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BUG 15
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BUGCD1998_06.ISO
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aplic
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jbuilder
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jhelp.z
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AppletButton.java
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1997-07-30
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//TO DO: Close all windows when you leave the page?
import java.awt.*;
import java.util.*;
import java.applet.Applet;
public class AppletButton extends Applet implements Runnable {
int frameNumber = 1;
String windowClass;
String buttonText;
String windowTitle;
int requestedWidth = 0;
int requestedHeight = 0;
Button button;
Thread windowThread;
Label label;
boolean pleaseCreate = false;
public void init() {
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 void start() {
if (windowThread == null) {
windowThread = new Thread(this, "Bringing Up " + windowClass);
windowThread.start();
}
}
public synchronized void run() {
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 synchronized boolean action(Event event, 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;
}
}
class TestWindow extends Frame {
public TestWindow() {
resize(300, 300);
}
}