تحديات برمجيةالتحدي الثاني - حل التمرين الرابع بلغة جافا

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        
        Scanner input = new Scanner(System.in);
        String S1, S2, S3, S4="";

        System.out.print("Enter S1: ");
        S1 = input.nextLine();
        
        System.out.print("Enter S2: ");
        S2 = input.nextLine();
        
        System.out.print("Enter S3: ");
        S3 = input.nextLine();
        
        System.out.println("---------------------------------------");

        // Part 1
        System.out.println("The concatenation of S1 and S2 is equal S3? " + S3.equals(S1 + S2));

        // Part 2
        System.out.println("S1 is part of S2 or S1=S2? " + S2.contains(S1));

        // Part 3
        if (S1.length() > S2.length()) {
            S4 = S2 + S1;
        }

        // Part 4
        if (S2.length() > S1.length()) {
            S4 = S1 + S2;
        }

        // Part 5
        System.out.println("S2 is part of the second half of S1? " + (S1.indexOf(S2, S1.length() / 2) != -1));

        // Part 6
        System.out.print("The first half characters of S1 are: ");
        for (int i = 0; i < S1.length() / 2; i++) {
            System.out.print(S1.charAt(i));
        }
        
        System.out.println();
    }

}