Bruce Eckel's Thinking in Java | Contents | Prev | Next |
//: Button2New.java // Capturing button presses import java.awt.*; import java.awt.event.*; // Must add this import java.applet.*; public class Button2New extends Applet { Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); public void init() { b1.addActionListener(new B1()); b2.addActionListener(new B2()); add(b1); add(b2); } class B1 implements ActionListener { public void actionPerformed(ActionEvent e) { getAppletContext().showStatus("Button 1"); } } class B2 implements ActionListener { public void actionPerformed(ActionEvent e) { getAppletContext().showStatus("Button 2"); } } /* The old way: public boolean action(Event evt, Object arg) { if(evt.target.equals(b1)) getAppletContext().showStatus("Button 1"); else if(evt.target.equals(b2)) getAppletContext().showStatus("Button 2"); // Let the base class handle it: else return super.action(evt, arg); return true; // We've handled it here } */ } ///:~
b1.addActionListener(new B1()); b2.addActionListener(new B2());
Event,
listener interface and add- and remove-methods
|
Components
supporting this event
|
---|---|
ActionEvent
ActionListener addActionListener( ) removeActionListener( ) |
Button,
List,
TextField, MenuItem,
and its derivatives including
CheckboxMenuItem,
Menu,
and
PopupMenu
|
AdjustmentEvent
AdjustmentListener addAdjustmentListener( ) removeAdjustmentListener( ) |
Scrollbar
Anything you create that implements the Adjustable interface |
ComponentEvent
ComponentListener addComponentListener( ) removeComponentListener( ) |
Component
and its derivatives, including
Button,
Canvas,
Checkbox,
Choice,
Container
,
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
Frame
,
Label,
List,
Scrollbar,
TextArea,
and
TextField
|
ContainerEvent
ContainerListener addContainerListener( ) removeContainerListener( ) |
Container
and its derivatives, including
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
and
Frame
|
FocusEvent
FocusListener addFocusListener( ) removeFocusListener( ) |
Component
and its derivatives, including
Button,
Canvas,
Checkbox,
Choice,
Container
,
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
Frame
Label,
List,
Scrollbar,
TextArea,
and
TextField
|
KeyEvent
KeyListener addKeyListener( ) removeKeyListener( ) |
Component
and its derivatives, including
Button,
Canvas,
Checkbox,
Choice,
Container
,
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
Frame
,
Label,
List,
Scrollbar,
TextArea,
and
TextField
|
MouseEvent
(for both clicks and motion)
MouseListener addMouseListener( ) removeMouseListener( ) |
Component
and its derivatives, including
Button,
Canvas,
Checkbox,
Choice,
Container
,
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
Frame
,
Label,
List,
Scrollbar,
TextArea,
and
TextField
|
MouseEvent[58]
(for
both clicks and motion)
MouseMotionListener addMouseMotionListener( ) removeMouseMotionListener( ) |
Component
and its derivatives, including
Button,
Canvas,
Checkbox,
Choice,
Container
,
Panel,
Applet,
ScrollPane,
Window,
Dialog,
FileDialog,
Frame
,
Label,
List,
Scrollbar,
TextArea,
and
TextField
|
WindowEvent
WindowListener addWindowListener( ) removeWindowListener( ) |
Window
and its derivatives, including
Dialog,
FileDialog,
and
Frame
|
ItemEvent
ItemListener addItemListener( ) removeItemListener( ) |
Checkbox,
CheckboxMenuItem,
Choice,
List,
and anything that implements the
ItemSelectable
interface
|
TextEvent
TextListener addTextListener( ) removeTextListener( ) |
Anything
derived from
TextComponent,
including
TextArea
and
TextField
|
Component
type
|
Events
supported by this component
|
---|---|
Adjustable
|
AdjustmentEvent
|
Applet
|
ContainerEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Button
|
ActionEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Canvas
|
FocusEvent,
KeyEvent, MouseEvent, ComponentEvent
|
Checkbox
|
ItemEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
CheckboxMenuItem
|
ActionEvent,
ItemEvent
|
Choice
|
ItemEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Component
|
FocusEvent,
KeyEvent, MouseEvent, ComponentEvent
|
Container
|
ContainerEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Dialog
|
ContainerEvent,
WindowEvent, FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
FileDialog
|
ContainerEvent,
WindowEvent, FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Frame
|
ContainerEvent,
WindowEvent, FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Label
|
FocusEvent,
KeyEvent, MouseEvent, ComponentEvent
|
List
|
ActionEvent,
FocusEvent, KeyEvent, MouseEvent, ItemEvent, ComponentEvent
|
Menu
|
ActionEvent
|
MenuItem
|
ActionEvent
|
Panel
|
ContainerEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
PopupMenu
|
ActionEvent
|
Scrollbar
|
AdjustmentEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
ScrollPane
|
ContainerEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
TextArea
|
TextEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
TextComponent
|
TextEvent,
FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
TextField
|
ActionEvent,
TextEvent, FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Window
|
ContainerEvent,
WindowEvent, FocusEvent, KeyEvent, MouseEvent, ComponentEvent
|
Listener
interface
w/ adapter |
Methods
in interface
|
---|---|
ActionListener
|
actionPerformed(ActionEvent)
|
AdjustmentListener
|
adjustmentValueChanged(
AdjustmentEvent) |
componentHidden(ComponentEvent)
componentShown(ComponentEvent) componentMoved(ComponentEvent) componentResized(ComponentEvent) |
|
componentAdded(ContainerEvent)
componentRemoved(ContainerEvent) |
|
focusGained(FocusEvent)
focusLost(FocusEvent) |
|
keyPressed(KeyEvent)
keyReleased(KeyEvent) keyTyped(KeyEvent) |
|
mouseClicked(MouseEvent)
mouseEntered(MouseEvent) mouseExited(MouseEvent) mousePressed(MouseEvent) mouseReleased(MouseEvent) |
|
mouseDragged(MouseEvent)
mouseMoved(MouseEvent) |
|
windowOpened(WindowEvent)
windowClosing(WindowEvent) windowClosed(WindowEvent) windowActivated(WindowEvent) windowDeactivated(WindowEvent) windowIconified(WindowEvent) windowDeiconified(WindowEvent) |
|
ItemListener
|
itemStateChanged(ItemEvent)
|
TextListener
|
textValueChanged(TextEvent)
|
class MyWindowListener extends WindowAdapter { public void windowClosing(WindowEvent e) { System.exit(0); } }
class MyWindowListener extends WindowAdapter { public void WindowClosing(WindowEvent e) { System.exit(0); } }
with the Java 1.1 AWT
//: Button2NewB.java // An application and an applet import java.awt.*; import java.awt.event.*; // Must add this import java.applet.*; public class Button2NewB extends Applet { Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); TextField t = new TextField(20); public void init() { b1.addActionListener(new B1()); b2.addActionListener(new B2()); add(b1); add(b2); add(t); } class B1 implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText("Button 1"); } } class B2 implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText("Button 2"); } } // To close the application: static class WL extends WindowAdapter { public void windowClosing(WindowEvent e) { System.exit(0); } } // A main() for the application: public static void main(String[] args) { Button2NewB applet = new Button2NewB(); Frame aFrame = new Frame("Button2NewB"); aFrame.addWindowListener(new WL()); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300,200); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
an anonymous class
aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } });
<head><title>Button2NewB Example Applet </title></head> <body> <applet code="Button2NewB.class" archive="Button2NewB.jar" width=200 height=150> </applet> </body>
//: TextNew.java // Text fields with Java 1.1 events import java.awt.*; import java.awt.event.*; import java.applet.*; public class TextNew extends Applet { Button b1 = new Button("Get Text"), b2 = new Button("Set Text"); TextField t1 = new TextField(30), t2 = new TextField(30), t3 = new TextField(30); String s = new String(); public void init() { b1.addActionListener(new B1()); b2.addActionListener(new B2()); t1.addTextListener(new T1()); t1.addActionListener(new T1A()); t1.addKeyListener(new T1K()); add(b1); add(b2); add(t1); add(t2); add(t3); } class T1 implements TextListener { public void textValueChanged(TextEvent e) { t2.setText(t1.getText()); } } class T1A implements ActionListener { private int count = 0; public void actionPerformed(ActionEvent e) { t3.setText("t1 Action Event " + count++); } } class T1K extends KeyAdapter { public void keyTyped(KeyEvent e) { String ts = t1.getText(); if(e.getKeyChar() == KeyEvent.VK_BACK_SPACE) { // Ensure it's not empty: if( ts.length() > 0) { ts = ts.substring(0, ts.length() - 1); t1.setText(ts); } } else t1.setText( t1.getText() + Character.toUpperCase( e.getKeyChar())); t1.setCaretPosition( t1.getText().length()); // Stop regular character from appearing: e.consume(); } } class B1 implements ActionListener { public void actionPerformed(ActionEvent e) { s = t1.getSelectedText(); if(s.length() == 0) s = t1.getText(); t1.setEditable(true); } } class B2 implements ActionListener { public void actionPerformed(ActionEvent e) { t1.setText("Inserted by Button 2: " + s); t1.setEditable(false); } } public static void main(String[] args) { TextNew applet = new TextNew(); Frame aFrame = new Frame("TextNew"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300,200); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
class T1 implements TextListener { public void textValueChanged(TextEvent e) { t2.setText(t1.getText()); } }
