CSE564 Lecture 10

jgs CSE 564 Software Design Lecture 10: Design Patterns -
Decorator Dr. Javier Gonzalez-Sanchez javiergs@asu.edu javiergs.engineering.asu.edu | javiergs.com PERALTA 230U Office Hours: By appointment

jgs Decorator

Javier Gonzalez-Sanchez | CSE564 | Fall 2020 | 3 jgs
GoF Patterns

Decorator

Component abstract class Component { public abstract void operation(); }

ConcreteComponent class ConcreteComponent extends Component { @override public void operation() { System.out.print("ConcreteComponent-Operation()"); } }

Decorator abstract class Decorator extends Component { protected Component component; public void setComponent(Component component) { this.component = component; } @override public void operation() { if (component != null) { component.operation(); } } }

ConcreteDecoratorA class ConcreteDecoratorA extends Decorator { @override public void operation() { super.operation(); System.out.println("ConcreteDecoratorA-Operation()”); } }

ConcreteDecoratorB class ConcreteDecoratorB extends Decorator { @override public void operation() { super.operation(); addedBehavior(); System.out.println("ConcreteDecoratorB-Operation()"); } void addedBehavior() { } }

Main class MainApp { static void main() { // Create ConcreteComponent and two Decorators ConcreteComponent c = new ConcreteComponent(); ConcreteDecoratorA d1 = new ConcreteDecoratorA(); ConcreteDecoratorB d2 = new ConcreteDecoratorB(); // Link decorators d1.SetComponent(c); d2.SetComponent(d1); d2.Operation(); } }

Main class MainApp { static void main() { // Create ConcreteComponent and two Decorators ConcreteComponent c = new ConcreteComponent(); ConcreteDecoratorA d1 = new ConcreteDecoratorA(); ConcreteDecoratorB d2 = new ConcreteDecoratorB(); // Link decorators d1.SetComponent(c); d2.SetComponent(d1); d2.Operation(); } } ConcreteComponent - Operation() ConcreteDecoratorA - Operation() ConcreteDecoratorB - Operation()

Decorator vs Inheritance § Both allow you to change how an object behaves § The decorator pattern can be used to make it possible to extend (decorate) the functionality of a certain object at runtime. § Inheritance adds behavior at compilation-time.

Scenario CompanionHelper CompanionTroll Companion

Scenario CompanionHelper CompanionTroll Companion CompanionTrollHelper

jgs Case 1: Everything you need to know

Decorator

Main

Companion public interface Companion { public void doSomething(); }

BasicCompanion public class BasicCompanion implements Companion { @Override public void doSomething() { System.out.print("Hello Student, "); } }

CompanionDecorator public class CompanionDecorator implements Companion { protected Companion c; public void add(Companion c){ this.c = c; } @Override public void doSomething() { this.c.doSomething(); } }

HelperCompanion public class HelperCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to help you. "); } }

AffectiveCompanion public class AffectiveCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to cheer you."); } }

Main

jgs Case 2: Everything you need to know

GUI

Decorator

Main import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.*; public class Main extends JFrame implements ActionListener { CompanionPanel companionPanel = new CompanionPanel (); JButton b1 = new JButton("standard"); JButton b2 = new JButton("help"); JButton b3 = new JButton("affect"); JButton b4 = new JButton("helper+affect"); public Main() { setLayout(new BorderLayout(3,2)); add (companionPanel, BorderLayout.CENTER); JPanel control = new JPanel(new GridLayout(1,4)); control.add (b1); b1.addActionListener(this); control.add (b2); b2.addActionListener(this); control.add (b3); b3.addActionListener(this); control.add (b4); b4.addActionListener(this); add (control, BorderLayout.SOUTH); }

jgs @Override public void actionPerformed(ActionEvent e) { if (e.getSource()==b1) {
BasicCompanion basic = new BasicCompanion(); panel.setCompanion(basic); panel.showYourself(); } else if (e.getSource()==b2) { BasicCompanion basic = new BasicCompanion(); HelperCompanion helper = new HelperCompanion(); helper.add(basic); panel.setCompanion(helper); panel.showYourself(); } else if (e.getSource()==b3) { BasicCompanion basic = new BasicCompanion(); AffectiveCompanion h = new AffectiveCompanion(); h.add(basic); panel.setCompanion(h); panel.showYourself(); } else if (e.getSource()==b4) { HelperCompanion helper2 = new HelperCompanion(); AffectiveCompanion affective = new AffectiveCompanion(); BasicCompanion basic2 = new BasicCompanion(); helper2.add(affective); affective.add(basic2); panel.setCompanion(helper2);panel.showYourself(); } } public static void main(String[] args) { JFrame main = new Main(); main.setSize(500,500); main.setVisible(true); main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

CompanionPanel import java.awt.GridLayout; import javax.swing.JLayeredPane; public class CompanionPanel extends JLayeredPane{ public Companion brain; public void setCompanion(Companion x) { brain = x; } public void showYourself() { removeAll(); setLayout(new GridLayout(1,1)); brain.doSomething(this); revalidate(); } }

Companion import javax.swing.JComponent; public interface Companion { public void doSomething(JComponent panel); }

BasicCompanion import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JLabel; public class BasicCompanion implements Companion { @Override public void doSomething(JComponent panel) { ImageIcon face = new ImageIcon("src/face.png"); JLabel label = new JLabel(); label.setIcon(face); label.setHorizontalTextPosition(JLabel.CENTER); label.setVerticalTextPosition(JLabel.BOTTOM); label.setText("Hello Student, "); panel.add(label); } }

CompanionDecorator import javax.swing.JComponent; public class CompanionDecorator implements Companion { protected Companion c; public void add(Companion c){ this.c=c; } @Override public void doSomething(JComponent panel) { this.c.doSomething(panel); } }

AffectiveCompanion import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JLabel; public class AffectiveCompanion extends CompanionDecorator { @Override public void doSomething(JComponent panel){ super.doSomething(panel); ImageIcon face = new ImageIcon("src/cheer.png"); JLabel label = new JLabel(); label.setIcon(face); label.setHorizontalTextPosition(JLabel.CENTER); label.setVerticalTextPosition(JLabel.BOTTOM); label.setText("I am here to cheer you."); panel.add(label); } }

HelperCompanion import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JLabel; public class HelperCompanion extends CompanionDecorator { @Override public void doSomething(JComponent panel){ super.doSomething(panel); ImageIcon face = new ImageIcon("src/bubble.png"); JLabel label = new JLabel(); label.setIcon(face); label.setHorizontalTextPosition(JLabel.CENTER); label.setVerticalTextPosition(JLabel.BOTTOM); label.setText("I am here to help you."); panel.add(label); } }

GUI

jgs CSE 564 Computer Systems Fundamentals Javier Gonzalez-Sanchez javiergs@asu.edu Fall
2020 Disclaimer. These slides can only be used as study material for the class CSE564 at ASU. They cannot be distributed or used for another purpose.

CSE564 Lecture 10

CSE564 Lecture 10

More Decks by Javier Gonzalez

Other Decks in Programming

Featured

Transcript