MVC Paradigm The MVC paradigm breaks applications or interfaces into three parts: the model, the view, and the controller. A --> 25 % B --> 60 % C --> 15 % Model Users interact with a controller (e.g., buttons), and make changes to the model (e.g., data), which is then reflected in the view (e.g., graph). Control View(s) Draw Graph

MVC Relationships The Controller has references to both the view and the model; the controller is the base of the triad. The Model might have a reference to the view, to allow for notification of changes. The model does not know who controls it, however. The View has a reference to the model, for gathering data. View also has reference to the Controller, to notify of successful updates. (References are minimal, perhaps to a base class, to allow swapping of controls.) Model View Controller MVC Relationships

import java. awt. ; import java. awt. event. ; import javax. swing import java.awt.*; import java.awt.event.*; import javax.swing.*; public class CounterDisplay extends JFrame implements ActionListener{ JButton incButton, decButton; JTextField counterField; //constructor public CounterDisplay(){ setLayout(new FlowLayout()); incButton = new JButton("INC"); decButton = new JButton("DEC"); counterField = new JTextField("1", 5); //add button and textfield to the frame add(incButton); add(decButton); add(counterField); //register the listener incButton.addActionListener(this); counterField.addActionListener(this); setSize(150,100); setVisible(true); } public void actionPerformed(ActionEvent e){ //if the event is generated by the incButton if (e.getSource() == incButton){ counterField.setText((new Integer(Integer.parseInt(counterField.getText())+1)).toString()); //decButton public static void main(String[] args){ CounterDisplay app = new CounterDisplay(); //create the display instance app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

public class Counter{ private int value; //constructor public Counter(int v){ value = v;} //set a value public void setValue(int v) {value = v;} //get current value public int getValue() {return value;} //increment the counter public void inc() {value++;} //decrement the counter public void dec() {value --;} }

/. Example of Model-Control-View. class CounterDisplay /** Example of Model-Control-View * class CounterDisplay * Control and display a Counter object */ public class CounterDisplay2 extends JFrame implements ActionListener{ Counter counter; //the Counter object to be controlled and displayed JButton incButton, decButton; JTextField counterField; //constructor public CounterDisplay2 (Counter aCounter){ counter = aCounter; setLayout(new FlowLayout()); incButton = new JButton("INC"); decButton = new JButton("DEC"); counterField = new JTextField("1", 5); //add button and textfield to the frame add(incButton); add(decButton); add(counterField); //register the listener incButton.addActionListener(this); counterField.addActionListener(this); setSize(150,100); setVisible(true); } public void actionPerformed(ActionEvent e){ //if the event is generated by the incButton if (e.getSource() == incButton){ counter.inc(); System.out.println(counter.getValue()); counterField.setText((new Integer(counter.getValue())).toString()); //if the event is generated by the decButton if (e.getSource() == decButton){ counter.dec(); //if ENTER is press on the text field if(e.getSource() == counterField){ counter.setValue(Integer.parseInt(counterField.getText()));

Another Example ShapeEditor