Programming Discrete Math Concepts for Beginners/

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Expanded Array Manipulation

Expanded Array Manipulation

Learn to manipulate arrays using an external library, an array of objects, and an array-based for loop.

We'll cover the following...

The ArrayUtils.addAll() method

When returning the array values, we individually access each index, which is a tremendous internal utility that’s able to iterate over the whole array. This was one of the utilities from an internal library. Consider the possibility of external libraries that are imported on demand and constantly updating. Apache Commons is an external library that helps us manipulate an array and has extensive utility for programmers.

The Array.getLength() method returns the length of the array. Here’s a code example:

import java.util.Arrays;
import java.lang.reflect.Array;
import org.apache.commons.lang3.ArrayUtils;

class Main{
    public static void main(String[] args){
        int[] numberCollection = {1, 2};
        //we can get a particular value through index
        System.out.println(Array.get(numberCollection, 1));
        //we can get the length of the array
        System.out.println(Array.getLength(numberCollection));
        int[] cartOne = {1, 2, 3, 4};
        System.out.println("The length of the first cart : " + cartOne.length);
        int[] cartTwo = {5, 200, 36, 4, 78, 123};
        System.out.println("The length of the second cart : " + cartTwo.length);
        int[] addingCart = ArrayUtils.addAll(cartOne, cartTwo);
        System.out.println("Combining two carts, the length has changed : " + addingCart.length);
        //we can also see the final output
        System.out.println("Adding the cart looks like this : " + Arrays.toString(addingCart));
    }
}
Finding the length of individual arrays and an array that's combined by the ArrayUtils.addAll() method

We get the following output when we run the code above:

2
2
The length of the first cart : 4
The length of the second cart : 6
Combining two carts, the length has changed : 10
Adding the cart looks like this : [1, 2, 3, 4, 5, 200, 36, 4, 78, 123]

In the code above:

  • Line 16: The ArrayUtils
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