//: TextAreaNew.java // Controlling scrollbars with the TextArea // component in Java 1.1 import java.awt.*; import java.awt.event.*; import java.applet.*; public class TextAreaNew extends Applet { Button b1 = new Button("Text Area 1"); Button b2 = new Button("Text Area 2"); Button b3 = new Button("Replace Text"); Button b4 = new Button("Insert Text"); TextArea t1 = new TextArea("t1", 1, 30); TextArea t2 = new TextArea("t2", 4, 30); TextArea t3 = new TextArea("t3", 1, 30, TextArea.SCROLLBARS_NONE); TextArea t4 = new TextArea("t4", 10, 10, TextArea.SCROLLBARS_VERTICAL_ONLY); TextArea t5 = new TextArea("t5", 4, 30, TextArea.SCROLLBARS_HORIZONTAL_ONLY); TextArea t6 = new TextArea("t6", 10, 10, TextArea.SCROLLBARS_BOTH); public void init() { b1.addActionListener(new B1L()); add(b1); add(t1); b2.addActionListener(new B2L()); add(b2); add(t2); b3.addActionListener(new B3L()); add(b3); b4.addActionListener(new B4L()); add(b4); add(t3); add(t4); add(t5); add(t6); } class B1L implements ActionListener { public void actionPerformed(ActionEvent e) { t5.append(t1.getText() + "\n"); } } class B2L implements ActionListener { public void actionPerformed(ActionEvent e) { t2.setText("Inserted by Button 2"); t2.append(": " + t1.getText()); t5.append(t2.getText() + "\n"); } } class B3L implements ActionListener { public void actionPerformed(ActionEvent e) { String s = " Replacement "; t2.replaceRange(s, 3, 3 + s.length()); } } class B4L implements ActionListener { public void actionPerformed(ActionEvent e) { t2.insert(" Inserted ", 10); } } public static void main(String[] args) { TextAreaNew applet = new TextAreaNew(); Frame aFrame = new Frame("TextAreaNew"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300,725); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
//: RadioCheckNew.java // Radio buttons and Check Boxes in Java 1.1 import java.awt.*; import java.awt.event.*; import java.applet.*; public class RadioCheckNew extends Applet { TextField t = new TextField(30); Checkbox[] cb = { new Checkbox("Check Box 1"), new Checkbox("Check Box 2"), new Checkbox("Check Box 3") }; CheckboxGroup g = new CheckboxGroup(); Checkbox cb4 = new Checkbox("four", g, false), cb5 = new Checkbox("five", g, true), cb6 = new Checkbox("six", g, false); public void init() { t.setEditable(false); add(t); ILCheck il = new ILCheck(); for(int i = 0; i < cb.length; i++) { cb[i].addItemListener(il); add(cb[i]); } cb4.addItemListener(new IL4()); cb5.addItemListener(new IL5()); cb6.addItemListener(new IL6()); add(cb4); add(cb5); add(cb6); } // Checking the source: class ILCheck implements ItemListener { public void itemStateChanged(ItemEvent e) { for(int i = 0; i < cb.length; i++) { if(e.getSource().equals(cb[i])) { t.setText("Check box " + (i + 1)); return; } } } } // vs. an individual class for each item: class IL4 implements ItemListener { public void itemStateChanged(ItemEvent e) { t.setText("Radio button four"); } } class IL5 implements ItemListener { public void itemStateChanged(ItemEvent e) { t.setText("Radio button five"); } } class IL6 implements ItemListener { public void itemStateChanged(ItemEvent e) { t.setText("Radio button six"); } } public static void main(String[] args) { RadioCheckNew applet = new RadioCheckNew(); Frame aFrame = new Frame("RadioCheckNew"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300,200); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
//: ChoiceNew.java // Drop-down lists with Java 1.1 import java.awt.*; import java.awt.event.*; import java.applet.*; public class ChoiceNew extends Applet { String[] description = { "Ebullient", "Obtuse", "Recalcitrant", "Brilliant", "Somnescent", "Timorous", "Florid", "Putrescent" }; TextField t = new TextField(100); Choice c = new Choice(); Button b = new Button("Add items"); int count = 0; public void init() { t.setEditable(false); for(int i = 0; i < 4; i++) c.addItem(description[count++]); add(t); add(c); add(b); c.addItemListener(new CL()); b.addActionListener(new BL()); } class CL implements ItemListener { public void itemStateChanged(ItemEvent e) { t.setText("index: " + c.getSelectedIndex() + " " + e.toString()); } } class BL implements ActionListener { public void actionPerformed(ActionEvent e) { if(count < description.length) c.addItem(description[count++]); } } public static void main(String[] args) { ChoiceNew applet = new ChoiceNew(); Frame aFrame = new Frame("ChoiceNew"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(750,100); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
//: ListNew.java // Java 1.1 Lists are easier to use import java.awt.*; import java.awt.event.*; import java.applet.*; public class ListNew extends Applet { String[] flavors = { "Chocolate", "Strawberry", "Vanilla Fudge Swirl", "Mint Chip", "Mocha Almond Fudge", "Rum Raisin", "Praline Cream", "Mud Pie" }; // Show 6 items, allow multiple selection: List lst = new List(6, true); TextArea t = new TextArea(flavors.length, 30); Button b = new Button("test"); int count = 0; public void init() { t.setEditable(false); for(int i = 0; i < 4; i++) lst.addItem(flavors[count++]); add(t); add(lst); add(b); lst.addItemListener(new LL()); b.addActionListener(new BL()); } class LL implements ItemListener { public void itemStateChanged(ItemEvent e) { t.setText(""); String[] items = lst.getSelectedItems(); for(int i = 0; i < items.length; i++) t.append(items[i] + "\n"); } } class BL implements ActionListener { public void actionPerformed(ActionEvent e) { if(count < flavors.length) lst.addItem(flavors[count++], 0); } } public static void main(String[] args) { ListNew applet = new ListNew(); Frame aFrame = new Frame("ListNew"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300,200); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
