Adding two integer values by passing parameters through an applet

java applet parameter-passing appletviewer
Salman picture Salman · May 1, 2013 · Viewed 7.1k times · Source

The following java program gets compiled successfully but when I try to run it using appletviewer, I get the following (in command prompt) with a message "applet not initialized" in the applet window.

import java.applet.*;
import java.awt.*;
/*
<applet code="ParamDemo" width="300" height="300">
<param name="first" value="20">
<param name="second" value="30">
</applet>
*/
class ParamDemo extends Applet
{
int x,y,sum;
public void init()
{
x=Integer.parseInt(getParameter("first"));
y=Integer.parseInt(getParameter("second"));
}
public void paint(Graphics g)
{
sum=x+y;
g.drawString("Total Sum is"+sum,100,100);
}
}

in the Command prompt -

C:\Documents and Settings\Salman\Desktop>javac ParamDemo.java

C:\Documents and Settings\Salman\Desktop>appletviewer ParamDemo.java
load: ParamDemo is not public or has no public constructor.
java.lang.IllegalAccessException: Class sun.applet.AppletPanel can not access a
member of class ParamDemo with modifiers ""
        at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:95)
        at java.lang.Class.newInstance0(Class.java:368)
        at java.lang.Class.newInstance(Class.java:327)
        at sun.applet.AppletPanel.createApplet(AppletPanel.java:793)
        at sun.applet.AppletPanel.runLoader(AppletPanel.java:722)
        at sun.applet.AppletPanel.run(AppletPanel.java:379)
        at java.lang.Thread.run(Thread.java:722)

I am unable to figure out the problem ...

Any help would be appreciated !

Answer

fjf2002 picture fjf2002 · May 1, 2013

ParamDemo is not public

indicates you shall write public before class ParamDemo extends ....

If no access modifier (such as public) is given for class, it is only accessible within the same package - no wonder appletviewer has problems with it.

An explicit constructor shouldn't be neccessary.

Related questions

Unsupported major.minor version 52.0

Pictures: Command Prompt showing versions Picture of error Hello.java import java.applet.Applet; import java.awt.*; public class Hello extends Applet { // Java applet to draw "Hello World" public void paint (Graphics page) { page.drawString ("Hello World!", 50, 50); } } Hello.html <…

Read More
How can I open Java .class files in a human-readable way?

I'm trying to figure out what a Java applet's class file is doing under the hood. Opening it up with Notepad or Textpad just shows a bunch of gobbledy-gook. Is there any way to wrangle it back into a somewhat-readable …

Read More
Java Error: "Your security settings have blocked a local application from running"

I'm trying to run this simple HelloWorld code written in Java from my browser (Chrome): public class HelloWorld extends JApplet { public void init() { try { SwingUtilities.invokeAndWait(new Runnable() { public void run() { JLabel lbl = new JLabel("Hello World"); add(lbl); } }); } catch (…

Read More