yclim95/javaDesignPatternsArchitecturePart1.md

## javaDesignPatternsArchitecturePart1.md

      
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              javaDesignPatternsArchitecturePart1.md
            
          
    #Java Design Patterns and Architecture Part I
##Lesson 1 : What is Model-View Controller(MVC) ?

Model ==> Data

....1.  Model will notify the **VIEW** (data changed) 
....2.  BackEND
....3.  Responds to requests for information about its state (usually from the **VIEW**)
....4.  Responds to instructions to change state (usually from the **CONTROLLER**).


View ==> GUI ==> A system that interacts with the user

....1. Make Request for DATA from the **MODEL** 
....2. Represent the data
....3. Manage the information displayed 


Controller ==> Business LoGic

....1. Informing the  **MODEL** & **VIEW** upon receiving response(detect) from User => to change accordingly 

##Lesson 2 : Simple MVC structure Using Swing (Example)
Notice at the package listing at the below code.... all of them are all in separate packages which is a good practice.... Model, View, Controller, and the Main class should be separated espcially Model and View.
Application.java
/*
 *  ///////   MAIN    //////////
*/
package com.yclim.designpatterns.demo1;

import javax.swing.SwingUtilities;

import com.yclim.designpatterns.demo1.controller.Controller;
import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.View;

public class Application {

	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {

			@Override
			public void run() {
				runApp();
			}
			
		});
	}//ENDof MAIN
	
	public static void runApp(){
		//Import Model class 
		Model model = new Model();
		//Import MODEL into View 
		View view = new View(model);
		//Controller -> Send commands/ listen to -> Model & View
		Controller controller = new Controller(model, view);
	}//ENDof RunApp()
}
Controller.java
/*
 *  ///////   CONTROLLER    //////////
*/
package com.yclim.designpatterns.demo1.controller;

import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.View;

public class Controller {
	private Model model;
	private View view;
	public Controller(Model model, View view) {
		this.model = model;
		this.view = view;
	}
	
}
Model.java
/*
 *  ///////   MODEL    //////////
*/
package com.yclim.designpatterns.demo1.model;

public class Model { //Does NOT import anything especially VIEW

}
View.java
/*
 *  ///////   VIEW    //////////
*/
package com.yclim.designpatterns.demo1.view;

import java.awt.HeadlessException;

import javax.swing.JFrame;

import com.yclim.designpatterns.demo1.model.Model;

public class View extends JFrame{
	private Model model;

	public View(Model model) throws HeadlessException {
		super("MVC Demo");
		this.model = model;
	}
	
}
##Lesson 3 : Observer Pattern (How Controller-View)
Observer Pattern is common used in GUI and Event-Driven application. Observer Pattern is a vital pattern for constructing user interfaces and often useful even in non-user-interface coding.
##Lesson 4 : Application on Observer Pattern (Using Button)
Application.java
/*
 *  ///////   MAIN    //////////
*/
package com.yclim.designpatterns.demo1;

import javax.swing.SwingUtilities;

import com.yclim.designpatterns.demo1.controller.Controller;
import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.View;

public class Application {

	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {

			@Override
			public void run() {
				runApp();
			}
			
		});
	}//ENDof MAIN
	
	public static void runApp(){
		//Import Model class 
		Model model = new Model();
		//Import MODEL into View 
		View view = new View(model);
		//Controller -> Send commands/ listen to -> Model & View
		Controller controller = new Controller(model, view);
	}//ENDof RunApp()
}
Controller.java
/*
 *  ///////   CONTROLLER    //////////
*/
package com.yclim.designpatterns.demo1.controller;

import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.View;

public class Controller {
	private Model model;
	private View view;
	public Controller(Model model, View view) {
		this.model = model;
		this.view = view;
	}
	
}
Model.java
/*
 *  ///////   MODEL    //////////
*/
package com.yclim.designpatterns.demo1.model;

public class Model { //Does NOT import anything especially VIEW

}
View.java
/*
 *  ///////   VIEW    //////////
*/
package com.yclim.designpatterns.demo1.view;

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

import com.yclim.designpatterns.demo1.model.Model;

public class View extends JFrame implements ActionListener{
	private Model model;
	private JButton helloButton;
	private JButton goodByeButton;

	public View(Model model) throws HeadlessException {
		super("MVC Demo");
		this.model = model;
		
		helloButton = new JButton("Hello");
		goodByeButton = new JButton("GoodBye");
		setLayout(new GridBagLayout());
		
		GridBagConstraints gc = new GridBagConstraints();
		gc.anchor = GridBagConstraints.CENTER; //Smaller < displayArea
		gc.gridx = 1;
		gc.gridy = 1;
		gc.weightx = 1;
		gc.weighty = 1; //Vertical Spaces
		gc.fill = GridBagConstraints.NONE;
		
		add(helloButton, gc); //Set Params ==> for Button to appear
		
		gc.anchor = GridBagConstraints.CENTER; //Smaller < displayArea
		gc.gridx = 1;
		gc.gridy = 2;
		gc.weightx = 1;
		gc.weighty = 1; //Vertical Spaces
		gc.fill = GridBagConstraints.NONE;
		
		
		add(goodByeButton, gc); //Set Params ==> for Button to appear
		
		
		/*
		 * add => List of ....
		 * set => only 1 thing 
		 */
		helloButton.addActionListener(this); // => run actionPerformed()
		goodByeButton.addActionListener(this);
		
		setSize(600,500); //(Width, Heigh)
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setVisible(true);
	}

