利用TreeSet集合的特性(去重、有序)即可

import java.util.Scanner;
import java.util.TreeSet;

/**
 * 【整型数组合并】
 *
 */
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        TreeSet<Integer> treeSet = new TreeSet<>();

        int lengthOne = sc.nextInt();
        for (int i = 0; i < lengthOne; i++) {
            treeSet.add(sc.nextInt());
        }

        int lengthTwo = sc.nextInt();
        for (int i = 0; i < lengthTwo; i++) {
            treeSet.add(sc.nextInt());
        }
        
        for (Integer integer : treeSet) {
            System.out.print(integer);
        }
    }
}