More Lists

Grocery List:

adds items to the END of the list
"removes" all items at once

        
	        ______        
	       |      |
 numberOfItems |      |    MAX_SIZE  ________
               |______|
 _______________________
|                       |
|     GROCERY LIST      |
|                       |
|_______________________|
|                       |                
|_______________________|
|                       |
|_______________________|
|                       |                
|_______________________|
|                       |
|_______________________|
|                       |                
|_______________________|
|                       |
|_______________________|
|                       |                
|_______________________|

Simple Answering Machine:

adds phone messages to the END of the list
"removes" phone messages from the END of the list

The Computer Science term for this kind of list is a "stack". It is analogous to a "stack of cafeteria trays" where trays are added to the top of the stack and taken from the top of the stack.

                ______        
	       |      |
 numberOfItems |      |    MAX_SIZE  ________
               |______|
 _______________________________________________________
|                                                       |
|                    ANSWERING MACHINE                  |
|_______________________________________________________|
|                               |                       |
|           Message             |      Date / Time      |
|_______________________________|_______________________|
|                               |                       |               
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |               
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |               
|_______________________________|_______________________|

Phone Message Class
import java.util.*;

 public class PhoneMessage {
 
   private String message;
   
   private Date dateTime;
   
   public PhoneMessage(String message) {
   
     this.message = message;
     dateTime = new Date();
   }
   
   public String toString() {
   
     String s = "";
     
     s += dateTime.toString() + " ";
     
     s += message;
     
     return s;
   }
}
 











Answering Machine Class
public class AnsweringMachine {

  private final int MAX_SIZE = 10;
  private int numberOfMessages;
  private PhoneMessage[] messages;
  
  public AnsweringMachine() {
    numberOfMessages = 0;
    messages = new PhoneMessage[MAX_SIZE];
  }
  
  public boolean addMessage(String message) {
  
    if (numberOfMessages < messages.length) {
      
      messages[numberOfMessages] = 
                 new PhoneMessage(message);
      
      numberOfMessages++;
      
      return true;
    }
    
    else
      
      return false;
  }
  
  public String lastMessage() {
    if (numberOfMessages > 0) {
      
      PhoneMessage pm = messages[numberOfMessages - 1];
      
      numberOfMessages--;
      
      return pm.toString();
    }
    else
      
      return "No messages";
  }
  
  public int numberOfMessages() {
    return numberOfMessages;
  }
  
  public boolean hasMessages() {
    if (numberOfMessages > 0)
      return true;
    else
      return false;
  }
  
  public String toString() {
  
    String s = "";
    for (int i = 0; i < numberOfMessages; i++)
      s += messages[i].toString() + "\n";
    return s;
  }
  
  public static void main(String[] args) {
  
    AnsweringMachine machine = new AnsweringMachine();
    
    System.out.println("Message: " + machine.lastMessage());
    
    System.out.println("\nMessages: " + machine);
    
    machine.addMessage("Call home");
    
    if(!machine.addMessage("Doctor appt. tomorrow at 9:00"))
      System.out.println("Message NOT added");
    
    if (!machine.addMessage("Party tonight on Brent Road"))
      System.out.println("Message NOT added");
    
    System.out.println("\nYou have " + 
                       machine.numberOfMessages() +
		       " messages");
    
    System.out.println("\nMessages: \n" + machine);
    
    System.out.println("\nMessage: " + 
                       machine.lastMessage());
    System.out.println("\nMessages: \n" + machine);
    
    System.out.println("\nHave messages?: " + 
                        machine.hasMessages());
    System.out.println("\nMessage: " + 
                       machine.lastMessage());
    System.out.println("\nMessage: " + 
                       machine.lastMessage());
    System.out.println("\nMessage: " + 
                       machine.lastMessage());
  }
}
/*OUTPUT:
csc% java AnsweringMachine
eos% java AnsweringMachine
Message: No messages

Messages: 

