Sample of Java Pattern -- Proxy

Order.java

package proxy;

import java.io.Serializable;
import java.util.Date;

public class Order implements Serializable {

    private int orderId;
    private String sku;
    private Date createdOn;
    private Date updatedOn;
    private int status;
    
    public int getOrderId() {
        return orderId;
    }
    public void setOrderId(int orderId) {
        this.orderId = orderId;
    }
    public String getSku() {
        return sku;
    }
    public void setSku(String sku) {
        this.sku = sku;
    }
    public Date getCreatedOn() {
        return createdOn;
    }
    public void setCreatedOn(Date createdOn) {
        this.createdOn = createdOn;
    }
    public Date getUpdatedOn() {
        return updatedOn;
    }
    public void setUpdatedOn(Date updatedOn) {
        this.updatedOn = updatedOn;
    }
    public int getStatus() {
        return status;
    }
    public void setStatus(int status) {
        this.status = status;
    }
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((sku == null) ? 0 : sku.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;
        Order other = (Order) obj;
        if (sku == null) {
            if (other.sku != null)
                return false;
        } else if (!sku.equals(other.sku))
            return false;
        return true;
    }
}

OrderDAO.java

package proxy;

import java.util.List;

public interface OrderDAO {
    public List<Order> getAllOrders();
}

OrderDAOImpl.java

package proxy;

import java.util.ArrayList;
import java.util.List;

public class OrderDAOImpl implements OrderDAO{
    public List<Order> getAllOrders(){
        List<Order> list = new ArrayList<Order>();
        for(int i =0; i<10; i++){
            Order order = new Order();
            order.setSku("sku"+i);
            list.add(order);
        }
        return list;
    }
}

OrderDAOProxy.java

package proxy;

import java.util.List;

public class OrderDAOProxy implements OrderDAO{
    public List<Order> getAllOrders(){
        long stTime = System.currentTimeMillis();
        OrderDAO orderDAOImpl = new OrderDAOImpl();
        List<Order> list = orderDAOImpl.getAllOrders();
        long endTime = System.currentTimeMillis();
        System.out.println("took " + (endTime - stTime) + " milliseconds.");
        return list;
    }
}

ProxyTest.java

package proxy;

public class ProxyTest {

    public static void main(String[] args) {
        OrderDAO orderDAOProxy = new OrderDAOProxy();
        orderDAOProxy.getAllOrders();
    }

}

you may download the source code.

Sample of Java Pattern -- State

OrderState.java

package state;

public interface OrderState {
    public void handleOrder(String orderNo);
    public void cancelOrder(String orderNo);
    public void completeOrder(String orderNo);
}

OrderOpendState.java

package state;

public class OrderOpendState implements OrderState {
    
    OrderStateMgmt orderStateMgmt;
    
    public OrderOpendState(OrderStateMgmt orderStateMgmt){
        this.orderStateMgmt = orderStateMgmt;
    }
    
    public void handleOrder(String orderNo){
        System.out.println("handle this order, orderNo=" + orderNo);
        orderStateMgmt.setState(orderStateMgmt.getOrderInProgressState());
    }
    
    public void cancelOrder(String orderNo){
        System.out.println("cancel this order, orderNo=" + orderNo);
        orderStateMgmt.setState(orderStateMgmt.getOrderCancelledState());
    }
    
    public void completeOrder(String orderNo){
        System.out.println("could not complete this order under opend status, orderNo=" + orderNo);
    }
}

OrderInProgressState.java

package state;

public class OrderInProgressState implements OrderState {
    
    OrderStateMgmt orderStateMgmt;
    
    public OrderInProgressState(OrderStateMgmt orderStateMgmt){
        this.orderStateMgmt = orderStateMgmt;
    }
    
    public void handleOrder(String orderNo){
        System.out.println("could not handle this order under in progress status, orderNo=" + orderNo);
    }
    
    public void cancelOrder(String orderNo){
        System.out.println("cancel this order, orderNo=" + orderNo);
        orderStateMgmt.setState(orderStateMgmt.getOrderCancelledState());
    }
    
    public void completeOrder(String orderNo){
        System.out.println("complete this order, orderNo=" + orderNo);
        orderStateMgmt.setState(orderStateMgmt.getOrderClosedState());
    }
}