//: MenuNew.java // Menus in Java 1.1 import java.awt.*; import java.awt.event.*; public class MenuNew extends Frame { String[] flavors = { "Chocolate", "Strawberry", "Vanilla Fudge Swirl", "Mint Chip", "Mocha Almond Fudge", "Rum Raisin", "Praline Cream", "Mud Pie" }; TextField t = new TextField("No flavor", 30); MenuBar mb1 = new MenuBar(); Menu f = new Menu("File"); Menu m = new Menu("Flavors"); Menu s = new Menu("Safety"); // Alternative approach: CheckboxMenuItem[] safety = { new CheckboxMenuItem("Guard"), new CheckboxMenuItem("Hide") }; MenuItem[] file = { // No menu shortcut: new MenuItem("Open"), // Adding a menu shortcut is very simple: new MenuItem("Exit", new MenuShortcut(KeyEvent.VK_E)) }; // A second menu bar to swap to: MenuBar mb2 = new MenuBar(); Menu fooBar = new Menu("fooBar"); MenuItem[] other = { new MenuItem("Foo"), new MenuItem("Bar"), new MenuItem("Baz"), }; // Initialization code: { ML ml = new ML(); CMIL cmil = new CMIL(); safety[0].setActionCommand("Guard"); safety[0].addItemListener(cmil); safety[1].setActionCommand("Hide"); safety[1].addItemListener(cmil); file[0].setActionCommand("Open"); file[0].addActionListener(ml); file[1].setActionCommand("Exit"); file[1].addActionListener(ml); other[0].addActionListener(new FooL()); other[1].addActionListener(new BarL()); other[2].addActionListener(new BazL()); } Button b = new Button("Swap Menus"); public MenuNew() { FL fl = new FL(); for(int i = 0; i < flavors.length; i++) { MenuItem mi = new MenuItem(flavors[i]); mi.addActionListener(fl); m.add(mi); // Add separators at intervals: if((i+1) % 3 == 0) m.addSeparator(); } for(int i = 0; i < safety.length; i++) s.add(safety[i]); f.add(s); for(int i = 0; i < file.length; i++) f.add(file[i]); mb1.add(f); mb1.add(m); setMenuBar(mb1); t.setEditable(false); add(t, BorderLayout.CENTER); // Set up the system for swapping menus: b.addActionListener(new BL()); add(b, BorderLayout.NORTH); for(int i = 0; i < other.length; i++) fooBar.add(other[i]); mb2.add(fooBar); } class BL implements ActionListener { public void actionPerformed(ActionEvent e) { MenuBar m = getMenuBar(); if(m == mb1) setMenuBar(mb2); else if (m == mb2) setMenuBar(mb1); } } class ML implements ActionListener { public void actionPerformed(ActionEvent e) { MenuItem target = (MenuItem)e.getSource(); String actionCommand = target.getActionCommand(); if(actionCommand.equals("Open")) { String s = t.getText(); boolean chosen = false; for(int i = 0; i < flavors.length; i++) if(s.equals(flavors[i])) chosen = true; if(!chosen) t.setText("Choose a flavor first!"); else t.setText("Opening "+ s +". Mmm, mm!"); } else if(actionCommand.equals("Exit")) { dispatchEvent( new WindowEvent(MenuNew.this, WindowEvent.WINDOW_CLOSING)); } } } class FL implements ActionListener { public void actionPerformed(ActionEvent e) { MenuItem target = (MenuItem)e.getSource(); t.setText(target.getLabel()); } } // Alternatively, you can create a different // class for each different MenuItem. Then you // Don't have to figure out which one it is: class FooL implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText("Foo selected"); } } class BarL implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText("Bar selected"); } } class BazL implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText("Baz selected"); } } class CMIL implements ItemListener { public void itemStateChanged(ItemEvent e) { CheckboxMenuItem target = (CheckboxMenuItem)e.getSource(); String actionCommand = target.getActionCommand(); if(actionCommand.equals("Guard")) t.setText("Guard the Ice Cream! " + "Guarding is " + target.getState()); else if(actionCommand.equals("Hide")) t.setText("Hide the Ice Cream! " + "Is it cold? " + target.getState()); } } public static void main(String[] args) { MenuNew f = new MenuNew(); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); f.setSize(300,200); f.setVisible(true); } } ///:~
//: ToeTestNew.java // Demonstration of dialog boxes // and creating your own components import java.awt.*; import java.awt.event.