You have 3 messages

Messages: 
Sat Apr 19 13:46:08 EDT 2003 Call home
Sat Apr 19 13:46:08 EDT 2003 Doctor appt. tomorrow at 9:00
Sat Apr 19 13:46:08 EDT 2003 Party tonight on Brent Road


Message: Sat Apr 19 13:46:08 EDT 2003 Party tonight on Brent Road

Messages: 
Sat Apr 19 13:46:08 EDT 2003 Call home
Sat Apr 19 13:46:08 EDT 2003 Doctor appt. tomorrow at 9:00


Have messages?: true

Message: Sat Apr 19 13:46:08 EDT 2003 Doctor appt. tomorrow at 9:00

Message: Sat Apr 19 13:46:08 EDT 2003 Call home

Message: No messages

*/     


Waiting Room List: 

 adds new patients to the END of the list
 removes patients from the FRONT of the list

The Computer Science term for this kind of list is a "queue".
It is analogous to the "queue (line) in a cafeteria" where courteous people add
themselves to the end of the line and the person at the front of the line is served
first.
        
	        ______        
	       |      |
 numberOfItems |      |    MAX_SIZE  ________
               |______|
 _______________________________________________________
|                                                       |
|                      WAITING ROOM LIST                |
|_______________________________________________________|
|                               |                       |
|             Name              |      Symptoms         |
|_______________________________|_______________________|
|                               |                       |               
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |
|_______________________________|_______________________|
|                               |                       |                
|_______________________________|_______________________|
|                               |                       |               
|_______________________________|_______________________|


Patient Class
public class Patient {

  private String name;
  
  private String symptoms;
  
  public Patient(String name, String symptoms) {
  
    this.name = name;
    this.symptoms = symptoms;
  }
  
  public String toString() {
  
    return name + "\t" + symptoms;
  }
}


Waiting Room List Class
 public class WaitingRoomList {

   private int numberOfPatients;
   
   private Patient[] patients;
   

   public WaitingRoomList(int size) {
   
     patients = new Patient[size];
     
     numberOfPatients = 0;
   }
   
   public int numberOfPatients() {
   
     return numberOfPatients;
   }
   
   public boolean addPatient(String name, String symptoms) {
   
     if (numberOfPatients < patients.length) {
     
       patients[numberOfPatients++] = 
                               new Patient(name, symptoms);
       
       return true;
     }
     return false;
   }
   
   public String removePatient() {
   
     if (numberOfPatients > 0) {
     
       //Get first patient's name and symptoms
       String patientInfo = patients[0].toString();
       
       //Shift the rest of the patients up one spot 
       //(left shift)
       for (int i = 0; i < numberOfPatients - 1; i++)
       
         patients[i] = patients[i+1];
	 
       //Decrement number of patients
       numberOfPatients--;
       
       //Return first patient's name and symptoms
       return patientInfo;
     }
     
     else
     
       return "No patients";
  }
 
  public String toString() {
  
    String s = "";
    for (int i = 0; i < numberOfPatients; i++)
      s += (i+1) + ". " + patients[i].toString() + "\n";
    return s;
  }
  
  public static void main(String[] args) {
  
    WaitingRoomList list = new WaitingRoomList(5);
    
    if (!list.addPatient("Britney Spears", "laryngitis"))
      System.out.println("Patient NOT added");
      
    if (!list.addPatient("Kurt Vonnegut", "writer's cramp"))
      System.out.println("Patient NOT added");
      
    if (!list.addPatient("Joseph Smith", "stomach flu"))
      System.out.println("Patient NOT added");
      
    
    System.out.println("\nPatients: \n" + list);
    
    int numberOfPatients = list.numberOfPatients();
    
    for (int i = 0; i < numberOfPatients; i++)
      System.out.println("Patient: " + list.removePatient()); 
      
    System.out.println("Patient: " + list.removePatient());
  }
}
/* PROGRAM OUTPUT:
eos% java WaitingRoomList

