Simple java applet?

linuxfreak3 · 04-28-2006, 05:55 AM

Hi all
I was wondering if someone can show me how to make a simple java applet with some buttons like submit and reset and maybe some others?

Thanks in Advance

Mega Man X · 04-28-2006, 05:58 AM

There're a few tutorials at Sun's homepage:

http://java.sun.com/applets/

Other tutorials:

http://www.dgp.toronto.edu/~mjmcguff/learn/java/

http://www.realapplets.com/tutorial/

deroB · 04-28-2006, 06:01 AM

here's a really good place to start
http://java.sun.com/docs/books/tutor...etStarted.html

or maybe get a book.
I tought myself with "Sams teach youself java in 24 days" and can highly recommend it....if it's still available

linuxfreak3 · 04-28-2006, 07:35 AM

i´ve done a little code now and need some help fixing the errors i get when i try to compile the file.
Here is the code:

Code:

import java.io.*;
import java.awt.*;
import java.awt.event.*;
public class cdapplet extends java.applet.Applet implements ActionListener
public void init ()
{
Color favvobla = new Color(51,102,153;
setBackground(favvobla);
makeTextFields();

makebuttons ();
makeTextArea ();
}
public void makeTextFields()
{
add(new Label ("Artist: "));
name = new TextField(40);
add(name);
}
public void make TextArea()
{
  display = new TextArea (50,50);
  add(display);
}
public void makeButtons()
{
laggtTillArtist = new Button ("Lägg till Cd");
laggtTillArtist.addActionListener (this);
add(laggTillArtist );
}

here is the errors:
E:\Documents and Settings\Iczer\My Documents\java\bin>javac cdapplet.java
cdapplet.java:5: illegal start of type
public void init()
^
cdapplet.java:19: '{' expected
}
^
error: interface expected here
3 errors

any ide how to fix it?

qwerty · 04-28-2006, 07:39 AM

I think you need to add a '{' after the line

Code:

public class cdapplet extends java.applet.Applet implements ActionListener

and a '}' right at the end of the class

deroB · 04-28-2006, 07:42 AM

a few typo's.

you need an "{" at the end of this line

Code:

public class cdapplet extends java.applet.Applet implements ActionListener {

and a closing bracket here:

Code:

Color favvobla = new Color(51,102,153);

also it is best to use Capitals for class names so you can easily tell them apart from from variables....
so CdApplet instead of cdapplet

and it looks like you will also need a "}" at the end of the file to close the class cdapplet

EDIT
you also need to do the following

Code:

TextField name = new TextField(40);
....and for same for 
TextArea display = new TextArea (50,50);
Button laggtTillAtrist = new Button ("Lägg till Cd");

You will also need the method "actionPerformed" to compile as you implement ActionListener.

Code:

public void actionPerformed(ActionEvent e){
    //add code here
}

jdwilder · 04-28-2006, 07:46 AM

for starters there is an open parenthesis on line 7.
Also I didn't see a constructor. YOu will need something like

public cdapplet(){
init();

}

right after the class begins "public class cdapplet extends java.applet.Applet implements ActionListener{...put it here

linuxfreak3 · 04-28-2006, 08:43 AM

Thanks for the help, but its more errors that i cant fix now.
Any suggestions?

Code:

Cdapplet.java:10: illegal start of expression
public void actionPerformed(ActionEvent e){
^
Cdapplet.java:34: ';' expected
}
 ^
Cdapplet.java:4: cdapplet should be declared abstract; it does not define action
Performed(java.awt.event.ActionEvent) in cdapplet
public class cdapplet extends java.applet.Applet implements ActionListener{
       ^
3 error

I wasnt sure what code to but between

Code:

public void actionPerformed(ActionEvent e){
    //add code here
}

So i tried the following

Code:

import java.io.*;
import java.awt.*;
import java.awt.event.*;
public class cdapplet extends java.applet.Applet implements ActionListener{
public void init ()
{

