Added simple OOP sample code.

35 files changed, 627 insertions, 0 deletions

diff --git a/oop/01-account/.gitignore b/oop/01-account/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/01-account/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/01-account/Account.java b/oop/01-account/Account.java
new file mode 100644
index 0000000..03a9e9c
--- /dev/null
+++ b/oop/01-account/Account.java
@@ -0,0 +1,26 @@
+
+public class Account {
+	
+	/* Declaring fields  - represent state */
+	
+	int accountNumber;
+	double balance;
+	
+	
+	/* Declaring methods - represent operations */
+	
+	public void withdraw(double amount) {
+		if (balance >= amount) {
+			balance = balance - amount;
+		}
+	}
+
+	public void deposit(double amount) {
+		balance += amount;
+	}
+	
+	public double getBalance() {
+		return balance;
+	}
+	
+}
diff --git a/oop/01-account/AccountTest.java b/oop/01-account/AccountTest.java
new file mode 100644
index 0000000..0409d86
--- /dev/null
+++ b/oop/01-account/AccountTest.java
@@ -0,0 +1,23 @@
+
+public class AccountTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Account a1 = new Account(); // Instantiation of 'Account' class
+		Account a2 = new Account();
+		
+		System.out.println(a1.getBalance());
+		
+		a1.deposit(100.0);
+		System.out.println(a1.getBalance());
+		
+		a1.withdraw(50.0);
+		System.out.println(a1.getBalance());
+		
+		a2.deposit(100.0);
+		System.out.println(a2.getBalance());
+	}
+
+}
diff --git a/oop/02-non-static-methods/.gitignore b/oop/02-non-static-methods/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/02-non-static-methods/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/02-non-static-methods/Calculator.java b/oop/02-non-static-methods/Calculator.java
new file mode 100644
index 0000000..ecc7234
--- /dev/null
+++ b/oop/02-non-static-methods/Calculator.java
@@ -0,0 +1,15 @@
+
+public class Calculator {
+	
+	public int add(int a, int b) {
+		return a + b;
+	}
+	
+	public int subtract(int a, int b) {
+		return a - b;
+	}
+	
+	public double convertFromC2F(double cTemp) {
+		return cTemp*180/100 + 32.0;
+	}
+}
diff --git a/oop/02-non-static-methods/MyApp.java b/oop/02-non-static-methods/MyApp.java
new file mode 100644
index 0000000..2ebdcae
--- /dev/null
+++ b/oop/02-non-static-methods/MyApp.java
@@ -0,0 +1,13 @@
+
+public class MyApp {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Calculator cal = new Calculator();
+		
+		System.out.println(cal.convertFromC2F(100.0));
+	}
+
+}
diff --git a/oop/03-static-methods/.gitignore b/oop/03-static-methods/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/03-static-methods/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/03-static-methods/Calculator.java b/oop/03-static-methods/Calculator.java
new file mode 100644
index 0000000..7ec2851
--- /dev/null
+++ b/oop/03-static-methods/Calculator.java
@@ -0,0 +1,29 @@
+
+public class Calculator {
+	public static int x; // static (class) field
+	public int y; // instance field
+	
+	public static int add(int a, int b) { // static (class) method
+		return a + b;
+	}
+	
+	public static int subtract(int a, int b) {  // static (class) method
+		return a - b;
+	}
+	
+	public static double convertFromC2F(double cTemp) {  // static (class) method
+		return cTemp*180/100 + 32.0;
+	}
+	
+	public void setY(int y) { // instance method
+		this.y = y;
+	}
+	
+	public int getXxY() { // instance method
+		return x * y;
+	}
+	
+//	public static int getXxY2() {
+//		return x * y;
+//	}
+}
diff --git a/oop/03-static-methods/MyApp.java b/oop/03-static-methods/MyApp.java
new file mode 100644
index 0000000..0137433
--- /dev/null