*; public class ToeTestNew extends Frame { TextField rows = new TextField("3"); TextField cols = new TextField("3"); public ToeTestNew() { setTitle("Toe Test"); Panel p = new Panel(); p.setLayout(new GridLayout(2,2)); p.add(new Label("Rows", Label.CENTER)); p.add(rows); p.add(new Label("Columns", Label.CENTER)); p.add(cols); add(p, BorderLayout.NORTH); Button b = new Button("go"); b.addActionListener(new BL()); add(b, BorderLayout.SOUTH); } static final int BLANK = 0; static final int XX = 1; static final int OO = 2; class ToeDialog extends Dialog { // w = number of cells wide // h = number of cells high int turn = XX; // Start with x's turn public ToeDialog(int w, int h) { super(ToeTestNew.this, "The game itself", false); setLayout(new GridLayout(w, h)); for(int i = 0; i < w * h; i++) add(new ToeButton()); setSize(w * 50, h * 50); addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e){ dispose(); } }); } class ToeButton extends Canvas { int state = BLANK; ToeButton() { addMouseListener(new ML()); } public void paint(Graphics g) { int x1 = 0; int y1 = 0; int x2 = getSize().width - 1; int y2 = getSize().height - 1; g.drawRect(x1, y1, x2, y2); x1 = x2/4; y1 = y2/4; int wide = x2/2; int high = y2/2; if(state == XX) { g.drawLine(x1, y1, x1 + wide, y1 + high); g.drawLine(x1, y1 + high, x1 + wide, y1); } if(state == OO) { g.drawOval(x1, y1, x1 + wide/2, y1 + high/2); } } class ML extends MouseAdapter { public void mousePressed(MouseEvent e) { if(state == BLANK) { state = turn; turn = (turn == XX ? OO : XX); } else state = (state == XX ? OO : XX); repaint(); } } } } class BL implements ActionListener { public void actionPerformed(ActionEvent e) { Dialog d = new ToeDialog( Integer.parseInt(rows.getText()), Integer.parseInt(cols.getText())); d.show(); } } public static void main(String[] args) { Frame f = new ToeTestNew(); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); f.setSize(200,100); f.setVisible(true); } } ///:~
//: FileDialogNew.java // Demonstration of File dialog boxes import java.awt.*; import java.awt.event.*; public class FileDialogNew extends Frame { TextField filename = new TextField(); TextField directory = new TextField(); Button open = new Button("Open"); Button save = new Button("Save"); public FileDialogNew() { setTitle("File Dialog Test"); Panel p = new Panel(); p.setLayout(new FlowLayout()); open.addActionListener(new OpenL()); p.add(open); save.addActionListener(new SaveL()); p.add(save); add(p, BorderLayout.SOUTH); directory.setEditable(false); filename.setEditable(false); p = new Panel(); p.setLayout(new GridLayout(2,1)); p.add(filename); p.add(directory); add(p, BorderLayout.NORTH); } class OpenL implements ActionListener { public void actionPerformed(ActionEvent e) { // Two arguments, defaults to open file: FileDialog d = new FileDialog( FileDialogNew.this, "What file do you want to open?"); d.setFile("*.java"); d.setDirectory("."); // Current directory d.show(); String yourFile = "*.*"; if((yourFile = d.getFile()) != null) { filename.setText(yourFile); directory.setText(d.getDirectory()); } else { filename.setText("You pressed cancel"); directory.setText(""); } } } class SaveL implements ActionListener { public void actionPerformed(ActionEvent e) { FileDialog d = new FileDialog( FileDialogNew.this, "What file do you want to save?", FileDialog.SAVE); d.setFile("*.java"); d.setDirectory("."); d.show(); String saveFile; if((saveFile = d.getFile()) != null) { filename.setText(saveFile); directory.setText(d.getDirectory()); } else { filename.setText("You pressed cancel"); directory.setText(""); } } } public static void main(String[] args) { Frame f = new FileDialogNew(); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); f.setSize(250,110); f.setVisible(true); } } ///:~
//: DynamicEvents.java // The new Java 1.1 event model allows you to // change event behavior dynamically. Also // demonstrates multiple actions for an event. import java.awt.*; import java.awt.event.*; import java.util.*; public class DynamicEvents extends Frame { Vector v = new Vector(); int i = 0; Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); public DynamicEvents() { setLayout(new FlowLayout()); b1.addActionListener(new B()); b1.addActionListener(new B1()); b2.addActionListener(new B()); b2.addActionListener(new B2()); add(b1); add(b2); } class B implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("A button was pressed"); } } class CountListener implements ActionListener { int index; public CountListener(int i) { index = i; } public void actionPerformed(ActionEvent e) { System.out.println( "Counted Listener " + index); } } class B1 implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("Button 1 pressed"); ActionListener a = new CountListener(i++); v.addElement(a); b2.addActionListener(a); } } class B2 implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("Button 2 pressed"); int end = v.size() -1; if(end >= 0) { b2.removeActionListener( (ActionListener)v.elementAt(end)); v.removeElementAt(end); } } } public static void main(String[] args) { Frame f = new DynamicEvents(); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e){ System.exit(0); } }); f.setSize(300,200); f.show(); } } ///:~
from UI logic