Color favvobla = new Color(51,102,153);
setBackground(favvobla);
public void actionPerformed(ActionEvent e){
    

makeTextFields();

makebuttons ();
makeTextArea ();
}
public void makeTextFields()
{
add(new Label ("Artist: "));
TextField name = new TextField(40);
add(name);
}
public void make TextArea()
{
  TextArea display = new TextArea (50,50);
  add(display);
}
public void makeButtons()
{
Button laggtTillAtrist = new Button ("Lägg till Cd");
laggtTillArtist.addActionListener (this);
add(laggTillArtist );
}
} 
}

deroB · 04-28-2006, 09:04 AM

here

this compiles but I'll let you do the testing.

good luck

Code:

import java.io.*;
import java.awt.*;
import java.awt.event.*;

public class CdApplet extends java.applet.Applet implements ActionListener{

public void init (){

    Color favvobla = new Color(51,102,153);
    setBackground(favvobla);
    makeTextFields();
    makeButtons ();
    makeTextArea ();

}

public void makeTextFields(){
    add(new Label ("Artist: "));
    TextField name = new TextField(40);
    add(name);
}

public void makeTextArea(){
    TextArea display = new TextArea (50,50);
    add(display);
}

public void makeButtons(){
    Button laggTillArtist = new Button ("Lägg till Cd");
    laggTillArtist.addActionListener (this);
    add(laggTillArtist);
}

public void actionPerformed(ActionEvent e){
    System.out.println("laggtTillArtist button pressed");
}

}//end class

Mega Man X · 04-28-2006, 09:16 AM

Ah en svensk

. Well, your code has more typos than other errors. Remember that Java is a case sensitive language. Button and button and BUTTON are three different variables. I've corrected your code and it should compile and run, but I'm sure the results will not be as pretty as you'd expect:

Code:

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class CDApplet extends JApplet implements ActionListener {
	
    public void init () {

	Color favvobla = new Color(51,102,153);
	setBackground(favvobla);
		
        makeButtons();
	makeTextArea();
	makeTextFields();
				
    }
		
    public void makeTextFields() {

	add(new Label ("Artist: "));
	TextField name = new TextField(40);
	add(name);
		
    }
		
    public void makeTextArea() {
	TextArea display = new TextArea (50,50);
	add(display);
    }
	
    public void makeButtons() {

	Button laggtTillArtist = new Button ("Lägg till Cd");

	laggtTillArtist.addActionListener (this);
	add(laggtTillArtist);
    }
	
    public void actionPerformed(ActionEvent e){
    
	makeTextFields();

	makeButtons ();
	
	makeTextArea ();
	
    }	
}

You may want to take a look in this thread where I tried to help another member with applet and listeners:

http://www.linuxquestions.org/questi...d.php?t=439390
http://www.linuxquestions.org/questi...d.php?t=439033

I'd highly recommend you to use an IDE too. It can be as simple as Dr.Java or BlueJ, up to a full-feature one as Eclipse. I recommend this because your coding style has a few problems with indentation that makes it hard to read and will eventually confuse you..

Regards!

Mega Man X · 04-28-2006, 09:18 AM

Oops... deroB is a fast typer

. Anyway, either take a look in those IDE's I've recommended or read a little about Java programming style here:

http://geosoft.no/development/javastyle.html

linuxfreak3 · 04-28-2006, 09:36 AM

Thanks for all the help

I´l try all of this after i installed knoppix.
Im getting an error when i try to install Unbuntu to, its says it can t find /dev/hdd5, i dont have hdd5 :S
any ide´s how to fix it?
i dont know how to get inside the fstab because it says no premission or something to me when i try it :S

deroB · 04-28-2006, 10:04 AM

you'll need to have root privillages to edit fstab.
type "su" at the command line to become root, then edit it.

do you know any non graphical text editors? you may have problems trying to open GUI editors as root.

linuxfreak3 · 04-28-2006, 11:38 AM

im a newbie at linux. How do i open the GUI editor ?

jdwilder · 04-28-2006, 11:51 AM

su -c 'gedit /etc/fstab'

or

su -c 'kedit /etc/fstab'

or you can replace the editor with any you chose.
if you want to be able to use the terminal while the editor is open do

$ su -

then
$ gedit /etc/fstab &

(The $ sign means the prompt the terminal is giving you, you do not need to type that yourself)