+++ b/oop/03-static-methods/MyApp.java
@@ -0,0 +1,25 @@
+
+public class MyApp {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		System.out.println(Calculator.convertFromC2F(100.0));
+		
+		Calculator.x = 5;
+		
+		Calculator cal1 = new Calculator();
+		cal1.setY(10);
+		System.out.println(cal1.getXxY()); // prints 50
+		
+		Calculator cal2 = new Calculator();
+		cal2.setY(11);
+		
+		Calculator.x = 6;
+		
+		System.out.println(cal1.getXxY()); // 60
+		System.out.println(cal2.getXxY()); // 66
+	}
+
+}
diff --git a/oop/04-constructors/.gitignore b/oop/04-constructors/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/04-constructors/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/04-constructors/Account.java b/oop/04-constructors/Account.java
new file mode 100644
index 0000000..82875be
--- /dev/null
+++ b/oop/04-constructors/Account.java
@@ -0,0 +1,47 @@
+
+public class Account {
+	
+	/* Declaring fields  - represent state */
+	
+	int accountNumber;
+	double balance;
+	
+	// No argument constructor
+	public Account() {
+		System.out.println("No argument constructor");
+	}
+	
+	// A constructor with an argument
+	public Account(double initialBalance) {
+		balance = initialBalance;
+		System.out.println("Argument constructor");
+	}
+	
+	/* Declaring methods - represent operations */
+	
+	public void withdraw(double amount) {
+		if (balance >= amount) {
+			balance = balance - amount;
+		}
+	}
+
+	// Overloaded method
+	public void deposit(double amount) {
+		balance += amount;
+	}
+	
+	// Overloaded method
+	public void deposit(int amount) {
+		balance += amount;
+	}
+
+	
+	public double getBalance() {
+		return balance;
+	}
+	
+	
+//	public int getBalance() {
+//		return 1;
+//	}
+}
diff --git a/oop/04-constructors/AccountTest.java b/oop/04-constructors/AccountTest.java
new file mode 100644
index 0000000..9774e84
--- /dev/null
+++ b/oop/04-constructors/AccountTest.java
@@ -0,0 +1,23 @@
+
+public class AccountTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Account a1 = new Account(); // Instantiation of 'Account' class
+		Account a2 = new Account(10.0);
+		
+		System.out.println(a1.getBalance());
+		
+		a1.deposit(100.0);
+		System.out.println(a1.getBalance());
+		
+		a1.withdraw(50.0);
+		System.out.println(a1.getBalance());
+		
+		a2.deposit(100.0);
+		System.out.println(a2.getBalance());
+	}
+
+}
diff --git a/oop/05-destructor/.gitignore b/oop/05-destructor/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/05-destructor/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/05-destructor/Account.java b/oop/05-destructor/Account.java
new file mode 100644
index 0000000..a5baab7
--- /dev/null
+++ b/oop/05-destructor/Account.java
@@ -0,0 +1,33 @@
+
+public class Account {
+	
+	/* Declaring fields  - represent state */
+	
+	int accountNumber;
+	double balance;
+	
+	/* Declaring methods - represent operations */
+
+	/*
+	 * Here is a useless destructor just for testing.
+	 */
+	public void finalize() {
+		System.out.println("Object is being descarded");
+		System.exit(0);
+	}
+	
+	public void withdraw(double amount) {
+		if (balance >= amount) {
+			balance = balance - amount;
+		}
+	}
+
+	public void deposit(double amount) {
+		balance += amount;
+	}
+	
+	public double getBalance() {
+		return balance;
+	}
+	
+}
diff --git a/oop/05-destructor/AccountTest.java b/oop/05-destructor/AccountTest.java
new file mode 100644
index 0000000..8c9f474
--- /dev/null
+++ b/oop/05-destructor/AccountTest.java
@@ -0,0 +1,19 @@
+
+public class AccountTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Account a1 = new Account();
+		//....
+		//....
