Question

02. Second Assignment – The FacebookUser Class

We’re going to make a small change to the UserAccount class from the last assignment by adding a new method:

public abstract void getPasswordHelp();

This method is abstract because different types of user accounts may provide different types of help, such as providing a password hint that was entered by the user when the account was created or initiating a process to reset the password. Next we will create a subclass of UserAccount called FacebookUser. The FacebookUser class needs to have the following fields and methods in addition to what is in UserAccount:

Fields:

String passwordHint

ArrayList<FacebookUser> friends

Methods:

void setPasswordHint(String hint) void friend(FacebookUser newFriend) void defriend(FacebookUser formerFriend) ArrayList<FacebookUser> getFriends()

The friend method should add the FacebookUser argument to the friends ArrayList (if that FacebookUser is already in the friends list, display an error message), and the defriend method should remove the FacebookUser argument from that ArrayList (if that FacebookUser is not in the friends list, display an error message). The getFriends method should return a copy of this user’s friends – create a new ArrayList with the same FacebookUsers in it as this user’s friends. Do not return the friends ArrayList directly, since this violates the principle of encapsulation. The getPasswordHelp method should display the passwordHint. The FacebookUser class should also implement the Comparable interface. FacebookUsers should be sorted alphabetically by username, ignoring capitalization. (Hint: notice that the toString method returns the username of the UserAccount.) Finally, write a driver program that creates several FacebookUsers and demonstrates the user of the setPasswordHint, friend, defriend, getFriends, and getPasswordHelp methods. Also, put the FacebookUser objects into an ArrayList, sort them (see the jar file for this topic for help on this), and print them out in sorted order.

You will be graded according to the following rubric (each item is worth one point):

• The UserAccount class is abstract and has the requested fields and methods
• The only abstract method is the getPasswordHelp method
• The FacebookUser class extends UserAccount
• FacebookUser has a friends ArrayList and methods to add, remove, and display the friends
• FacebookUser implements Comparable and sorts alphabetically on username, ignoring capitalization
• FacebookUser has a passwordHint that can be set through a method and is displayed by the getPasswordHelp method
• The driver program creates a list of FacebookUsers
• The driver program sorts and displays the lists of FacebookUsers
• The driver program exercises the setPasswordHint, friend, defriend, getFriends, and getPasswordHelp methods
• The program compiles and runs and the program is clearly written and follows standard coding conventions
• Note: If your program does not compile, you will receive a score of 0 on the entire assignment
• Note: If you program compiles but does not run, you will receive a score of 0 on the entire assignment
• Note: If your Eclipse project is not exported and uploaded to the eLearn drop box correctly, you will receive a score of 0 on the entire assignment
• Note: If you do not submit code that solves the problem for this particular assignment, you will not receive any points for the program’s compiling, the program’s running, or following standard coding conventions.

Here is my code

package calculator;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Calculator extends Application {
  
@Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));
  
Scene scene = new Scene(root);
  
stage.setScene(scene);
stage.show();
}

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
  
}

package calculator;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;

public class FXMLDocumentController implements Initializable {

private Double curr_num, end_res;
private String curr_operation;
Boolean res_oper=false;
@FXML
private TextField textToDisplay;

@Override
public void initialize(URL url, ResourceBundle rb) {

}

@FXML
private void handleDigitAction(ActionEvent event) {
if(res_oper){
textToDisplay.clear();
res_oper=false;
}
String digit = ((Button) event.getSource()).getText();
String oldText = textToDisplay.getText();
String newText = oldText + digit;
textToDisplay.setText(newText);
}

@FXML
private void handleOperationAction(ActionEvent event) {
String text = textToDisplay.getText();
Double digit = Double.parseDouble(text);
curr_num = digit;
curr_operation = ((Button) event.getSource()).getText();
textToDisplay.setText(curr_num + curr_operation);

}

@FXML
private void handleEqualOperation(ActionEvent event) {
Double val1,val2,res;
String val = textToDisplay.getText();
System.out.println(val);
if (val.contains("-")) {
String[] digits = val.split("-");
String digit1 = digits[0];
String digit2 = digits[1];
val1=Double.parseDouble(digit1);
val2=Double.parseDouble(digit2);
res=val1+val2;
textToDisplay.setText(res.toString());
}else if(val.contains("/")){
String[] digits = val.split("/");
String digit1 = digits[0];
String digit2 = digits[1];
val1=Double.parseDouble(digit1);
val2=Double.parseDouble(digit2);
res=val1-val2;
textToDisplay.setText(res.toString());
}else if(val.contains("X")){
String[] digits = val.split("X");
String digit1 = digits[0];
String digit2 = digits[1];
val1=Double.parseDouble(digit1);
val2=Double.parseDouble(digit2);
res=val1/val2;
textToDisplay.setText(res.toString());
}else if(val.contains("+")){
String[] digits = val.split("\\+");
String digit1 = digits[0];
String digit2 = digits[1];
val1=Double.parseDouble(digit1);
val2=Double.parseDouble(digit2);
res=val1*val2;
textToDisplay.setText(res.toString());
}
res_oper=true;