//: Separation.java // Separating GUI logic and business objects import java.awt.*; import java.awt.event.*; import java.applet.*; class BusinessLogic { private int modifier; BusinessLogic(int mod) { modifier = mod; } public void setModifier(int mod) { modifier = mod; } public int getModifier() { return modifier; } // Some business operations: public int calculation1(int arg) { return arg * modifier; } public int calculation2(int arg) { return arg + modifier; } } public class Separation extends Applet { TextField t = new TextField(20), mod = new TextField(20); BusinessLogic bl = new BusinessLogic(2); Button calc1 = new Button("Calculation 1"), calc2 = new Button("Calculation 2"); public void init() { add(t); calc1.addActionListener(new Calc1L()); calc2.addActionListener(new Calc2L()); add(calc1); add(calc2); mod.addTextListener(new ModL()); add(new Label("Modifier:")); add(mod); } static int getValue(TextField tf) { try { return Integer.parseInt(tf.getText()); } catch(NumberFormatException e) { return 0; } } class Calc1L implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText(Integer.toString( bl.calculation1(getValue(t)))); } } class Calc2L implements ActionListener { public void actionPerformed(ActionEvent e) { t.setText(Integer.toString( bl.calculation2(getValue(t)))); } } class ModL implements TextListener { public void textValueChanged(TextEvent e) { bl.setModifier(getValue(mod)); } } public static void main(String[] args) { Separation applet = new Separation(); Frame aFrame = new Frame("Separation"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(200,200); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~
//: GoodIdea.java // The best way to design classes using the new // Java 1.1 event model: use an inner class for // each different event. This maximizes // flexibility and modularity. import java.awt.*; import java.awt.event.*; import java.util.*; public class GoodIdea extends Frame { Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); public GoodIdea() { setLayout(new FlowLayout()); b1.addActionListener(new B1L()); b2.addActionListener(new B2L()); add(b1); add(b2); } public class B1L implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("Button 1 pressed"); } } public class B2L implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("Button 2 pressed"); } } public static void main(String[] args) { Frame f = new GoodIdea(); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e){ System.out.println("Window Closing"); System.exit(0); } }); f.setSize(300,200); f.setVisible(true); } } ///:~
//: BadIdea1.java // Some literature recommends this approach, // but it's missing the point of the new event // model in Java 1.1 import java.awt.*; import java.awt.event.*; import java.util.*; public class BadIdea1 extends Frame implements ActionListener, WindowListener { Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); public BadIdea1() { setLayout(new FlowLayout()); addWindowListener(this); b1.addActionListener(this); b2.addActionListener(this); add(b1); add(b2); } public void actionPerformed(ActionEvent e) { Object source = e.getSource(); if(source == b1) System.out.println("Button 1 pressed"); else if(source == b2) System.out.println("Button 2 pressed"); else System.out.println("Something else"); } public void windowClosing(WindowEvent e) { System.out.println("Window Closing"); System.exit(0); } public void windowClosed(WindowEvent e) {} public void windowDeiconified(WindowEvent e) {} public void windowIconified(WindowEvent e) {} public void windowActivated(WindowEvent e) {} public void windowDeactivated(WindowEvent e) {} public void windowOpened(WindowEvent e) {} public static void main(String[] args) { Frame f = new BadIdea1(); f.setSize(300,200); f.setVisible(true); } } ///:~
addWindowListener(this); b1.addActionListener(this); b2.addActionListener(this);
//: BadIdea2.java // An improvement over BadIdea1.java, since it // uses the WindowAdapter as an inner class // instead of implementing all the methods of // WindowListener, but still misses the // valuable modularity of inner classes import java.awt.*; import java.awt.event.*; import java.util.*; public class BadIdea2 extends Frame implements ActionListener { Button b1 = new Button("Button 1"), b2 = new Button("Button 2"); public BadIdea2() { setLayout(new FlowLayout()); addWindowListener(new WL()); b1.addActionListener(this); b2.addActionListener(this); add(b1); add(b2); } public void actionPerformed(ActionEvent e) { Object source = e.getSource(); if(source == b1) System.out.println("Button 1 pressed"); else if(source == b2) System.out.println("Button 2 pressed"); else System.out.println("Something else"); } class WL extends WindowAdapter { public void windowClosing(WindowEvent e) { System.out.println("Window Closing"); System.exit(0); } } public static void main(String[] args) { Frame f = new BadIdea2(); f.setSize(300,200); f.setVisible(true); } } ///:~
