Aug 27

Uses a FileDialog to choose the file to display 

DisplayFile.java 
****************
import java.awt.*;
import java.awt.event.*;
import java.io.*;

/** Uses a FileDialog to choose the file to display. 
 ***************
 
public class DisplayFile extends CloseableFrame 
                         implements ActionListener {
                                
  public static void main(String[] args) {
    new DisplayFile();
  }

  private Button loadButton;
  private TextArea fileArea;
  private FileDialog loader;

  public DisplayFile() {
    super("Using FileDialog");
    loadButton = new Button("Display File");
    loadButton.addActionListener(this);
    Panel buttonPanel = new Panel();
    buttonPanel.add(loadButton);
    add(buttonPanel, BorderLayout.SOUTH);
    fileArea = new TextArea();
    add("Center", fileArea);
    loader = new FileDialog(this, "Browse", FileDialog.LOAD);
    // Default file extension: .java.
    loader.setFile("*.java");
    setSize(350, 450);
    setVisible(true);
  }

  /** When the button is clicked, a file dialog is opened. When 
   * the file dialog is closed, load the file it referenced.
   */
  
  public void actionPerformed(ActionEvent event) {
      loader.show();
      displayFile(loader.getFile());
  }

  public void displayFile(String filename) {
    try {
      File file = new File(filename);
      FileInputStream in = new FileInputStream(file);
      int fileLength = (int)file.length();
      byte[] fileContents = new byte[fileLength];
      in.read(fileContents);
      String fileContentsString = new String(fileContents);
      fileArea.setText(fileContentsString);
    } catch(IOException ioe) {
      fileArea.setText("IOError: " + ioe);
    }
  }
}
*************
CloseableFrame.java. 
*************
import java.awt.*;
import java.awt.event.*;

/** A Frame that you can actually quit. Used as the starting 
 *  point for most Java 1.1 graphical applications.
 **********************

public class CloseableFrame extends Frame {
  public CloseableFrame(String title) {
    super(title);
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
  }

  /** Since we are doing something permanent, we need
   *  to call super.processWindowEvent first.
   */
  
  public void processWindowEvent(WindowEvent event) {
    super.processWindowEvent(event); // Handle listeners.
    if (event.getID() == WindowEvent.WINDOW_CLOSING) {
      // If the frame is used in an applet, use dispose().
      System.exit(0);
    }
  }
}

Aug 27

Applet that uses a anonymous nested class to handle mouse events and draw circles. Variation on third approach to event-handling: using inner classes. 

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

/** Draw circles centered where the user clicks.
 *  Uses anonymous inner classes.
 *  


**********************
public class CircleDrawer4 extends Applet {
  public void init() {
    setForeground(Color.blue);
    addMouseListener
      (new MouseAdapter() {
         private int radius = 25;

         public void mousePressed(MouseEvent event) {
           Graphics g = getGraphics();
           g.fillOval(event.getX()-radius,
                      event.getY()-radius,
                      2*radius,
                      2*radius);
         }
      });
  }
}
*******************

Aug 27

Tiny applet that uses CircleListener to handle mouse events. 

import java.applet.Applet;
import java.awt.*;

/** Draw circles centered where the user clicks.
 *  Uses an external listener.
 *  


 ***********
public class CircleDrawer1 extends Applet {
  public void init() {
    setForeground(Color.blue);
    addMouseListener(new CircleListener());
  }
}

Aug 27

Subclass of MouseAdapter 

!!!!!!!!!!!!
ClickListener.java A simple subclass of MouseAdapter that reports where the mouse was pressed. When attached to an applet, look for the report in the Java Console.
!!!!!!!!!!!!
import java.awt.event.*;

/** The listener used by ClickReporter.
 *  


 **************

public class ClickListener extends MouseAdapter {
  public void mousePressed(MouseEvent event) {
    System.out.println("Mouse pressed at (" +
                       event.getX() + "," +
                       event.getY() + ").");
  }
}
<<<<<<<<<<<<<<

Aug 27

Create PopupMenu and add MenuItems 

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
************************
/** Simple demo of pop-up menus. 
 *
 ********************

public class ColorPopupMenu extends Applet
                            implements ActionListener {
 private String[] colorNames =
   { "White", "Light Gray", "Gray", "Dark Gray", "Black" };
  private Color[] colors =
    { Color.white, Color.lightGray, Color.gray,
      Color.darkGray, Color.black };
  private PopupMenu menu;

  /** Create PopupMenu and add MenuItems. */
                              
  public void init() {
    setBackground(Color.gray);
    menu = new PopupMenu("Background Color");
    enableEvents(AWTEvent.MOUSE_EVENT_MASK);
    MenuItem colorName;
    for(int i=0; i

Aug 27

ReverseLabels.java Inherits from CloseableFrame.java and uses ReversibleLabel.java. 

ReverseLabels.java Inherits from CloseableFrame.java and uses ReversibleLabel.java. 
**********************
ReverseLabels.java 
**********************
import java.awt.*;

******************

public class ReverseLabels extends CloseableFrame {
  public static void main(String[] args) {
    new ReverseLabels();
  }

  public ReverseLabels() {
    super("Reversible Labels");
    setLayout(new FlowLayout());
    setBackground(Color.lightGray);
    setFont(new Font("Serif", Font.BOLD, 18));
    ReversibleLabel label1 =
      new ReversibleLabel("Black on White",
                          Color.white, Color.black);
    add(label1);
    ReversibleLabel label2 =
      new ReversibleLabel("White on Black",
                          Color.black, Color.white);
    add(label2);
    pack();
    setVisible(true);
  }
}
/./././././././././.
CloseableFrame.java 
&&&&&&&&&&&&&&&&&&&
import java.awt.*;
import java.awt.event.*;