+		a1 = new Account();
+		
+		while (true) {
+			new Account();
+		}
+		
+	}
+
+}
diff --git a/oop/06-encapsulation/.gitignore b/oop/06-encapsulation/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/06-encapsulation/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/06-encapsulation/Account.java b/oop/06-encapsulation/Account.java
new file mode 100644
index 0000000..55d99d0
--- /dev/null
+++ b/oop/06-encapsulation/Account.java
@@ -0,0 +1,29 @@
+
+public class Account {
+	
+	/* Declaring fields  - represent state */
+	
+	private int accountNumber;
+	private double balance;
+	
+	
+	/* Declaring methods - represent operations */
+	
+	public void withdraw(double amount) {
+		if (balance >= amount) {
+			balance = balance - amount;
+		}
+	}
+
+	public void deposit(double amount) {
+		balance += amount;
+	}
+	
+	public double getBalance() {
+		return balance;
+	}
+	
+	public void setBalance(double newBalance) {
+		balance = newBalance;
+	}
+}
diff --git a/oop/06-encapsulation/AccountTest.java b/oop/06-encapsulation/AccountTest.java
new file mode 100644
index 0000000..9242cea
--- /dev/null
+++ b/oop/06-encapsulation/AccountTest.java
@@ -0,0 +1,16 @@
+
+public class AccountTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Account a1 = new Account(); // Instantiation of 'Account' class
+		
+		a1.setBalance(200.0);
+		
+//		a1.deposit(100.0);
+//		a1.withdraw(10.0);
+	}
+
+}
diff --git a/oop/07-inheritance/.gitignore b/oop/07-inheritance/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/07-inheritance/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/07-inheritance/Account.java b/oop/07-inheritance/Account.java
new file mode 100644
index 0000000..91acb95
--- /dev/null
+++ b/oop/07-inheritance/Account.java
@@ -0,0 +1,24 @@
+
+public abstract class Account {
+	
+	/* Declaring fields  - represent state */
+	protected int accountNumber;
+	protected double balance;
+	
+	public Account() {
+		/// 
+	}
+	
+	/* Declaring methods - represent operations */
+	
+	public abstract void withdraw(double amount);
+	
+	public void deposit(double amount) {
+		balance += amount;
+	}
+	
+	public double getBalance() {
+		return balance;
+	}
+	
+}
diff --git a/oop/07-inheritance/AccountTest.java b/oop/07-inheritance/AccountTest.java
new file mode 100644
index 0000000..cc5056b
--- /dev/null
+++ b/oop/07-inheritance/AccountTest.java
@@ -0,0 +1,22 @@
+
+public class AccountTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		SavingsAccount a1 = new SavingsAccount();
+	
+		Account a3 = new SavingsAccount();
+				
+		Account a2 = new CheckingAccount();
+		
+
+		
+		CheckingAccount a4 = new CheckingAccount();
+		
+		
+//		CheckingAccount a5 = new SavingsAccount(); // not working
+	}
+
+}
diff --git a/oop/07-inheritance/CheckingAccount.java b/oop/07-inheritance/CheckingAccount.java
new file mode 100644
index 0000000..a7c19b8
--- /dev/null
+++ b/oop/07-inheritance/CheckingAccount.java
@@ -0,0 +1,20 @@
+
+public class CheckingAccount extends Account {
+	
+	
+	protected double overdraftLimit;
+
+
+	public void withdraw(double amount) {
+		double finalBalance = balance - amount;
+		if (finalBalance < 0) {
+			if (-finalBalance <= overdraftLimit) {
+				balance = finalBalance;
+			} else {
+				// throw exception
+			}
+		} else {
+			balance =  finalBalance;
+		}
+	}
+}
diff --git a/oop/07-inheritance/SavingsAccount.java b/oop/07-inheritance/SavingsAccount.java
new file mode 100644
index 0000000..497fb3d
--- /dev/null
+++ b/oop/07-inheritance/SavingsAccount.java
@@ -0,0 +1,9 @@
+
+public class SavingsAccount extends Account {
+
+	public void withdraw(double amount) {
+		if (balance >= amount) {
+			balance = balance - amount;
+		}
+	}
+}
diff --git a/oop/08-pass-by-value-reference/.gitignore b/oop/08-pass-by-value-reference/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/08-pass-by-value-reference/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/08-pass-by-value-reference/Customer.java b/oop/08-pass-by-value-reference/Customer.java
new file mode 100644
index 0000000..d092a3d
--- /dev/null
+++ b/oop/08-pass-by-value-reference/Customer.java
@@ -0,0 +1,12 @@
+public class Customer {
+	private int number;
+
+	public int getNumber() {
+		return number;
+	}
+
+	public void setNumber(int number) {
+		this.number = number;
+	}
+	
+}
diff --git a/oop/08-pass-by-value-reference/PassByReference.java b/oop/08-pass-by-value-reference/PassByReference.java
new file mode 100644
index 0000000..8eb577a
--- /dev/null
+++ b/oop/08-pass-by-value-reference/PassByReference.java
@@ -0,0 +1,19 @@
+public class PassByReference {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		Customer c = new Customer();
+		c.setNumber(5);
+		System.out.println(c.getNumber()); // 5
+		methodX(c);
+		System.out.println(c.getNumber()); // ?