//: GoodTechnique.java // Your first choice when overriding components // should be to install listeners. The code is // much safer, more modular and maintainable. import java.awt.*; import java.awt.event.*; class Display { public static final int EVENT = 0, COMPONENT = 1, MOUSE = 2, MOUSE_MOVE = 3, FOCUS = 4, KEY = 5, ACTION = 6, LAST = 7; public String[] evnt; Display() { evnt = new String[LAST]; for(int i = 0; i < LAST; i++) evnt[i] = new String(); } public void show(Graphics g) { for(int i = 0; i < LAST; i++) g.drawString(evnt[i], 0, 10 * i + 10); } } class EnabledPanel extends Panel { Color c; int id; Display display = new Display(); public EnabledPanel(int i, Color mc) { id = i; c = mc; setLayout(new BorderLayout()); add(new MyButton(), BorderLayout.SOUTH); addComponentListener(new CL()); addFocusListener(new FL()); addKeyListener(new KL()); addMouseListener(new ML()); addMouseMotionListener(new MML()); } // To eliminate flicker: public void update(Graphics g) { paint(g); } public void paint(Graphics g) { g.setColor(c); Dimension s = getSize(); g.fillRect(0, 0, s.width, s.height); g.setColor(Color.black); display.show(g); } // Don't need to enable anything for this: public void processEvent(AWTEvent e) { display.evnt[Display.EVENT]= e.toString(); repaint(); super.processEvent(e); } class CL implements ComponentListener { public void componentMoved(ComponentEvent e){ display.evnt[Display.COMPONENT] = "Component moved"; repaint(); } public void componentResized(ComponentEvent e) { display.evnt[Display.COMPONENT] = "Component resized"; repaint(); } public void componentHidden(ComponentEvent e) { display.evnt[Display.COMPONENT] = "Component hidden"; repaint(); } public void componentShown(ComponentEvent e){ display.evnt[Display.COMPONENT] = "Component shown"; repaint(); } } class FL implements FocusListener { public void focusGained(FocusEvent e) { display.evnt[Display.FOCUS] = "FOCUS gained"; repaint(); } public void focusLost(FocusEvent e) { display.evnt[Display.FOCUS] = "FOCUS lost"; repaint(); } } class KL implements KeyListener { public void keyPressed(KeyEvent e) { display.evnt[Display.KEY] = "KEY pressed: "; showCode(e); } public void keyReleased(KeyEvent e) { display.evnt[Display.KEY] = "KEY released: "; showCode(e); } public void keyTyped(KeyEvent e) { display.evnt[Display.KEY] = "KEY typed: "; showCode(e); } void showCode(KeyEvent e) { int code = e.getKeyCode(); display.evnt[Display.KEY] += KeyEvent.getKeyText(code); repaint(); } } class ML implements MouseListener { public void mouseClicked(MouseEvent e) { requestFocus(); // Get FOCUS on click display.evnt[Display.MOUSE] = "MOUSE clicked"; showMouse(e); } public void mousePressed(MouseEvent e) { display.evnt[Display.MOUSE] = "MOUSE pressed"; showMouse(e); } public void mouseReleased(MouseEvent e) { display.evnt[Display.MOUSE] = "MOUSE released"; showMouse(e); } public void mouseEntered(MouseEvent e) { display.evnt[Display.MOUSE] = "MOUSE entered"; showMouse(e); } public void mouseExited(MouseEvent e) { display.evnt[Display.MOUSE] = "MOUSE exited"; showMouse(e); } void showMouse(MouseEvent e) { display.evnt[Display.MOUSE] += ", x = " + e.getX() + ", y = " + e.getY(); repaint(); } } class MML implements MouseMotionListener { public void mouseDragged(MouseEvent e) { display.evnt[Display.MOUSE_MOVE] = "MOUSE dragged"; showMouse(e); } public void mouseMoved(MouseEvent e) { display.evnt[Display.MOUSE_MOVE] = "MOUSE moved"; showMouse(e); } void showMouse(MouseEvent e) { display.evnt[Display.MOUSE_MOVE] += ", x = " + e.getX() + ", y = " + e.getY(); repaint(); } } } class MyButton extends Button { int clickCounter; String label = ""; public MyButton() { addActionListener(new AL()); } public void paint(Graphics g) { g.setColor(Color.green); Dimension s = getSize(); g.fillRect(0, 0, s.width, s.height); g.setColor(Color.black); g.drawRect(0, 0, s.width - 1, s.height - 1); drawLabel(g); } private void drawLabel(Graphics g) { FontMetrics fm = g.getFontMetrics(); int width = fm.stringWidth(label); int height = fm.getHeight(); int ascent = fm.getAscent(); int leading = fm.getLeading(); int horizMargin = (getSize().width - width)/2; int verMargin = (getSize().height - height)/2; g.setColor(Color.red); g.drawString(label, horizMargin, verMargin + ascent + leading); } class AL implements ActionListener { public void actionPerformed(ActionEvent e) { clickCounter++; label = "click #" + clickCounter + " " + e.toString(); repaint(); } } } public class GoodTechnique extends Frame { GoodTechnique() { setLayout(new GridLayout(2,2)); add(new EnabledPanel(1, Color.cyan)); add(new EnabledPanel(2, Color.lightGray)); add(new EnabledPanel(3, Color.yellow)); } public static void main(String[] args) { Frame f = new GoodTechnique(); f.setTitle("Good Technique"); f.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e){ System.out.println(e); System.out.println("Window Closing"); System.exit(0); } }); f.setSize(700,700); f.setVisible(true); } } ///:~
public void update(Graphics g) { paint(g); }
