Begin Learning Java !: Item Listener

List
Checkbox
Choice
CheckboxGroup (Radio Buttons)

Public void itemStateChanged(ItemEvent)
{
------
------
}

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class FrameCheckbox extends Applet implements ItemListener
{
    Checkbox cb1, cb2, cb3;

    public void init()
{
        cb1 = new Checkbox("Java");
        cb2 = new Checkbox("VB");
        cb3 = new Checkbox("C++");

        add(cb1);
        add(cb2);
        add(cb3);

        cb1.addItemListener(this);
        cb2.addItemListener(this);
        cb3.addItemListener(this);
    }
    public void itemStateChanged(ItemEvent e)
    {
        repaint();
    }
    public void paint(Graphics g)
    {
        g.drawString("Books Selected",100,100);
        if(cb1.getState())
        {
            g.drawString("Java",100,120);
        }
        if(cb2.getState())
        {
            g.drawString("VB",100,130);
        }
        if(cb3.getState())
        {
            g.drawString("C++",100,140);
        }
    }
}

Click new -> File -> html and save this file as FrameCheckbox.html

<BODY>

<Applet code=FrameCheckbox.class height=200 width=400 >

</Applet>

</BODY>

Applet : This is to display Radio Buttons.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class FrameCheckboxGroup extends Applet implements ItemListener
{
    Checkbox cb1, cb2;
    CheckboxGroup cbg1;

    public void init()
{
        cbg1 = new CheckboxGroup();
        cb1 = new Checkbox("Male",cbg1,false);
        cb2 = new Checkbox("Female",cbg1,false);

        add(cb1);
        add(cb2);

        cb1.addItemListener(this);
        cb2.addItemListener(this);
    }
    public void itemStateChanged(ItemEvent e)
    {
        repaint();
    }
    public void paint(Graphics g)
    {
        g.drawString("Sex is : ",100,100);
        if(cb1.getState())
        {
            g.drawString("Male",150,100);
        }
        if(cb2.getState())
        {
            g.drawString("Female",150,100);
        }
    }
}

Click new -> File -> html    and save this file as FrameCheckboxGroup.html

<BODY>

<Applet code=FrameCheckboxGroup.class height=200 width=400 >

</Applet>

</BODY>

Applet : Choice (Dropdown List)

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class FrameChoice extends Applet implements ItemListener
{
    Choice c;

    public void init()
{
        c = new Choice();
        c.add("Select Option");
        c.add("Under Graduate");
        c.add("Graduate");
        c.add("Post Graduate");
        add(c);
        c.addItemListener(this);
    }
    public void itemStateChanged(ItemEvent e)
    {
        repaint();
    }
    public void paint(Graphics g)
    {
        g.drawString("Qualification : ",100,100);
        String s1 = c.getSelectedItem();
        if(s1 == "Under Graduate")
        {
            g.drawString("Under Graduate",200,100);
        }
        if(s1 == "Graduate")
        {
            g.drawString("Graduate",200,100);
        }
        if(s1 == "Post Graduate")
        {
            g.drawString("Post Graduate",200,100);
        }
    }
}

Click new -> File -> html and save this file as FrameChoice.html

<BODY>

<Applet code=FrameChoice.class height=200 width=400 >

</Applet>

</BODY>