How to Efficiently Enlarge Arrays in Java?

Enlarging an Array in Java: Preserving Current Elements

Arrays in Java, unlike in other programming languages, are fixed in size. Adding new elements to a full array requires manual resizing or alternative data structures.

Resizing an Array

Due to Java's array immutability, resizing involves copying existing elements into a new array with the desired size. The java.lang.System.arraycopy(...) method can accomplish this task:

int[] oldArray = {1, 2, 3, 4, 5};
int[] newArray = new int[oldArray.length + 1]; // Larger array
System.arraycopy(oldArray, 0, newArray, 0, oldArray.length);

Alternative Data Structures

Another option is to employ dynamic data structures like java.util.ArrayList. Unlike arrays, ArrayLists can automatically enlarge themselves as elements are added:

ArrayList<integer> list = new ArrayList();
list.add(1);
list.add(2);
list.add(3);
// No resizing needed as the ArrayList expands dynamically</integer>

Using Arrays.copyOf(...)

Java 9 introduced the java.util.Arrays.copyOf(...) methods, which simplify array resizing:

int[] oldArray = {1, 2, 3, 4, 5};
int[] newArray = Arrays.copyOf(oldArray, oldArray.length + 1);

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