Exercise 2.2

Exercise 2.3

Exercise 2.5

Exercise 2.6

public class Student {
}

public class LabClass{
}

Constructors:
TicketMachine

public int getTotal() { 
    return total;
} 

public void prompt() {
    System.out.println("Please insert the correct amount of money.");
}					 

public void showPrice() {
    System.out.println("The price of a ticket is " + price + " cents");
}				  

public TicketMachine()
{
    price = 1000;
    balance = 0;
    total = 0;
}				  

public void empty() {
    total = 0; 
}				  

public void setPrice(int newPrice) {
    price = newPrice;
}				 

public TicketMachine()
{
    price = 1000;
    balance = 0;
    total = 0;
}				 
	
public TicketMachine(int ticketCost)
{
    price = ticketCost;
    balance = 0;
    total = 0;
}				  

public int emptyMachine() {
    int oldTotal = total;
    total = 0;
    return oldTotal;
}				  

public void printTicket()
{
	int amountLeftToPay = price - balance;
	if(amountLeftToPay <= 0) {
		// Simulate the printing of a ticket.
		System.out.println("##################");
		System.out.println("# The BlueJ Line");
		System.out.println("# Ticket");
		System.out.println("# " + price + " cents.");
		System.out.println("##################");
		System.out.println();
	
		// Update the total collected with the price.
		total += price;
		// Reduce the balance by the prince.
		balance -= price;
	}
	else {
		System.out.println("You must insert at least: " +
						   amountLeftToPay + " more cents.");
				
	}
}				 

public Student(String fullName, String studentID)
{
	if(fullName.length() < 4) {
		System.out.println("Error! The name should be at least 4 characters long");
	}
	if(studentID.length() < 3) {
		System.out.println("Error! The studentID should be at least 3 characters long");
	}
	
	name = fullName;
	id = studentID;
	credits = 0;
}				

public String getLoginName()
{
	String loginNamePart;
	if(name.length() < 4) {
		loginNamePart = name;
	} else {
		loginNamePart = name.substring(0,4);
	}
	
	String loginIdPart;
	if(id.length() < 3) {
		loginIdPart = id;
	} else {
		loginIdPart = id.substring(0,3);
	}
	
	return  loginNamePart + loginIdPart ;
}				  

/**
 * Returns the author of this book.
 */
public String getAuthor() {
	return author;
}

/**
 *  Returns the title of this book.
 */
public String getTitle() {
	return title;
}			  

/**
 * Prints the name of the author in the terminal window.
 */
public void printAuthor() {
	System.out.println("Author: " + author);
}    

/**
 * Prints the title of the book in the terminal window.
 */
public void printTitle() {
	System.out.println("Title: " + title);
}				  

private int pages;

/**
 * Set the author and title fields when this object
 * is constructed.
 */
public Book(String bookAuthor, String bookTitle, int bookPages)
{
	author = bookAuthor;
	title = bookTitle;
	pages = bookPages;
}

/**
 * Returns the number of pages in this book.
 */
public int getPages() {
	return pages;
}				  

public void printDetails(){
	System.out.println("Title:  " + title);
	System.out.println("Author: " + author);
	System.out.println("Pages:  " + pages);
}				  

private String refNumber;

/**
 * Set the author and title fields when this object
 * is constructed.
 */
public Book(String bookAuthor, String bookTitle, int bookPages)
{
	author = bookAuthor;
	title = bookTitle;
	pages = bookPages;
	refNumber = "";
}

/**
 * Sets the reference number fot this book
 */
public void setRefNumber(String ref) {
	refNumber = ref;        
}

/**
 * Gets the reference number fot this book
 */
public String getRefNumber() {
	return refNumber;
}					

public void printDetails() {
	System.out.println("Title:  " + title);
	System.out.println("Author: " + author);
	System.out.println("Pages:  " + pages);
	
	String refNumberString; 
	if(refNumber.length() > 0 ) {
		refNumberString = refNumber;
	} else {
		refNumberString = "ZZZ";
	}
	System.out.println("Reference number:  " + refNumberString);        
}				  

public void setRefNumber(String ref) {
	if(ref.length() > 2) {
		refNumber = ref;     
	}
	else {
		System.out.println("Error! The reference number must be at least 3 characters long.");
	}
}				  

private int borrowed;
					

/** 
 * Borrows the book. Increments the number of times the book has been borrowed.
 */
public void borrow() {
	borrowed++;
}

/**
 * Gets the number of times the book has been borrowed.
 */
public int getBorrowed() {
	return borrowed;
}					

System.out.println("Borrowed: " + borrowed);

Exercise 2.53

public class Heater
{
    private int temperature;

    /**
    *  Creates a new Heater with an initial temperature of 15.
    */
	public Heater() {
		temperature = 15;
	}

	/**
	* Increases the temperature by 5 degrees
	*/ 
	public void warmer() {
		temperature += 5;
	}
	
	/**
	* Decreases the temperature by 5 degrees
	*/ 
	public void cooler() {
		temperature -= 5;
	}
	
	/**
	* Gets the current temperature of the heater
	*/
	public int getTemperature() {
		return temperature;
	}
}				

Exercise 2.52

public class Heater
{
    private int temperature;
    private int min;
    private int max;
    private int increment;
    
    
    /**
     *  Creates a new Heater with an initial temperature of 15.
     */
    public Heater(int minimum, int maximum) {
        min = minimum;
        max = maximum;
        temperature = 15;
        increment = 5;
    }
    
    /**
     * Increases the temperature
     */ 
    public void warmer() {
        int newTemperature = temperature + increment;
        if(newTemperature <= max) {
            temperature = newTemperature;
        }
    }
    
    /**
     * Decreases the temperature
     */ 
    public void cooler() {
        int newTemperature = temperature - increment;
        if(newTemperature >= min) {
            temperature = newTemperature;
        }
    }
    
    /**
     * Sets the increment, which determines how much the two methods 
     * warmer() and cooler() changes the temperature.
     */
    public void setIncrement(int inc)  {
        if(inc >= 0) {
            increment = inc;
        }
    }
    
    /**
     * Gets the current temperature of the heater
     */
    public int getTemperature() {
        return temperature;
    }
}