+	}
+
+	public static void methodX(Customer c2) {
+		System.out.println(c2.getNumber()); // 5
+		c2.setNumber(6);
+		System.out.println(c2.getNumber()); // 6
+	}
+}
diff --git a/oop/08-pass-by-value-reference/PassByValue.java b/oop/08-pass-by-value-reference/PassByValue.java
new file mode 100644
index 0000000..2500d03
--- /dev/null
+++ b/oop/08-pass-by-value-reference/PassByValue.java
@@ -0,0 +1,17 @@
+public class PassByValue {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		int x = 4;
+		System.out.println(x); // 4
+		method(x, 2);
+		System.out.println(x); // ?
+	}
+
+	public static void method(int x, int b) {
+		x = x + 1;
+		System.out.println(x); // 5
+	}
+}
diff --git a/oop/09-polymorphism/.gitignore b/oop/09-polymorphism/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/09-polymorphism/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/09-polymorphism/Customer.java b/oop/09-polymorphism/Customer.java
new file mode 100644
index 0000000..56b0f7b
--- /dev/null
+++ b/oop/09-polymorphism/Customer.java
@@ -0,0 +1,60 @@
+public class Customer {
+	private int customerNumber;
+	private String name;
+	private String address;
+	private String phone;
+	private String mobile;
+
+	public Customer() {
+	}
+
+	public Customer(int customerNumber, String name, String address,
+			String phone, String mobile) {
+		this.customerNumber = customerNumber;
+		this.name = name;
+		this.address = address;
+		this.phone = phone;
+		this.mobile = mobile;
+	}
+
+	public int getCustomerNumber() {
+		return customerNumber;
+	}
+
+	public void setCustomerNumber(int customerNumber) {
+		this.customerNumber = customerNumber;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public String getAddress() {
+		return address;
+	}
+
+	public void setAddress(String address) {
+		this.address = address;
+	}
+
+	public String getPhone() {
+		return phone;
+	}
+
+	public void setPhone(String phone) {
+		this.phone = phone;
+	}
+
+	public String getMobile() {
+		return mobile;
+	}
+
+	public void setMobile(String mobile) {
+		this.mobile = mobile;
+	}
+
+}
diff --git a/oop/09-polymorphism/CustomerApp.java b/oop/09-polymorphism/CustomerApp.java
new file mode 100644
index 0000000..79e1c31
--- /dev/null
+++ b/oop/09-polymorphism/CustomerApp.java
@@ -0,0 +1,46 @@
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+public class CustomerApp {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		List list = new LinkedList();
+		
+		Customer c = new Customer(1, "Kamal", "Nugegoda", "123456", "654321");
+		list.add(c);
+
+		c = new Customer(2, "Nimal", "Colombo", "2234343", "2343433");
+		list.add(c);
+
+		c = new PremiumCustomer(1, "Sunil", "Kohuwala", "23443434", "9888234",
+				"a", "Give him whatever he ask");
+		list.add(c);
+		
+		list.add(new Date());
+		
+		Iterator itr = list.iterator();
+		
+		CustomerDetailsFormatter formatter = new CustomerDetailsFormatter();
+		
+		while (itr.hasNext()) {
+			Customer customer = (Customer) itr.next(); // Convert "java.lang.Object" to "Customer"
+			String formattedString = formatter.getFormattedDescription(customer);
+			System.out.println(formattedString);
+		}
+
+		/*
+		Account a1 = new SavingsAccount(); // Coercion (implicit conversion) 
+		a1.accountClassMethod();
+		
