How to concatenate the arrays at the end of the loop

I have created two class in Java. The main class 'Main' is used to pass array values into the second class 'Plan'. My code looks something like this:

import java.util.ArrayList;
import java.utils.Arras;

public class Main {

    public enum State {
        A,
        D,
        H
    };

    Plan[] plan= new Plan[] {
             new Plan(new State[]{State.A, State.A, State.A}),
             new Plan(new State[]{State.A, State.D, State.H})};
}

My other class 'Plan' looks like this:

import java.utils.Arrays;

public class Plan {

    public static Main.State[] input;
    public static Main.State[] output;
    public static Main.State[] input_new = new Main.State[4];

    this.input = input;
    this.output = output;
    this.input_new = input_new;

    for(int i = 0; i < input.length; i++) {
        input_new[i] = input[i];
    }
}

Now at the end of the loop I want to append the arrays so that it prints a single array which is

A A A A D H.

I tried using [this]/How can I concatenate two arrays in Java?) method, but it gives me an eeror saying 'ArrayUtils' cannot be resolved. Can somebody kindly point out my mistake here?

Thank you in advance.