}

@FXML
private void handleClearAction(ActionEvent event) {
textToDisplay.clear();
}

@FXML
private void handleBackspaceAction(ActionEvent event) {
StringBuffer sb = new StringBuffer(textToDisplay.getText());
sb = sb.deleteCharAt(textToDisplay.getText().length()-1);
textToDisplay.setText(sb.toString());

}

}

Answer 1

DriverProgram.java

import java.util.ArrayList;
import java.util.Collections;

public class DriverProgram {

   public static void main(String[] args) {
       FacebookUser user1 = new FacebookUser("Walter White", "pa55");
       FacebookUser user2 = new FacebookUser("jesse Pinkman", "password");
       FacebookUser user3 = new FacebookUser("Daryl Dixon", "pas5");
       FacebookUser user4 = new FacebookUser("rick Grimes", "12345");
       System.out.println("\n");
      
       // create arrayList of FacebookUser then sort alphabetically ignoring case
       ArrayList<FacebookUser> users = new ArrayList<>();
       users.add(user1);
       users.add(user2);
       users.add(user3);
       users.add(user4);

       System.out.println("Users: ");
       for (FacebookUser faceBookUser : users) {
           System.out.println("\t" + faceBookUser);
       }

       System.out.println("\nSorting Users...\n");

       Collections.sort(users);

       System.out.println("Users: ");
       for (FacebookUser faceBookUser : users) {
           System.out.println("\t" + faceBookUser);
       }

       System.out.println("\n");
      
       // test setPasswordHint and getPasswordHelp methods
       user1.setPasswordHint("Thou shalt not pass");
       user1.getPasswordHelp();
       System.out.println(" ");
       user1.setPasswordHint("pwerd");
       user1.getPasswordHelp();
      
       //test friend method
       System.out.print("\n");
       System.out.println("***Test friend method***");
       user1.friend(user4);
       user1.friend(user3);
       user1.friend(user3);
       user1.friend(user2);
      
       //test defriend method
       System.out.print("\n");
       System.out.println("***Test defriend method***");
       user1.defriend(user2);
       user1.defriend(user2);

      
       //test getFriend method
       System.out.print("\n");
       System.out.println("***Test getFriend method***");
       user1.getFriends();

   }

}

FacebookUser.java

import java.util.ArrayList;

public class FacebookUser extends UserAccount implements
       Comparable<FacebookUser>, Cloneable {
   private String passwordHint;
   private ArrayList<FacebookUser> friends;

   public FacebookUser(String username, String password) {
       super(username, password);
       friends = new ArrayList<FacebookUser>();
   }

   public void setPasswordHint(String hint) {
       this.passwordHint = hint;
   }

   public void friend(FacebookUser newFriend) {
       if (friends.contains(newFriend)) {
           System.out.println("That friend has already been added. ");
       } else {
           friends.add(newFriend);
       }
   }

   public void defriend(FacebookUser formerFriend) {
       if (!friends.contains(formerFriend)) {
           System.out.println("That friend has not been added. ");
       } else {
           friends.remove(formerFriend);
       }
   }

   public ArrayList<FacebookUser> getFriends() {
       ArrayList<FacebookUser> friendsCopy = new ArrayList<FacebookUser>();
       for (FacebookUser user : this.friends) {
           try {
               friendsCopy.add((FacebookUser) user.clone());
           } catch (CloneNotSupportedException cloneNotSupportedException) {
               cloneNotSupportedException.printStackTrace();
           }
       }
       for (int i = 0; i < friendsCopy.size(); i++) {
           System.out.println(friendsCopy.get(i));
       }

       return friendsCopy;
   }

   @Override
   public int compareTo(FacebookUser o) {
       if (this.username.compareToIgnoreCase(o.username) != 0) {
           return this.username.compareToIgnoreCase(o.username);
       }

       return 0;
   }

   @Override
   public void getPasswordHelp() {
       setPasswordHint(passwordHint);
       System.out.println("Password Hint:\n" + passwordHint);

   }
}

UserAccount.java

public abstract class UserAccount {

   protected String username;
   protected String password;
   protected boolean active; // indicates whether or not the account is
                               // currently active

   public UserAccount(String username, String password) {
       this.username = username;
       this.password = password;
       active = true;
   }

   public boolean checkPassword(String password) {
       boolean passwordMatch;
       if (password.equals(this.password)) {
           passwordMatch = true;
       } else {
           passwordMatch = false;
       }
       return passwordMatch;
   }

   public void deactivateAccount() {
       active = false;
   }

   @Override
   public int hashCode() {
       final int prime = 31;
       int result = 1;
       result = prime * result
               + ((username == null) ? 0 : username.hashCode());
       return result;
   }

   @Override
   public boolean equals(Object obj) {
       if (this == obj)
           return true;
       if (obj == null)
           return false;
       if (getClass() != obj.getClass())
           return false;
       UserAccount other = (UserAccount) obj;
       if (username == null) {
           if (other.username != null)
               return false;
       } else if (!username.equals(other.username))
           return false;
       return true;
   }

   @Override
   public String toString() {
       return "Username: " + username + " ";
   }

   public abstract void getPasswordHelp();

} // end UserAccount