+		Account a1 = someMethod();
+		SavingsAccount sa = (SavingsAccount) a1; // Down casting
+		sa.savingsAccountClassMethod();
+		*/
+	}
+}
diff --git a/oop/09-polymorphism/CustomerDetailsFormatter.java b/oop/09-polymorphism/CustomerDetailsFormatter.java
new file mode 100644
index 0000000..d2640e0
--- /dev/null
+++ b/oop/09-polymorphism/CustomerDetailsFormatter.java
@@ -0,0 +1,17 @@
+public class CustomerDetailsFormatter {
+	
+	/**
+	 * Format the customer object according to some needs
+	 * @param c
+	 * @return
+	 */
+	public String getFormattedDescription(Customer c) {
+		String buffer = "Customer description: \n";
+		buffer += " Number: " + c.getCustomerNumber();
+		buffer += " Name: " + c.getName();
+		buffer += " Address: " + c.getAddress();
+		buffer += "\n";
+
+		return buffer;
+	}
+}
diff --git a/oop/09-polymorphism/PremiumCustomer.java b/oop/09-polymorphism/PremiumCustomer.java
new file mode 100644
index 0000000..a098af5
--- /dev/null
+++ b/oop/09-polymorphism/PremiumCustomer.java
@@ -0,0 +1,43 @@
+public class PremiumCustomer extends Customer {
+	
+	private String category;
+	private String desction;
+	
+	
+	public PremiumCustomer() {
+	}
+	
+	public PremiumCustomer(int customerNumber, String name, String address,
+			String phone, String mobile) {
+		super(customerNumber, name, address, phone, mobile);
+	}
+
+	
+	public PremiumCustomer(int customerNumber, String name, String address,
+			String phone, String mobile, String category, String desction) {
+		super(customerNumber, name, address, phone, mobile);
+		this.category = category;
+		this.desction = desction;
+	}
+
+	public PremiumCustomer(String category, String desction) {
+		super();
+		this.category = category;
+		this.desction = desction;
+	}
+
+	public String getCategory() {
+		return category;
+	}
+	public void setCategory(String category) {
+		this.category = category;
+	}
+	public String getDesction() {
+		return desction;
+	}
+	public void setDesction(String desction) {
+		this.desction = desction;
+	}
+
+	
+}
diff --git a/oop/10-nested-classes/.gitignore b/oop/10-nested-classes/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/oop/10-nested-classes/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/oop/10-nested-classes/CreateInner.java b/oop/10-nested-classes/CreateInner.java
new file mode 100644
index 0000000..ab3830e
--- /dev/null
+++ b/oop/10-nested-classes/CreateInner.java
@@ -0,0 +1,16 @@
+public class CreateInner {
+
+	public static void main(String[] args) {
+		MyOuter mo = new MyOuter();
+		MyOuter.MyInner inner = mo.new MyInner();
+		inner.seeOuter();
+	}
+
+	/* Here's another way (same thing!)
+	public static void main(String[] args) {
+		MyOuter.MyInner inner = new MyOuter().new MyInner();
+		inner.seeOuter();
+	}
+	*/
+
+}
diff --git a/oop/10-nested-classes/MyOuter.java b/oop/10-nested-classes/MyOuter.java
new file mode 100644
index 0000000..6821b98
--- /dev/null
+++ b/oop/10-nested-classes/MyOuter.java
@@ -0,0 +1,14 @@
+class MyOuter {
+   private int x = 7;
+   
+   public void makeInner() {
+      MyInner in = new MyInner();
+      in.seeOuter();
+   }
+   
+   class MyInner {
+      public void seeOuter() {
+         System.out.println("Outer x is " + x);
+      }
+   } 
+}
\ No newline at end of file