Search within a JList

[Mikey]

For my assignment, I was asked if I could implement a search textbox so that when someone types say a name in the textbox, it highlights the name in the JList or at least tells you that it exists. I may have to implement a search button as well. I'm not sure how to go about doing this, however I have found a method called getNextMatch which supposedly allows you to search within a JList but I have no idea how to apply it. If anyone has any ideas or any suggestions it would be really helpful.

[DarrylBurke]

Here's a few hints:

What type of value is returned from JList#getNextMatch?

What is the significance of the returned value?

Do you see a JList method that selects a single cell?

db

[Mikey]

The value returned is an Int. The definition from Oracle is 'Returns the data model that holds the list of items displayed by the JList component'. I hope this will do what I want it to do.
The significance of the returned value is one of the data items in the JList I am assuming.
I have this: list.setSelectionMode(ListSelectionModel.SINGLE_SE LECTION);
I'm not sure on a particular method exactly though. Btw, I am not a very experienced programmer and I don't find it very easy! However I don't give up easy either.

[Mikey]

I've thought of another way of doing it. Is it possible to compare an item in a list to a typed string using the compareTo method? If thats possible then it could work this way.

[DarrylBurke]

Read through all the methods. Do you see a method that sets the selected index?

db

[Mikey]

Yes I do see a method called setSelectedIndex(). Right thats half working! Got the setSelectedIndex at 0 and when I type a search and press the search button its going straight to the first index. I want it to match the String value. However its a really helpful start! Thanks. What would you suggest to use to match the typed string to the correct index? Many thanks for all our help!

[DarrylBurke]

What would you suggest to use to match the typed string to the correct index?

You already have a good approach for that in your first post.

db

[Mikey]

Right well its just figuring out how to apply getNextMatch() to list.setSelectedIndex() . At the moment i've got:
String s = search.getText(); //search = JTextfield with a JButton attached
if (s.length() >=0) {

list.getNextMatch(s, 0, Bias.Forward);
list.setSelectedIndex(0);

}
}

[DarrylBurke]

getNextMatch(...) returns a value. I don't see you using that returned value.

db

edit You're very close to attaining a solution. That ---><--- close ;)

[Mikey]

Right thats good news! It says that it Returns the index of the next list element that starts with the prefix. Which is exactly what I want. So I need something like:
list.getNextMatch(s, 0, Bias.Forward);
return list. i'm suck after here! (I know its the index of 's' which is the prefix)...

[DarrylBurke]

Think about this. You already have this line of code

if (s.length() >=0) {

The length() method of class String is also a method that returns int. In that line of code, you are comparing the returned value to 0. You probably already have other lines of code that invoke a method and use the value returned in some way.

If you put s.length(); on a line all by itself, the method is called but the returned value is discarded. And that's what you're doing with getNextMatch(...).

Assign the returned value to a variable and use that variable to set the selection and you're good to go.

db

[Mikey]

Right, I understand what you are saying, however I am still unfortunately confused. I am doing the right thing with the 'if' statement? And I know I am not returning a value with getNextMatch but I am unsure how to do this. Also is the returned value 's'? and you apply the returned value to a variable to set, setSelectedIndex();. I am also unsure how to assign a returned value to a variable. I am awfully frustrated with myself as I should be able to do this!!

[DarrylBurke]

setSelectedIndex(getNextMatch(...))

db

[Mikey]

Thanks for that, however its complaining saying that it 'cannot find symbol'. It doesn't know what this method is.

[Tolls]

Show your code, because Darryl's example is more pseudo-code than cut-n-paste code.

[Mikey]

ok, this is what i've got:
Searchbtn.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

String s = search.getText();
if (s.length() <=0) {
JOptionPane.showMessageDialog(Searchbtn,"No search query entered! ", "No query",
JOptionPane.WARNING_MESSAGE);
}

if (s.length() >=0) {

list.setSelectedIndex(getNextMatch (s, 0, Bias.Forward));



}
}

[Tolls]

getNextMatch is a method on your JList...

[Mikey]

Yes, it is. Thats what I need to use to return a value to search for an item using a string in the JList. Darryl was a great help in providing me with some points to help with this.

[Tolls]

So, is it sorted then?

[Mikey]

Unfortunatly not, i'm still confused how to use and where to put certain methods that Darryl has said for me to use.