Java Design Pattern

[Adapter pattern]

public interface Print
{
 public abstract void printWeak();
 public abstract void printString();
 
}

public class Banner
{

 private String string;

 public Banner(String string)
 {

  this.string = string;
 }

 public void showWithParen()
 {

  System.out.println("(" + string + ")");
 }
 
 public void showWithAster()
 {
  System.out.println("*" + string +"*");
 }
}

public class PrintBanner extends Banner implements Print
{

 public PrintBanner(String string)
 {

  super(string);
  // TODO Auto-generated constructor stub
 }

 @Override
 public void printWeak()
 {

  // TODO Auto-generated method stub
  showWithParen();
  
 }

 @Override
 public void printString()
 {

  // TODO Auto-generated method stub
  showWithAster();
  
 }

}

public class Main
{

 /**
  * @param args
  */
 public static void main(String[] args)
 {

  // TODO Auto-generated method stub
  Print p = new PrintBanner("Hello");
  p.printWeak();
  p.printString();

 }

}

[Iterator pattern]

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

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

public class BookShelf implements Aggregate
{
 private Book[] books;
 private int last = 0;
 
 public BookShelf(int maxsize)
 {
  this.books = new Book[maxsize];
 }
 
 public Book getBookAt(int index)
 {
  return books[index];
 }
 
 public void appendBook(Book book)
 {
  this.books[last] = book;
  last++;
 }
 
 public int getLength()
 {
  return last;
 }

 @Override
 public Iterator iterator()
 {

  // TODO Auto-generated method stub
  return new BookShelfIterator(this);
 }

}

public class BookShelfIterator implements Iterator
{
 private BookShelf bookShelf;
 private int index;
 
 public BookShelfIterator(BookShelf bookShelf)
 {
  this.bookShelf = bookShelf;
  this.index = 0;
 }
 @Override
 public boolean hasNext()
 {

  // TODO Auto-generated method stub
  if(index < bookShelf.getLength())
   return true;
  else
   return false;
 }

 @Override
 public Object next()
 {

  // TODO Auto-generated method stub
  Book book = bookShelf.getBookAt(index);
  index++;
  return book;
 }

}
public class Book
{
 
 private String name = "";

 public Book(String name)
 {
  this.name = name;
 }
 public String getName()
 {
 
  return name;
 }

 
 public void setName(String name)
 {
 
  this.name = name;
 }
 
 
}

public class Main
{

 /**
  * @param args
  */
 public static void main(String[] args)
 {

  BookShelf bookShelf = new BookShelf(4);
  bookShelf.appendBook(new Book("Bible"));
  bookShelf.appendBook(new Book("Cinderella"));
  bookShelf.appendBook(new Book("Daddy"));
  
  Iterator it = bookShelf.iterator();
  while(it.hasNext())
  {
   Book book = (Book) it.next();
   System.out.println(""+book.getName());
  }

 }

}

[Template pattern]
public abstract class AbstractDisplay
{
 public abstract void open();
 public abstract void print();
 public abstract void close();
 
 public final void display()
 {
  open();
  
  for(int i=0; i<5; i++)
  {
   print();
  }
  
  close();
 }
}
public class CharDisplay extends AbstractDisplay
{
 private char ch;
 
 public CharDisplay(char ch)
 {
  this.ch = ch;
 }
 @Override
 public void open()
 {

  // TODO Auto-generated method stub
  System.out.print("<<");
  
 }

 @Override
 public void print()
 {

  // TODO Auto-generated method stub
  System.out.print(ch);
 }

 @Override
 public void close()
 {

  // TODO Auto-generated method stub
  System.out.println(">>");
 }

}
public class StringDisplay extends AbstractDisplay
{
 private String string;
 private int width;
 
 public StringDisplay(String string)
 {
  this.string = string;
  this.width = string.getBytes().length;
 }

 @Override
 public void open()
 {

  // TODO Auto-generated method stub
  printLine();
 }

 
 @Override
 public void print()
 {

  // TODO Auto-generated method stub
  System.out.println("|"+string+"|");
 }

 @Override
 public void close()
 {

  // TODO Auto-generated method stub
  printLine();
 }
 
 private void printLine()
 {

  // TODO Auto-generated method stub
  System.out.print("+");
  
        }

public class Main
{

 /**
  * @param args
  */
 public static void main(String[] args)
 {

  // TODO Auto-generated method stub
  AbstractDisplay d1 = new CharDisplay('H');
  
  AbstractDisplay d2 = new StringDisplay("Hello, world.");
  
  AbstractDisplay d3 = new StringDisplay("nice to you.");
  
  d1.display();
  d2.display();
  d3.display();
 }

}

[Factory Method Pattern]


Factory class

public abstract class Factory
{
 public final Product create(String owner)
 {
  Product p = createProduct(owner);
  registerProduct(p);
  return p;
 }
 
 protected abstract Product createProduct(String owner);
 protected abstract void  registerProduct(Product product);
}

Product class

public abstract class Product
{
 public abstract void use();
}
IDCardFactory class

public class IDCardFactory extends Factory
{
 private Vector owners = new Vector();
 @Override
 protected Product createProduct(String owner)
 {

  // TODO Auto-generated method stub
  return new IDCard(owner);
 }

 @Override
 protected void registerProduct(Product product)
 {

  // TODO Auto-generated method stub
  owners.add(((IDCard)product).getOwner());
 }

}
IDCard class

public class IDCard extends Product
{
 private String owner;
 IDCard(String owner)
 {
  System.out.println("create"+owner+"card");
  this.owner = owner;
 }
 @Override
 public void use()
 {

  System.out.println("use"+owner+"card");
  
 }
 
 public String getOwner()
 {
  return owner;
 }

}
Main class

public class Main
{

 /**
  * @param args
  */
 public static void main(String[] args)
 {

  // TODO Auto-generated method stub
  Factory factory = new IDCardFactory();
  Product card1 = factory.createProduct("test");
  Product card2 = factory.createProduct("test1");
  Product card3 = factory.createProduct("test2");
  card1.use();
  card2.use();
  card3.use();
  
 }

}