02. Password

import java.util.Scanner;

public class Password {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        String password = scanner.nextLine();
        String input = "";

        while (true) {
            input = scanner.nextLine();
            if (input.equals(password)) {
                System.out.println("Welcome " + username + '!');
                break;
            }
        }
    }
}

ИЛИ:

import java.util.Scanner;

public class Password {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        String password = scanner.nextLine();
        String input = scanner.nextLine();

        while(!input.equals(password)){
            input = scanner.nextLine();
        }

        System.out.println("Welcome " + username + '!');
    }
}

ИЛИ:

import java.util.Scanner;

public class Password {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        String password = scanner.nextLine();
        String input = "";

        while(!(input = scanner.nextLine()).equals(password)){
        }

        System.out.println("Welcome " + username + '!');
    }
}