asked on

itemListener

In my java applet, I have a list which I want to capture the selections. I am using AWT and I think I have to use itemListener to capture it.

Can anyone show me an example? say if I've got a list which looks like this

List lst = new List(4, false);
lst.add("Mercury");
lst.add("Venus");
lst.add("Earth");
lst.add("JavaSoft");
lst.add("Mars");
lst.add("Jupiter");
lst.add("Saturn");
lst.add("Uranus");
lst.add("Neptune");
lst.add("Pluto");
cnt.add(lst);

So how can I get the itemlistener to work and know what is being selected?

ia_ia_ia_1

This is an example:

package aa;

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

public class MyApplet extends Applet {

/**Construct the applet*/
public MyApplet() {
}

public void init() {
List l = new List(3);
l.addItemListener(new MyListener());
l.add("AAA");
l.add("BBB");
l.add("CCC");
add("My list", l);
}

private class MyListener implements ItemListener {
public void itemStateChanged(ItemEvent e) {
System.out.println("item: " + e.getItem());
int state = e.getStateChange();
if (state == e.SELECTED) {
System.out.println("selected...");
} else {
System.out.println("deselected..."); }
}
}
}

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ia_ia_ia_1

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YamSeng

ASKER

how I can know which value in the list is selected? ie, how to get the string of the value selected? AAA or BBB?

ia_ia_ia_1

ItemEvent.getItem returns the number of the item. Then you can get the String value by the index:

package aa;

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

public class MyApplet extends Applet {

private List l;

/**Construct the applet*/
public MyApplet() {
}

public void init() {
l = new List(3);
l.addItemListener(new MyListener());
l.add("AAA");
l.add("BBB");
l.add("CCC");
add("My list", l);
}

private class MyListener implements ItemListener {
public void itemStateChanged(ItemEvent e) {
System.out.println("item: " + e.getItem());

System.out.println(l.getItem(((Integer) e.getItem()).intValue()));

int state = e.getStateChange();
if (state == e.SELECTED) {
System.out.println("selected...");
} else {
System.out.println("deselected..."); }
}
}
}

YamSeng

ASKER

if I have the index number returned, will I be able to access the string using any of the list's method?

Or do I have to keep an array of the strings I've used in adding to the list?

ia_ia_ia_1

Yes, you can get the string value from the list - as I've shown in the last example:

l.getItem(((Integer) e.getItem()).intValue());

(Using the getItem(int index) method of the List)

ia_ia_ia_1

Do you need more help?

YamSeng

ASKER

thanks. Got it.

I misinterpreted that line...I thought it was a typo 8)

YamSeng

ASKER

thanks. Got it.

I misinterpreted that line...I thought it was a typo 8)