I have a Java applet called TestColor that does not work. Here is the
code.
TestColor.java code:
import java.awt.*;
import java.applet.*;
public class TestColor extends Applet {
String s1;
public void init() {
Color c;
s1 = getParameter("mycolor");
if (s1.equals("blue"))
c = Color.blue;
else if (s1.equals("red"))
c = Color.red;
else if (s1.equals("green"))
c = Color.green;
else
c = Color.cyan;
setBackground(c); }}
Html code:
<HTML>
<HEAD>
<TITLE>A Simple Program</TITLE>
</HEAD>
<BODY>
<h2>Here is the applet:</h2><br>
<APPLET CODE="TestColor.class" WIDTH=550 HEIGHT=500 alt="white">
<param name="mycolor" value="blue">
Sorry, you aren't running a Java-capable browser.
</APPLET>
</BODY>
</HTML>
If I change mycolor to adjective1 in both files. It works. Could you
kindly try it and tell me why?
When I run it in a debugger, I got this msg:
java.lang.NullPointerException
at TestColor.init(TestColor.java:9)
at sun.applet.AppletPanel.run(AppletPanel.java:378)
at java.lang.Thread.run(Thread.java:595)
Warning: classic VM not supported; client VM will be used.
What is the bug?
You are not checking the return value of getParameter(). If "mycolor" isn't