Concatinate [2] Arrays

import java.io.*;
import javax.swing.*;

/**
 * Create a function that add two input arrays with the same
 * number of elements but the output will be alternate letter
 * from both arrays.
 */
public class ConcatArrays {

    public ConcatArrays() throws IOException {
        char[] input1;
        char[] input2;

        do {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter for input1: ");
            input1 = br.readLine().toCharArray();

            System.out.print("Enter for input2: ");
            input2 = br.readLine().toCharArray();

            if (input1.length != input2.length) {
                System.out.println("No of elements not matched...");
            }
        } while (input1.length != input2.length);

        System.out.println("Output: " + alterCaseInput(input1, input2));
    }

    /**
     * Create an alternate case letter from two arrays.
     * <i>
     * Example: <br />
     * input1: <b>AAA<b/> <br />
     * input2: <b>BBB<b/> <br />
     * Output: <b>ABABAB</b>
     * </i>
     * @param input1 Array 1
     * @param input2 Array 2
     * @return Concatenated two arrays
     */
    private String alterCaseInput(char[] input1, char[] input2) {
        String output = "";
        int i = 0;
        while (true) {
            if (i < input1.length) {
                output += input1[i];
            }
            if (i < input2.length) {
                output += input2[i];
            }
            if (i >= input1.length && i >= input2.length) {
                break;
            }
            i++;
        }
        return output;
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    new ConcatArrays();
                } catch (IOException e) {
                    System.out.println("[WARNING] " + e.getLocalizedMessage());
                }
            }
        });
    }

}