Patients: 
1. Britney Spears	laryngitis
2. Kurt Vonnegut	writer's cramp
3. Joseph Smith	stomach flu

Patient: Britney Spears	laryngitis
Patient: Kurt Vonnegut	writer's cramp
Patient: Joseph Smith	stomach flu
Patient: No patients
*/

More Lists

Grocery List:

adds items to the END of the list
"removes" all items at once

adds items to the END of the list
"removes" all items at once

"removes" all items at once

______ | | numberOfItems | | MAX_SIZE || _____ | | | GROCERY LIST | | | |_| | | |_| | | |_| | | |_| | | |_| | | |_| | | |_| | | |_____________|

Simple Answering Machine:

adds phone messages to the END of the list
"removes" phone messages from the END of the list

adds phone messages to the END of the list
"removes" phone messages from the END of the list

"removes" phone messages from the END of the list

The Computer Science term for this kind of list is a "stack". It is analogous to a "stack of cafeteria trays" where trays are added to the top of the stack and taken from the top of the stack.

Phone Message Class

import java.util.*; public class PhoneMessage { private String message; private Date dateTime; public PhoneMessage(String message) { this.message = message; dateTime = new Date(); } public String toString() { String s = ""; s += dateTime.toString() + " "; s += message; return s; } }

Answering Machine Class

Waiting Room List:

adds new patients to the END of the list
removes patients from the FRONT of the list

adds new patients to the END of the list
removes patients from the FRONT of the list

removes patients from the FRONT of the list

The Computer Science term for this kind of list is a "queue". It is analogous to the "queue (line) in a cafeteria" where courteous people add themselves to the end of the line and the person at the front of the line is served first.

______ | | numberOfItems | | MAX_SIZE || _____________ | | | WAITING ROOM LIST | |_| | | | | Name | Symptoms | |_|_| | | | |_________|_| | | | |_________|_| | | | |_________|_| | | | |_________|_| | | | |_________|_| | | | |_________|_| | | | |_________|_| | | | |_|___|

Patient Class

public class Patient { private String name; private String symptoms; public Patient(String name, String symptoms) { this.name = name; this.symptoms = symptoms; } public String toString() { return name + "\t" + symptoms; } }

Waiting Room List Class

More Lists

Grocery List: adds items to the END of the list "removes" all items at once

adds items to the END of the list "removes" all items at once

"removes" all items at once

Simple Answering Machine: adds phone messages to the END of the list "removes" phone messages from the END of the list

adds phone messages to the END of the list "removes" phone messages from the END of the list

"removes" phone messages from the END of the list

The Computer Science term for this kind of list is a "stack". It is analogous to a "stack of cafeteria trays" where trays are added to the top of the stack and taken from the top of the stack.

Phone Message Class

import java.util.*; public class PhoneMessage { private String message; private Date dateTime; public PhoneMessage(String message) { this.message = message; dateTime = new Date(); } public String toString() { String s = ""; s += dateTime.toString() + " "; s += message; return s; } }

Answering Machine Class

Waiting Room List: adds new patients to the END of the list removes patients from the FRONT of the list

adds new patients to the END of the list removes patients from the FRONT of the list

removes patients from the FRONT of the list

The Computer Science term for this kind of list is a "queue". It is analogous to the "queue (line) in a cafeteria" where courteous people add themselves to the end of the line and the person at the front of the line is served first.

Patient Class

public class Patient { private String name; private String symptoms; public Patient(String name, String symptoms) { this.name = name; this.symptoms = symptoms; } public String toString() { return name + "\t" + symptoms; } }

Waiting Room List Class

Grocery List:

adds items to the END of the list
"removes" all items at once

adds items to the END of the list
"removes" all items at once

Simple Answering Machine:

adds phone messages to the END of the list
"removes" phone messages from the END of the list

adds phone messages to the END of the list
"removes" phone messages from the END of the list

Waiting Room List:

adds new patients to the END of the list
removes patients from the FRONT of the list

adds new patients to the END of the list
removes patients from the FRONT of the list