вроде все правильно
package com.javarush.task.pro.task05.task0504;
/*
Объединяем массивы
*/
public class Solution {
public static int[] firstArray = new int[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
public static int[] secondArray = new int[]{10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
public static int[] resultArray = new int[firstArray.length + secondArray.length];
public static void main(String[] args) {
int a = 0;
int b = 0;
for (int s = 0; s < (firstArray.length + secondArray.length - 1); s++) {
if (s < firstArray.length) {
resultArray[s] = firstArray[a];
a++;
}
if (s >=firstArray.length)
resultArray[s] = secondArray[b];
b++;
}
for (int i = 0; i < resultArray.length; i++) {
System.out.print(resultArray[i] + ", ");
}
}
}