OrderCancelledState.java

package state;

public class OrderCancelledState implements OrderState {
    
    OrderStateMgmt orderStateMgmt;
    
    public OrderCancelledState(OrderStateMgmt orderStateMgmt){
        this.orderStateMgmt = orderStateMgmt;
    }
    
    public void handleOrder(String orderNo){
        System.out.println("could not handle this order under cancelled status, orderNo=" + orderNo);
    }
    
    public void cancelOrder(String orderNo){
        System.out.println("could not cancel this order under cancelled status, orderNo=" + orderNo);
    }
    
    public void completeOrder(String orderNo){
        System.out.println("could not complete this order under cancelled status, orderNo=" + orderNo);
    }
}

OrderClosedState.java

package state;

public class OrderClosedState implements OrderState {
    
    OrderStateMgmt orderStateMgmt;
    
    public OrderClosedState(OrderStateMgmt orderStateMgmt){
        this.orderStateMgmt = orderStateMgmt;
    }
    
    public void handleOrder(String orderNo){
        System.out.println("could not handle this order under closed status, orderNo=" + orderNo);
    }
    
    public void cancelOrder(String orderNo){
        System.out.println("could not cancel this order under closed status, orderNo=" + orderNo);
    }
    
    public void completeOrder(String orderNo){
        System.out.println("could not complete this order under closed status, orderNo=" + orderNo);
    }
}

OrderStateMgmt.java

package state;

public class OrderStateMgmt {
    
    private OrderOpendState orderOpendState;
    private OrderInProgressState orderInProgressState;
    private OrderCancelledState orderCancelledState;
    private OrderClosedState orderClosedState;
    
    private OrderState orderState;
    
    public OrderStateMgmt(){
        this.orderOpendState = new OrderOpendState(this);
        this.orderInProgressState = new OrderInProgressState(this);
        this.orderCancelledState = new OrderCancelledState(this);
        this.orderClosedState = new OrderClosedState(this);
        this.orderState = this.orderOpendState;
        System.out.println("The order inital status is: opend.");
    }
    
    public void setState(OrderState orderState){
        this.orderState = orderState;
    }

    public OrderOpendState getOrderOpendState() {
        return orderOpendState;
    }

    public OrderInProgressState getOrderInProgressState() {
        return orderInProgressState;
    }

    public OrderCancelledState getOrderCancelledState() {
        return orderCancelledState;
    }

    public OrderClosedState getOrderClosedState() {
        return orderClosedState;
    }

    public void handleOrder(String orderNo){
        orderState.handleOrder(orderNo);
    }
    
    public void cancelOrder(String orderNo){
        orderState.cancelOrder(orderNo);
    }
    
    public void completeOrder(String orderNo){
        orderState.completeOrder(orderNo);
    }
}

OrderStateTest.java

package state;

public class OrderStateTest {

    public static void main(String[] args) {
        OrderStateMgmt orderStateMgmtA = new OrderStateMgmt();
        
        orderStateMgmtA.handleOrder("01");
        orderStateMgmtA.completeOrder("01");

        OrderStateMgmt orderStateMgmtB = new OrderStateMgmt();

        orderStateMgmtB.handleOrder("02");
        orderStateMgmtB.cancelOrder("02");
        
        OrderStateMgmt orderStateMgmtC = new OrderStateMgmt();

        orderStateMgmtC.completeOrder("03");
    }

}

you may download the source code.

Sample of Java Pattern -- Composite

Department.java

package composite;

import java.util.List;

public interface Department {
    public Department getDepartment();
    public String getDepartmentname();
    public void add(Department department);
    public void remove(Department department);
    public boolean hasSubDepartments();
    public List<Department> getSubDepartments();
}

CompositeDepartment.java

package composite;

import java.util.ArrayList;
import java.util.List;

public class CompositeDepartment implements Department {
    private String name;
    private List<Department> departments = new ArrayList<Department>();
    
    public CompositeDepartment(String name) {
        super();
        System.out.println("Department " + name + " is created.");
        this.name = name;
    }

    public Department getDepartment() {
        return this;
    }

    public String getDepartmentname() {
        return this.name;
    }
    
    public void add(Department department){
        System.out.println("Department " + department.getDepartmentname() + " is added to Department " + this.name + ".");
        departments.add(department);
    }

    public void remove(Department department){
        System.out.println("Department " + department.getDepartmentname() + " is removed from Department " + this.name + ".");
        departments.remove(department);
    }

    public boolean hasSubDepartments(){
        if(departments == null || departments.isEmpty())
            return false;
        return true;
    }
    
    public List<Department> getSubDepartments(){
        if(hasSubDepartments())
            return departments;
        return null;
    }
}

