L19cs211sp07-6up

L19cs211sp07-6up - GUI Dynamics Lecture 19 CS211 – Spring...

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Unformatted text preview: GUI Dynamics Lecture 19 CS211 – Spring 2007 2 GUI Statics and GUI Dynamics y Statics: what’s drawn on the screen ¡ Components ¢ buttons, labels, lists, sliders, menus, ... ¡ Containers: components that contain other components ¢ frames, panels, dialog boxes, ... ¡ Layout managers: control placement and sizing of components y Dynamics: user interactions ¡ Events ¢ button-press, mouse-click, key- press, ... ¡ Listeners: an object that responds to an event ¡ Helper classes ¢ Graphics , Color , Font , FontMetrics , Dimension , ... 3 Dynamics Overview y Dynamics = causing and responding to actions ¡ What actions? ¢ Called events ¢ Need to write code that “understands” what to do when an event occurs ¡ In Java, you specify what happens by providing an object that “hears” the event ¢ In other languages, you specify what happens in response to an event by providing a function y What objects do we need? ¡ Events ¡ Event listeners 4 import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Intro extends JFrame { private int count = 0; private JButton myButton = new JButton( "Push Me!" ); private JLabel label = new JLabel( "Count: " + count ); public Intro() { setDefaultCloseOperation(JFrame. EXIT_ON_CLOSE ); setLayout( new FlowLayout(FlowLayout. LEFT )); //set layout manager add( myButton ); //add components add( label ); label .setPreferredSize( new Dimension(60, 10)); myButton .addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { count ++; label .setText( "Count: " + count ); } }); pack(); setVisible( true ); } public static void main(String args) { try { UIManager. setLookAndFeel (UIManager. getSystemLookAndFeelClassName ()); } catch (Exception exc) {} new Intro(); } } Brief Example Revisited 5 import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Intro extends JFrame { private int count = 0; private JButton myButton = new JButton( "Push Me!" ); private JLabel label = new JLabel("Count: " + count); public Intro() { setDefaultCloseOperation(JFrame. EXIT_ON_CLOSE ); setLayout(new FlowLayout(FlowLayout. LEFT )); //set layout manager add(myButton); //add components add(label); label.setPreferredSize(new Dimension(60, 10)); myButton .addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { count ++; label .setText( "Count: " + count ); } }); pack(); setVisible(true); } public static void main(String args) { try { UIManager. setLookAndFeel (UIManager. getSystemLookAndFeelClassName ()); } catch (Exception exc) {} new Intro(); } } Brief Example Revisited...
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This note was uploaded on 11/20/2008 for the course COM S 211 taught by Professor Kozen during the Spring '06 term at Cornell.

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L19cs211sp07-6up - GUI Dynamics Lecture 19 CS211 – Spring...

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