public class UserService {

  private UserRepository userRepository;

  public UserService(UserRepository userRepository) {
    this.userRepository = userRepository;
  }

  public User getUserById(long id) {
    try {
      return userRepository.getUserById(id);
    } catch (Exception e) {
      // Log the exception here
      System.out.println("An error occurred while fetching the user: " + e.getMessage());
      return null;
    }
  }
}

public class UserRepository {

  public User getUserById(long id) throws Exception {
    // Database query to fetch the user
    if (id < 0) {
      throw new Exception("Invalid user id");
    }
    // Return the user object
    return new User(id, "John Doe");
  }
}

public class User {

  private long id;
  private String name;

  public User(long id, String name) {
    this.id = id;
    this.name = name;
  }

  public long getId() {
    return id;
  }

  public String getName() {
    return name;
  }
}

public class Main {
  public static void main(String[] args) {
    System.out.println("Hello World");
  }
}

class main {

public static boolean findDuplicates(int[] nums) {
        for(int i = 0; i < nums.length; i++) {
            for(int j = 0; j < i; j++) {
                if(nums[i] == nums[j]) {
                   return true;
                }
            } 
        }
        return false;
}


    public static void main(String[] args) {

        int[] myArray = {1,3};

        System.out.println(findDuplicates(myArray));

    }

}

public static String addBinary(){
 // The two input Strings, containing the binary representation of the two values:
    String input0 = "1010";
    String input1 = "10";

    // Use as radix 2 because it's binary    
    int number0 = Integer.parseInt(input0, 2);
    int number1 = Integer.parseInt(input1, 2);

    int sum = number0 + number1;
    return Integer.toBinaryString(sum); //returns the answer as a binary value;
}

import javax.mail.*;
import javax.mail.internet.*;
import java.util.*;
 
public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException
{
    boolean debug = false;
 
     //Set the host smtp address
     Properties props = new Properties();
     props.put("mail.smtp.host", "smtp.example.com");
 
    // create some properties and get the default Session
    Session session = Session.getDefaultInstance(props, null);
    session.setDebug(debug);
 
    // create a message
    Message msg = new MimeMessage(session);
 
    // set the from and to address
    InternetAddress addressFrom = new InternetAddress(from);
    msg.setFrom(addressFrom);
 
    InternetAddress[] addressTo = new InternetAddress[recipients.length]; 
    for (int i = 0; i < recipients.length; i++)
    {
        addressTo[i] = new InternetAddress(recipients[i]);
    }
    msg.setRecipients(Message.RecipientType.TO, addressTo);
    
 
    // Optional : You can also set your custom headers in the Email if you Want
    msg.addHeader("MyHeaderName", "myHeaderValue");
 
    // Setting the Subject and Content Type
    msg.setSubject(subject);
    msg.setContent(message, "text/plain");
    Transport.send(msg);
}

public class Factorial
{
	public static void main(String[] args)
	{	final int NUM_FACTS = 100;
		for(int i = 0; i < NUM_FACTS; i++)
			System.out.println( i + "! is " + factorial(i));
	}
	
	public static int factorial(int n)
	{	int result = 1;
		for(int i = 2; i <= n; i++)
			result *= i;
		return result;
	}
}