/** A Frame that you can actually quit. Used as the starting 
 *  point for most Java 1.1 graphical applications.
 *
 *******************
 */

public class CloseableFrame extends Frame {
  public CloseableFrame(String title) {
    super(title);
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
  }

  /** Since we are doing something permanent, we need
   *  to call super.processWindowEvent first.
   */
  
  public void processWindowEvent(WindowEvent event) {
    super.processWindowEvent(event); // Handle listeners.
    if (event.getID() == WindowEvent.WINDOW_CLOSING) {
      // If the frame is used in an applet, use dispose().
      System.exit(0);
    }
  }
}
&&&&&&&&&&&&&&&&&&&&
ReversibleLabel.java. 
&&&&&&&&&&&&&&&&&&&&
import java.awt.*;
import java.awt.event.*;

/** A Label that reverses its background and
 *  foreground colors when the mouse is over it.
 *
 **********************
 
public class ReversibleLabel extends Label {
  public ReversibleLabel(String text,
                         Color bgColor, Color fgColor) {
    super(text);
    MouseAdapter reverser = new MouseAdapter() {
      public void mouseEntered(MouseEvent event) {
        reverseColors();
      }

      public void mouseExited(MouseEvent event) {
        reverseColors(); // or mouseEntered(event);
      }
    };
    addMouseListener(reverser);
    setText(text);
    setBackground(bgColor);
    setForeground(fgColor);
  }

  protected void reverseColors() {
    Color fg = getForeground();
    Color bg = getBackground();
    setForeground(bg);
    setBackground(fg);
  }
}
#############################

Aug 27

TextFields 

import java.applet.Applet;
import java.awt.*;

/** A TextField from each of the four constructors.
 *
 *********************

public class TextFields extends Applet {
  public void init() {
    add(new TextField());
    add(new TextField(30));
    add(new TextField("Initial String"));
    add(new TextField("Initial", 30));
  }
}

Aug 27

ChoiceTest2 

ChoiceTest2.java
/././././././././
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

/***********************/

public class ChoiceTest2 extends Applet 
                         implements ItemListener {
  private Choice choice;

  public void init() {
    setFont(new Font("SansSerif", Font.BOLD, 36));
    choice = new Choice();
    choice.addItem("Choice 1");
    choice.addItem("Choice 2");
    choice.addItem("Choice 3");
    choice.addItemListener(this);
    add(choice);
  }

  public void itemStateChanged(ItemEvent event) {
    Choice choice = (Choice)event.getSource();
    String selection = choice.getSelectedItem();
    if (selection.equals("Choice 1")) {
      doChoice1Action();
    } else if (selection.equals("Choice 2")) {
      doChoice2Action();
    } else if (selection.equals("Choice 3")) {
      doChoice3Action();
    }
  }

  private void doChoice1Action() {
    System.out.println("Choice 1 Action");
  }

  private void doChoice2Action() {
    System.out.println("Choice 2 Action");
  }

  private void doChoice3Action() {
    System.out.println("Choice 3 Action");
  }
}

Aug 27

CheckboxGroups 

CheckboxGroups.java
/./././././././././
/////////////////////
import java.applet.Applet;
import java.awt.*;

////////////////////
 
public class CheckboxGroups extends Applet {
  public void init() {
    setLayout(new GridLayout(4, 2));
    setBackground(Color.lightGray);
    setFont(new Font("Serif", Font.BOLD, 16));
    add(new Label("Flavor", Label.CENTER));
    add(new Label("Toppings", Label.CENTER));
    CheckboxGroup flavorGroup = new CheckboxGroup();
    add(new Checkbox("Vanilla", flavorGroup, true));
    add(new Checkbox("Colored Sprinkles"));
    add(new Checkbox("Chocolate", flavorGroup, false));
    add(new Checkbox("Cashews"));
    add(new Checkbox("Strawberry", flavorGroup, false));
    add(new Checkbox("Kiwi"));
  }
}

Aug 26

A textfield and three buttons arranged by a verticle BoxLayout 

BoxLayoutTest.java A textfield and three buttons arranged by a verticle BoxLayout. Uses WindowUtilities.java and ExitListener.java. 
##################
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/** An example of BoxLayout.
 *
 ***********

public class BoxLayoutTest extends JPanel
                           implements ActionListener{
  BoxLayout layout;
  JButton topButton, middleButton, bottomButton;

  public BoxLayoutTest() {
    layout = new BoxLayout(this, BoxLayout.Y_AXIS);
    setLayout(layout);

    JLabel label = new JLabel("BoxLayout Demo");

    topButton = new JButton("Left Alignment");
    middleButton = new JButton("Center Alignment");
    bottomButton = new JButton("Right Alignment");
    topButton.addActionListener(this);
    middleButton.addActionListener(this);
    bottomButton.addActionListener(this);

    add(label);
    add(topButton);
    add(middleButton);
    add(bottomButton);
    setBackground(Color.white);
  }

  public void actionPerformed(ActionEvent event) {
    if (event.getSource() == topButton) {
      refresh(Component.LEFT_ALIGNMENT);
    } else if (event.getSource() == middleButton) {
      refresh(Component.CENTER_ALIGNMENT);
    } else if (event.getSource() == bottomButton) {
      refresh(Component.RIGHT_ALIGNMENT);
    }
  }

  private void refresh(float alignment){
    topButton.setAlignmentX(alignment);
    middleButton.setAlignmentX(alignment);
    bottomButton.setAlignmentX(alignment);
    revalidate();
    System.out.println("x: "+layout.getLayoutAlignmentX(this));
  }

  public static void main(String[] args) {
    WindowUtilities.setNativeLookAndFeel();
    WindowUtilities.openInJFrame(new BoxLayoutTest(), 300, 135,
                                 "BoxLayoutTest");
  }
}