:** ```java if (ArrayUtils.contains(new int[]{1, 2, 3}, 2)) { // element found } ``` ### 4. Adding and Removing Elements | Method | Description | | ----------------------------- | --------------------------------- | | `add(array, value)` | Adds value at the end | | `add(array, index, value)` | Inserts value at a specific index | | `remove(array, index)` | Removes value at index | | `removeElement(array, value)` | Removes first occurrence of value | **Example:** ```java int[] result = ArrayUtils.add(new int[]{1, 2}, 3); // [1, 2, 3] ``` ### 5. Concatenation and Cloning | Method | Description | | --------------------------------------- | ---------------------------- | | `addAll(array1, array2)` | Concatenates arrays | | `clone(array)` | Returns a clone of the array | | `subarray(array, startIndex, endIndex)` | Gets a range of elements | **Example:** ```java int[] combined = ArrayUtils.addAll(new int[]{1, 2}, new int[]{3, 4}); ``` ### 6. Array Reversal and Shuffling

Method	Description
`reverse(array)`	Reverses the array in place
`shuffle(array)`	Randomizes the order (not in standard `ArrayUtils`, but can use custom logic)

**Example:** ```java int[] nums = {1, 2, 3}; ArrayUtils.reverse(nums); // nums becomes {3, 2, 1} ``` ### 7. Equality and Comparison | Method | Description | | ------------------------------ | ------------------------------------------- | | `isSameLength(array1, array2)` | Checks if two arrays are of the same length | | `isEquals(array1, array2)` | Checks if all elements are equal | ### 8. Array Type Checking | Method | Description | | --------------------- | ----------------------------------------- | | `isArray(Object obj)` | Checks whether a given object is an array | ## Why Use `ArrayUtils` Instead of Raw Java?


Concern	Raw Java Approach	`ArrayUtils` Advantage
Null-safety	Manual checks	Built-in null checks
Adding/removing	Manual resizing or arraycopy	Simple one-liners
Searching	Manual loops	Ready-made methods
Conversion	Tedious type boxing/unboxing	Simplified conversions

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