	@Override
	public void actionPerformed(ActionEvent e) {
		JButton source = (JButton) e.getSource(); //Get the reference on which button has inovke this
 		if (source == helloButton){
 			System.out.println("Hello there");
 		}else{
 			System.out.println("Some other BUTTON");
 		}
 		
	}//ENDof ActionPerformed()
	
}
##Lesson 5 : Observer Pattern : Implementing From Strach (with MVC)
Application.java
/*
 *  ///////   MAIN    //////////
*/
package com.yclim.designpatterns.demo1;

import javax.swing.SwingUtilities;

import com.yclim.designpatterns.demo1.controller.Controller;
import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.View;

public class Application {

	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {

			@Override
			public void run() {
				runApp();
			}
			
		});
	}//ENDof MAIN
	
	public static void runApp(){
		//Import Model class 
		Model model = new Model();
		//Import MODEL into View 
		View view = new View(model);
		//Controller -> Send commands/ listen to -> Model & View
		Controller controller = new Controller(model, view);
		
		//Passing a reference of CONTROLLER to the VIEW
		//View does not know that the thing that is passed is a CONTROLLER 
		// All it know is that that thing  has a method loginPerformed()
		view.setLoginListener(controller); 
	}//ENDof RunApp()
}
Controller.java
/*
 *  ///////   CONTROLLER    //////////
*/
package com.yclim.designpatterns.demo1.controller;

import com.yclim.designpatterns.demo1.model.Model;
import com.yclim.designpatterns.demo1.view.LoginFormEvent;
import com.yclim.designpatterns.demo1.view.LoginListener;
import com.yclim.designpatterns.demo1.view.View;

public class Controller implements LoginListener{
	private Model model;
	private View view;
	public Controller(Model model, View view) {
		this.model = model;
		this.view = view;
	}
	@Override
	public void loginPerformed(LoginFormEvent event) {
		System.out.println("Login Event Recieved. " + event.getName() + " ; " + event.getPassword());
	}
	
}
Model.java
/*
 *  ///////   MODEL    //////////
*/
package com.yclim.designpatterns.demo1.model;

public class Model { //Does NOT import anything especially VIEW

}
View.java
/*
 *  ///////   VIEW    //////////
 */
package com.yclim.designpatterns.demo1.view;

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.HeadlessException;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

import com.yclim.designpatterns.demo1.model.Model;

public class View extends JFrame implements ActionListener {
	private Model model;
	private JButton okButton;
	private JTextField nameField;
	private JPasswordField passField;

	private LoginListener loginListener;

	public View(Model model) throws HeadlessException {
		super("MVC Demo");
		this.model = model;

		// Create
		nameField = new JTextField(10);
		passField = new JPasswordField(10);
		okButton = new JButton("OK");

		// Set Layout
		setLayout(new GridBagLayout());

		// Give the layout style to the view
		GridBagConstraints gc = new GridBagConstraints();
		gc.anchor = GridBagConstraints.LAST_LINE_END;
		gc.gridx = 1;
		gc.gridy = 1;
		gc.weightx = 1;
		gc.weighty = 1;
		gc.insets = new Insets(100, 0, 0, 10);
		gc.fill = GridBagConstraints.NONE;

		add(new JLabel("Name: "), gc);

		gc.anchor = GridBagConstraints.LAST_LINE_START;
		gc.gridx = 2;
		gc.gridy = 1;
		gc.weightx = 1;
		gc.weighty = 1;
		gc.insets = new Insets(100, 0, 0, 0);
		gc.fill = GridBagConstraints.NONE;

		add(nameField, gc);

		gc.anchor = GridBagConstraints.LINE_END;
		gc.gridx = 1;
		gc.gridy = 2;
		gc.weightx = 1;
		gc.weighty = 1;
		gc.insets = new Insets(0, 0, 0, 10);
		gc.fill = GridBagConstraints.NONE;

		add(new JLabel("Password: "), gc);

		gc.anchor = GridBagConstraints.LINE_START;
		gc.gridx = 2;
		gc.gridy = 2;
		gc.weightx = 1;
		gc.weighty = 1;
		gc.insets = new Insets(0, 0, 0, 0);
		gc.fill = GridBagConstraints.NONE;

		add(passField, gc);

		gc.anchor = GridBagConstraints.FIRST_LINE_START;
		gc.gridx = 2;
		gc.gridy = 3;
		gc.weightx = 1;
		gc.weighty = 100;
		gc.fill = GridBagConstraints.NONE;

		add(okButton, gc);

		okButton.addActionListener(this);

		setSize(600, 500);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setVisible(true);

	}

	@Override
	public void actionPerformed(ActionEvent e) {
		String password = new String(passField.getPassword());
		String name = nameField.getText();
		
		fireLoginEvent(new LoginFormEvent(name, password) );

	}// ENDof ActionPerformed()

	public void setLoginListener(LoginListener loginListener) {
		this.loginListener = loginListener;
	}

	public void fireLoginEvent(LoginFormEvent event) {
		// Check if loginListener is called
		if (loginListener != null) {
			loginListener.loginPerformed(event);
		}
	}

}
LoginListener.java(Interface)
package com.yclim.designpatterns.demo1.view;

public interface LoginListener {
	public void loginPerformed(LoginFormEvent event);
}
LoginFormEvent.java
package com.yclim.designpatterns.demo1.view;

public class LoginFormEvent { //Hold Data of a form 
	private String name;
	private String password;
	
	public LoginFormEvent(String name, String password) {
		this.name = name;
		this.password = password;
	}

	public String getName() {
		return name;
	}

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

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
	
}
OUTPUT (At Console)
Login Event Recieved. YC ; 123

For FULL Codes Click Here
##Resources

Click HERE to Java Design Patterns and Architecture Part II
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