G4G0-1/Semester 1/Programming 1/Week 2/Week 2 Programming - Objects and Classes.md

Lecture 1 (11:00)

• Class is a template
• Object is the product of a class
• Classes have attributes / fields, and methods, which can have parameters
  • Attributes are shared between all instances of the class
  • Methods are executable code, which change depending on the parameters given
• Extra information = argument

Lecture 2 (13:00)

Types

• System.out.println()- print line function

void changeColor(String newColor)

• newColor is a parameter, of type String
• A parameter receives the argument

void withdraw(int amount)

• amount is a parameter with type integer, holding a whole number
• withdraw is a method

void withdraw()

int getBalance()

• void type means a method does not return a value / returns a null value
• int type means a method returns an integer type

public int getBalance()
{
	return balance;
}

• Empty () tells the compiler that getBalance is a method and not an integer variable
• return balance; passes the integer value of the variable balance as the result of the method. if balance is 200, x.getBalance() would result in 200 as an integer.
• Return type must always be included in method header.

Bank Account Class

public class Account
{
    // Account Balance
    private int balance;
    private int overdraftLimit;

    /**
     * Constructor for objects of class Account
     */
    public Account()
    {
        // initialise account balance
        balance = 10;
        overdraftLimit = -100;
        cash = 0;
    }

    /** 
     * @param  no parameter needed
     * @return     the balance
     */
    public int getBalance()
    {
        // put your code here
        return balance;
    }
    
    /**
     * Display current overdraft limit
     */
    public int getOverdraft()
    {
        return overdraftLimit;
    }
    
    /**
     * Set a new overdraft limit, overwriting with @newOverdraftLimit
     */
    public void modifyOverdraft( int newOverdraftLimit )
    {
        overdraftLimit = newOverdraftLimit;
        System.out.println( "Your overdraft limit is now £" + newOverdraftLimit );
    }
    
    /**
     * Deposit @amount into the account
     */
    public void doDeposit( int amount )
    {
        balance = balance + amount;
        System.out.println( "Your account has been credited with £" + amount + ". Your balance is now £" + balance );
    }
    
    /**
     * If withdraw amount is less than total usable balance, allow withdraw
     * Else reject and show balance
     */
    public void withdraw( int amount ) 
    {
	    private int cash;
        if( overdraftLimit < ( balance - amount ))
        {
            balance = balance - amount;
            cash = amount;
            System.out.println( "You have withdrawn £" + cash );
        }
        else 
        {
            System.out.println( "Not enough balance to withdraw. Your balance is: £" + balance );
        }
    }
}