FileDocCategorySizeDatePackage
AppletButton.javaAPI DocExample5416Sat Sep 12 03:01:00 BST 1998None

AppletButton

public class AppletButton extends Applet implements Runnable

Fields Summary
int
frameNumber
String
windowClass
String
buttonText
String
windowTitle
int
requestedWidth
int
requestedHeight
Button
button
Thread
windowThread
Label
label
boolean
pleaseCreate
Constructors Summary
Methods Summary
public synchronized booleanaction(java.awt.Event event, java.lang.Object what)

        if (event.target instanceof Button) {
            //signal the window thread to build a window
            label.setText("Please wait while the window comes up...");
            pleaseCreate = true;
            notify();
        } 
        return true;
public voidinit()


       
        windowClass = getParameter("WINDOWCLASS");
        if (windowClass == null) {
            windowClass = "TestWindow";
        }

        buttonText = getParameter("BUTTONTEXT");
        if (buttonText == null) {
            buttonText = "Click here to bring up a " + windowClass;
        }

        windowTitle = getParameter("WINDOWTITLE");
        if (windowTitle == null) {
            windowTitle = windowClass;
        }

        String windowWidthString = getParameter("WINDOWWIDTH");
        if (windowWidthString != null) {
            try {
                requestedWidth = Integer.parseInt(windowWidthString);
            } catch (NumberFormatException e) {
                //Use default width.
            }
        }
 
        String windowHeightString = getParameter("WINDOWHEIGHT");
        if (windowHeightString != null) {
            try {
                requestedHeight = Integer.parseInt(windowHeightString);
            } catch (NumberFormatException e) {
                //Use default height.
            }
        }
 
        setLayout(new GridLayout(2,0));
        add(button = new Button(buttonText));
        button.setFont(new Font("Helvetica", Font.PLAIN, 14));

        add(label = new Label("", Label.CENTER));
public synchronized voidrun()

        Class windowClassObject = null;
        Class tmp = null;
        String name = null;
        
        // Make sure the window class exists and is really a Frame.
        // This has the added benefit of pre-loading the class,
        // which makes it much quicker for the first window to come up.
        try {
            windowClassObject = Class.forName(windowClass);
        } catch (Exception e) {
            // The specified class isn't anywhere that we can find.
            label.setText("Can't create window: Couldn't find class "
                              + windowClass);
            button.disable();
            return;
        }

        // Find out whether the class is a Frame.
        for (tmp = windowClassObject, name = tmp.getName();
             !( name.equals("java.lang.Object") ||
                name.equals("java.awt.Frame") ); ) {
            tmp = tmp.getSuperclass();
            name = tmp.getName();
        }
        if ((name == null) || name.equals("java.lang.Object")) {
            //We can't run; ERROR; print status, never bring up window
            label.setText("Can't create window: "
                              + windowClass +
                          " isn't a Frame subclass.");
            button.disable();
            return;
        } else if (name.equals("java.awt.Frame")) { 
            //Everything's OK. Wait until we're asked to create a window.
            while (windowThread != null) {
                while (pleaseCreate == false) {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                    }
                }

                //We've been asked to bring up a window.
                pleaseCreate = false;
                Frame window = null;
                try {
                    window = (Frame)windowClassObject.newInstance();
                } catch (Exception e) {
                    label.setText("Couldn't create instance of class "
                                  + windowClass);
                    button.disable();
                    return;
                }
                if (frameNumber == 1) {
                    window.setTitle(windowTitle);
                } else {
                    window.setTitle(windowTitle + ": " + frameNumber);
                }
                frameNumber++;

                //Set the window's size.
                window.pack();
                if ((requestedWidth > 0) | (requestedHeight > 0)) {
                    window.resize(Math.max(requestedWidth,
                                           window.size().width),
                                  Math.max(requestedHeight,
                                           window.size().height));
                }

                window.show();
                label.setText("");
            }
        }
public voidstart()

        if (windowThread == null) {
            windowThread = new Thread(this, "Bringing Up " + windowClass);
            windowThread.start();
        }