SingleDepartment.java

package composite;

import java.util.List;

public class SingleDepartment implements Department {
    private String name;
    
    public SingleDepartment(String name) {
        super();
        System.out.println("Department " + name + " is created.");
        this.name = name;
    }

    public Department getDepartment() {
        return this;
    }

    public String getDepartmentname() {
        return this.name;
    }

    public void add(Department department){
        System.out.println("Could not add a child department in Department " + this.name + ".");
    }

    public void remove(Department department){
        System.out.println("Department " + department.getDepartmentname() + " doesn't belong to Department " + this.name + ".");
    }
    
    public boolean hasSubDepartments(){
        return false;
    }
    
    public List<Department> getSubDepartments(){
        return null;
    }
}

CompositeTest.java

package composite;

public class CompositeTest {
    public static void main(String[] args) {
        Department hq = new CompositeDepartment("HQ");
        Department financing = new SingleDepartment("Financing");
        Department marketing = new CompositeDepartment("Marketing");
        Department preSales = new SingleDepartment("PreSales");
        Department sales = new SingleDepartment("Sales");
        Department postSales = new SingleDepartment("PostSales");
        Department techSupport = new SingleDepartment("TechSupport");
        hq.add(financing);
        hq.add(marketing);
        hq.add(techSupport);
        marketing.add(preSales);
        marketing.add(sales);
        marketing.add(postSales);
        System.out.println("hq has sub departments: " + hq.hasSubDepartments());
        System.out.println("marketing has sub departments: " + marketing.hasSubDepartments());
        System.out.println("techSupport has sub departments: " + techSupport.hasSubDepartments());
        marketing.remove(preSales);
        marketing.remove(sales);
        marketing.remove(postSales);
        sales.remove(preSales);
        hq.remove(financing);
        hq.remove(marketing);
        hq.remove(techSupport);
    }
}

you may download the source code.

Sample of Java Pattern -- Iterator

Aggregate.java

package iterator;

public interface Aggregate {
    public abstract Iterator iterator();
}

Iterator.java

package iterator;

public interface Iterator {
    public abstract boolean hasNext();  
    public abstract Object next();  
}

Order.java

package iterator;

import java.util.Date;

public class Order {
    private String name;
    private Date createdOn = new Date();
    private Date updatedOn = new Date();
    
    public Order(String name) {
        super();
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Date getCreatedOn() {
        return createdOn;
    }
    public void setCreatedOn(Date createdOn) {
        this.createdOn = createdOn;
    }
    public Date getUpdatedOn() {
        return updatedOn;
    }
    public void setUpdatedOn(Date updatedOn) {
        this.updatedOn = updatedOn;
    }
}

Orders.java

package iterator;

import java.util.Date;

public class Orders implements Aggregate{
    private Order[] orders;
    private int last = 0;
    
    public Orders(int max){
        this.orders = new Order[max];
    }
    
    public Order getOrderAt(int index){
        return this.orders[index];
    }
    
    public void appendOrder(Order order){
        this.orders[last] = order;
        this.last ++ ;
    }
    
    public int getLength(){
        return orders.length;
    }
    
    public Iterator iterator() {
        return new OrdersIterator(this);
    }
}

OrdersIterator.java

package iterator;

public class OrdersIterator implements Iterator{
    private Orders orders;
    private int index;
    
    public OrdersIterator(Orders orders) {
        this.orders = orders;
        this.index = 0;
    }
    
    public boolean hasNext(){
        if(index < orders.getLength()){
            return true;
        }else{
            return false;
        }
    }
    
    public Order next(){
        Order order = orders.getOrderAt(this.index);
        this.index ++ ;
        return order;
    }
}

IteratorTest.java

package iterator;

public class IteratorTest {

    public static void main(String[] args) {
        Orders orders = new Orders(3);
        orders.appendOrder(new Order("order1"));
        orders.appendOrder(new Order("order2"));
        orders.appendOrder(new Order("order3"));
        Iterator iterator = orders.iterator();
        while(iterator.hasNext()) {
            Order order = (Order)iterator.next();
            System.out.println(order.getName());
        }
    }

}

you may download the source code.