SumUppublic class SumUp extends Applet | SumUp is a simple applet that adds up some numbers.
This version is for JDK 1.0 and later; code for 1.1 is present
but commented out.
To make this ready for production, we should implement a little
language either in HTML PARAMs, such as
<PARAM NAME=title1 value="Option One">
<PARAM NAME=values1 value="0|100|200|300|400">
<PARAM NAME=title1 value="Option Two">
<PARAM NAME=values1 value="0|400|600|800|1000">
or
in a configuration file which we download and parse (see
TreeLink.java in this directory) or load as a Properties file
(see MenuIntl.java) - note that as of today we can't load
Properties files into an Applet for some reason.
Also, of course, the URL to go to should be a PARAM.
Not to mention the colors (see ColorName and/or XColor). |
| Fields Summary |
|---|
| protected Choice[] | csThe array of Choice items | | protected int | numChoicesHow many are actually in the array. | | protected Label | resultFieldThe result of the summation | | protected Button | sendButtonThe pushbutton to send the form in |
| Methods Summary |
|---|
| public boolean | action(java.awt.Event e, java.lang.Object name)action() is called when a "high level" action happens
(like the user pushing a Button!) in one of the components
added to this Applet. In JDK1.1 this would be actionPerformed(),
but the customer needed this Applet to work on the Internet at
a time when many users' browsers were still at JDK1.0. // 1.0
int total = 0;
for (int i=0; i<numChoices; i++) {
String text = cs[i].getSelectedItem();
// System.err.println("Selection " + i + " = " + text);
int value = Integer.parseInt(text);
total += value;
}
resultField.setText(Integer.toString(total));
// Now, if that was the Send button, do it.
if (sendButton == e.target) {
try {
URL myNewURL = new URL(
"http://server/cgi-bin/credit?SUM=" + total);
// System.out.println("URL = " + myNewURL); // debug...
// "And then a miracle occurs..."
getAppletContext().showDocument(myNewURL);
} catch (Exception err) {
System.err.println("Error!\n" + err);
showStatus("Error, look in Java Console for details!");
}
}
return true; // (1.0) yes, we did something, thank you.
| | public void | init()init() is an Applet method called by the browser to initialize
setBackground(Color.magenta);
// The layout of the Applet is a Grid; always add things in pairs!
setLayout(new GridLayout(0,2));
Choice c;
add(new Label("Option 1"));
add(c = new Choice());
c.addItem("0");
c.addItem("100");
c.addItem("200");
c.addItem("400");
cs[numChoices++] = c;
add(new Label("Option 2"));
add(c = new Choice());
c.addItem("0");
c.addItem("100");
c.addItem("200");
c.addItem("400");
cs[numChoices++] = c;
Panel p = new Panel();
p.setBackground(Color.pink);
p.add(new Label("Total:"));
p.add(resultField = new Label("000000"));
add(p);
sendButton = new Button("Send it");
add(sendButton); // connect Button into Applet
// Next line needed for 1.1 version
// sendButton.addActionListener(this); // connect it back to Applet
// or, better yet, have its own actionListener separate from that
// used by all the Choice items.
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