Java: Appending to an array

In Java, arrays can't grow once they have been created; so, to add an element, you need to:
1. Create a new, larger array.

2. Copy over the content of the original array.
3. Insert the new element at the end.



# Copying the content
The `Arrays.copyOf` method can be used to make a copy of an array with a new size:
```java
Arrays.copyOf(originalArray, newSize)
```
The `newSize` argument can be larger or smaller than the size of the original array.

To append `40` to an array (`arr`),​ the code would be:

import java.util.Arrays;

class ArrayAppend {
    public static void main( String args[] ) {
      int[] arr = { 10, 20, 30 };
      System.out.println(Arrays.toString(arr));

      arr = Arrays.copyOf(arr, arr.length + 1);
      arr[arr.length - 1] = 40; // Assign 40 to the last element
      System.out.println(Arrays.toString(arr));
    }
}

In line $8$, a copy of `arr` is made with one extra slot. The new array is assigned to `arr`, replacing the original array.

# Apache Commons Lang
If you have [Commons Lang](https://commons.apache.org/proper/commons-lang/) on your classpath, you can use one of the [ArrayUtils.add](https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/ArrayUtils.html#add-int:A-int-) methods.

```java
int[] arr = { 10, 20, 30 };

arr = ArrayUtils.add(arr, 40);
```

Under the hood, `add` performs the same three steps described in the beginning. It just makes the process more readable.

How to append to an array in Java

Copying the content The Arrays.copyOf method can be used to make a copy of an array with a new size: Arrays.copyOf(originalArray, newSize)  The newSize argument can be larger or smaller than the size of the original array. To append 40 to an array (arr),​ the code would be: 