//: BadTechnique.java // It's possible to override components this way, // but the listener approach is much better, so // why would you? import java.awt.*; import java.awt.event.*; class Display { public static final int EVENT = 0, COMPONENT = 1, MOUSE = 2, MOUSE_MOVE = 3, FOCUS = 4, KEY = 5, ACTION = 6, LAST = 7; public String[] evnt; Display() { evnt = new String[LAST]; for(int i = 0; i < LAST; i++) evnt[i] = new String(); } public void show(Graphics g) { for(int i = 0; i < LAST; i++) g.drawString(evnt[i], 0, 10 * i + 10); } } class EnabledPanel extends Panel { Color c; int id; Display display = new Display(); public EnabledPanel(int i, Color mc) { id = i; c = mc; setLayout(new BorderLayout()); add(new MyButton(), BorderLayout.SOUTH); // Type checking is lost. You can enable and // process events that the component doesn't // capture: enableEvents( // Panel doesn't handle these: AWTEvent.ACTION_EVENT_MASK | AWTEvent.ADJUSTMENT_EVENT_MASK | AWTEvent.ITEM_EVENT_MASK | AWTEvent.TEXT_EVENT_MASK | AWTEvent.WINDOW_EVENT_MASK | // Panel can handle these: AWTEvent.COMPONENT_EVENT_MASK | AWTEvent.FOCUS_EVENT_MASK | AWTEvent.KEY_EVENT_MASK | AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK | AWTEvent.CONTAINER_EVENT_MASK); // You can enable an event without // overriding its process method. } // To eliminate flicker: public void update(Graphics g) { paint(g); } public void paint(Graphics g) { g.setColor(c); Dimension s = getSize(); g.fillRect(0, 0, s.width, s.height); g.setColor(Color.black); display.show(g); } public void processEvent(AWTEvent e) { display.evnt[Display.EVENT]= e.toString(); repaint(); super.processEvent(e); } public void processComponentEvent(ComponentEvent e) { switch(e.getID()) { case ComponentEvent.COMPONENT_MOVED: display.evnt[Display.COMPONENT] = "Component moved"; break; case ComponentEvent.COMPONENT_RESIZED: display.evnt[Display.COMPONENT] = "Component resized"; break; case ComponentEvent.COMPONENT_HIDDEN: display.evnt[Display.COMPONENT] = "Component hidden"; break; case ComponentEvent.COMPONENT_SHOWN: display.evnt[Display.COMPONENT] = "Component shown"; break; default: } repaint(); // Must always remember to call the "super" // version of whatever you override: super.processComponentEvent(e); } public void processFocusEvent(FocusEvent e) { switch(e.getID()) { case FocusEvent.FOCUS_GAINED: display.evnt[Display.FOCUS] = "FOCUS gained"; break; case FocusEvent.FOCUS_LOST: display.evnt[Display.FOCUS] = "FOCUS lost"; break; default: } repaint(); super.processFocusEvent(e); } public void processKeyEvent(KeyEvent e) { switch(e.getID()) { case KeyEvent.KEY_PRESSED: display.evnt[Display.KEY] = "KEY pressed: "; break; case KeyEvent.KEY_RELEASED: display.evnt[Display.KEY] = "KEY released: "; break; case KeyEvent.KEY_TYPED: display.evnt[Display.KEY] = "KEY typed: "; break; default: } int code = e.getKeyCode(); display.evnt[Display.KEY] += KeyEvent.getKeyText(code); repaint(); super.processKeyEvent(e); } public void processMouseEvent(MouseEvent e) { switch(e.getID()) { case MouseEvent.MOUSE_CLICKED: requestFocus(); // Get FOCUS on click display.evnt[Display.MOUSE] = "MOUSE clicked"; break; case MouseEvent.MOUSE_PRESSED: display.evnt[Display.MOUSE] = "MOUSE pressed"; break; case MouseEvent.MOUSE_RELEASED: display.evnt[Display.MOUSE] = "MOUSE released"; break; case MouseEvent.MOUSE_ENTERED: display.evnt[Display.MOUSE] = "MOUSE entered"; break; case MouseEvent.MOUSE_EXITED: display.evnt[Display.MOUSE] = "MOUSE exited"; break; default: } display.evnt[Display.MOUSE] += ", x = " + e.getX() + ", y = " + e.getY(); repaint(); super.processMouseEvent(e); } public void processMouseMotionEvent(MouseEvent e) { switch(e.getID()) { case MouseEvent.MOUSE_DRAGGED: display.evnt[Display.MOUSE_MOVE] = "MOUSE dragged"; break; case MouseEvent.MOUSE_MOVED: display.evnt[Display.MOUSE_MOVE] = "MOUSE moved"; break; default: } display.evnt[Display.MOUSE_MOVE] += ", x = " + e.getX() + ", y = " + e.getY(); repaint(); super.processMouseMotionEvent(e); } } class MyButton extends Button { int clickCounter; String label = ""; public MyButton() { enableEvents(AWTEvent.ACTION_EVENT_MASK); } public void paint(Graphics g) { g.setColor(Color.green); Dimension s = getSize(); g.fillRect(0, 0, s.width, s.height); g.setColor(Color.black); g.drawRect(0, 0, s.width - 1, s.height - 1); drawLabel(g); } private void drawLabel(Graphics g) { FontMetrics fm = g.getFontMetrics(); int width = fm.stringWidth(label); int height = fm.getHeight(); int ascent = fm.getAscent(); int leading = fm.getLeading(); int horizMargin = (getSize().width - width)/2; int verMargin = (getSize().height - height)/2; g.setColor(Color.red); g.drawString(label, horizMargin, verMargin + ascent + leading); } public void processActionEvent(ActionEvent e) { clickCounter++; label = "click #" + clickCounter + " " + e.toString(); repaint(); super.processActionEvent(e); } } public class BadTechnique extends Frame { BadTechnique() { setLayout(new GridLayout(2,2)); add(new EnabledPanel(1, Color.cyan)); add(new EnabledPanel(2, Color.lightGray)); add(new EnabledPanel(3, Color.yellow)); // You can also do it for Windows: enableEvents(AWTEvent.WINDOW_EVENT_MASK); } public void processWindowEvent(WindowEvent e) { System.out.println(e); if(e.getID() == WindowEvent.WINDOW_CLOSING) { System.out.println("Window Closing"); System.exit(0); } } public static void main(String[] args) { Frame f = new BadTechnique(); f.setTitle("Bad Technique"); f.setSize(700,700); f.setVisible(true); } } ///:~