Java Reference
In-Depth Information
make use of them. (The
appletviewer
application in the JDK does call these meth-
ods, however.)
Example 15−5: ColorScribble.java
package com.davidflanagan.examples.applet;
import java.applet.*;
import java.awt.*;
/**
* A version of the Scribble applet that reads two applet parameters
* to set the foreground and background colors. It also returns
* information about itself when queried.
**/
public class ColorScribble extends Scribble {
// Read in two color parameters and set the colors.
public void init() {
super.init(); // Let the superclass initialize itself
Color foreground = getColorParameter("foreground");
Color background = getColorParameter("background");
if (foreground != null) this.setForeground(foreground);
if (background != null) this.setBackground(background);
}
// Read the specified parameter. Interpret it as a hexadecimal
// number of the form RRGGBB and convert it to a color.
protected Color getColorParameter(String name) {
String value = this.getParameter(name);
try { return new Color(Integer.parseInt(value, 16)); }
catch (Exception e) { return null; }
}
// Return information suitable for display in an About dialog box.
public String getAppletInfo() {
return "ColorScribble v. 0.03. Written by David Flanagan.";
}
// Return info about the supported parameters. Web browsers and applet
// viewers should display this information, and may also allow users to
// set the parameter values.
public String[][] getParameterInfo() { return info; }
// Here's the information that getParameterInfo() returns.
// It is an array of arrays of strings describing each parameter.
// Format: parameter name, parameter type, parameter description
private String[][] info = {
{"foreground", "hexadecimal color value", "foreground color"},
{"background", "hexadecimal color value", "background color"}
};
}
The following HTML fragment references the applet, and demonstrates how
parameter values can be set with the
<PARAM>
tag:
<applet code="com.davidflanagan.examples.applet.ColorScribble.class"
codebase="../../../../" width=400 height=400>
<param name="foreground" value="FF0000">
<param name="background" value="CCFFCC">
</applet>
