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JList setSelectedValue not working

I have a JList in Swing working bad. I list all items from Database into the list with no problem with this code.
My code:
Integer index = null;
DefaultListModel<String> model = new DefaultListModel<String>();
index = DataBase.getIndex1(cbActivity.getSelectedItem().toString());
activities = DataBase.getIndex2(index);
for(MapActivity mapActitivy : activities)
{
model.addElement(mapActivity.getActivity().toString());
}
jList.setModel(model);
But now, I would like to select individual or multiple selection, but nothing I tried works. I tried:
jList.setSelectedValue("Ball", true);
//jList.setSelectedIndex(2);
jList.setSelectionBackground(Color.red);
But nothing happen. Just the list on screen with nothing selected. Single or multiple.
Any help?

Try this:
setSelectedIndex(1); // here use index of items
or if it does not work use below one:
setSelectedItem("ball") // here use name of item.

Populating JComboBox using an MultiDimensional Array List

I have been trying to populate a Eclipse GUI Java JComboBox using an Array list using constructors without any luck. This is what I have tried thus far.
import item.Item;
import javax.swing.JComboBox;
import java.util.ArrayList;
public class SelectionScreen{
private JFrame frame;
static ArrayList< Item> list;
private String items;
public static void main (String[] args){
initialize();
}
public void initialize(){
list = new ArrayList< Item >();
list.add(new Item("Strawberry,200,.25,.75);
list.add(new Item("Banana,200,.25,1.00);
list.add(new Item("Oranges,200,.25,2.00);
JcomboBox comboBox = newJcomboBox();
ComboBox.setBounds(63,29,86,22)
frame.getContentPane().add(comboBox);
// here is where I tried to fill the combobox
//comboBox.setModel(new DefaultComboBoxModel(Item.getName()))); //Wrong
//comboBox.setModel(Item.getName); //Wrong
//the following only loads the last item in the list which is Oranges
for(Item i: list{
comboBox.setModel(new DefaultComboBoxModel(New String[] {
i.getName()}));
}
// tried making a different list to collect my fruits.
for(Item i: list){
list2[ i.getName()];
Item.length;
} //which was a complete fail.
I am at complete lost here and not very experienced with Java. I can load the items just fine using
comboBox.setModel(new DefaultComboBoxModel(new String[]{ "Strawberry","Banana","Oranges"}));
but I won't know what fruits are in the list when I import them from a text file.
Any help would be appreciated.

/*The following only loads the last item in the list which is Oranges.*/
for(Item i: list)
{
comboBox.setModel(new DefaultComboBoxModel(new String[] {
i.getName()}));
}
Don't keep creating a new ComboBoxModel inside the loop. You can't add more than one item to the model if you keep creating a new model. So you only see the last model created with the single item added to it. If you want to use this approach then you would create the model OUTSIDE of the loop and then just add items the model INSIDE the loop.
Actually you don't event need to create a combo box model. You can just add items directly to the combo box:
Something like:
for(Item i: list
{
comboBox.addItem( i.getName() );
}
Another option is to add the Item object directly to the combo box. Then you can use a custom renderer to control which property of the Item object is display in the combo box. Check out Combo Box With Custom Renderer for more information on this approach.

If you wish to show Item objects in a combobox then you should declare the JComboBox to store Item objects. That way you can easily add items without having to do any mucking around with models at all:
JComboBox<Item> itemsCombo = new JComboBox<>();
list.forEach(itemsCombo::add);
The value displayed in the combobox will be whatever is returned by Item.toString. If that's not what you want (because your toString returns a more complete description of the object - generally considered better practice) then it is fairly easy to write your own Custom Renderer.
The only hackish downside of the JComboBox API is that you've got to cast the selected item:
Item selectedItem = (Item)itemsCombo.getSelectedItem();
This is ugly and I wish the API didn't require it but it's a small price to pay to avoid having to define your own model.
You can, in fact, avoid the cast by:
Item selectedItem = itemsCombo.getItemAt(itemsCombo.getSelectedIndex());
But that's just about as ugly.
As an aside, this is one of several areas in which the standard Java tutorial and samples are quite out of date so there's no blame here at all for not knowing to use generics.

Fetch array of strings from ArrayList for JList Java

the task which I do is quite simple, but I faced one problem with JList component.
What i need is. I fetch data from DataBase, load it to String array, pack array into ArrayList (just because I duno how many records I have), return it from method as ArrayList.
Now at receiver side. I have a trouble, I cant fetch String array from ArrayList so that I can pass to JList.
Here is the code.
ArrayList<Object> fetch = new ArrayList<Object>();
public String[] data =new String[10];
listModel = new DefaultListModel();
myList = new JList(listModel);
//myList = new JList(data);
// So it works with simple array of strings.
fetch=DAO.loadPasswords();
//At this point it asks me to cast an object to smth which late cause null pointer exception.
myList = new JList(fetch.get(0));
And here is loadPasswords();
public static ArrayList<Object> loadPasswords(){
dbConnect();
boolean unswer = false;
String[] result=null;
String query1 = "select * from tblPasswordsStorage where "
+ "_user_id = ?";
String userId=Personal_Organizer.userProfile.getUserID();
ArrayList<Object> params = new ArrayList<Object>();
params.add(userId);
executeQueryP(query1, params);
ArrayList<Object> fetched=null;
try {
if (rs.next()) {
unswer = true;
//Personal_Organizer.userProfile.setUserID(rs.getString(1));
result[0]=rs.getString(1);
result[1]=rs.getString(2);
result[2]=rs.getString(3);
result[3]=rs.getString(4);
result[4]=rs.getString(5);
result[5]=rs.getString(6);
result[6]=rs.getString(7);
result[7]=rs.getString(8);
result[8]=rs.getString(9);
result[9]=rs.getString(10);
fetched.add(result);
}
if (unswer) {
while (rs.next()) {
Tools.print(rs.getString(1));
}
}
} catch (SQLException ex) {
JOptionPane.showMessageDialog(null,
"SQL Server connection issue.\n"
+ "Please, check Server address, user name and password.",
"Output",
JOptionPane.PLAIN_MESSAGE);
}
dbClose();
return fetched;
}
I tried to use multidimensional array but still JList require single dimensional array.

Either use a DefaultListModel and load it with your Strings using a simple for or for-each loop that loops through your ArrayList, adding each String item in the ArrayList into the model, or create your own ListModel class, one that extends AbstractListModel and that uses the ArrayList as its data nucleus.
Edit, since your data is held in an ArrayList of arrays, then perhaps you don't want to display it within an ArrayList after all, but rather in a JTable. Here your best bet would be to create your own TableModel, one based off of AbstractTableModel and that uses your ArrayList as its data nucleus. Also, perhaps better than loading your data into an array would be to create a custom class to hold each row of data from the ResultSet.
You state:
My problem is to simply load something to JList. The idea is to display application/website name in the list, then when you click on it, you get full data which contains in array. That's why I put fetch.get(0)...because. I need at least something.
Then
Create a custom class to hold each row of data.
Create items of this class from each row of the ResultSet
Fill your DefaultListModel with items of this class
Give your JList a custom ListCellRenderer, one that display's the application/website name
Then you can display the name and still have each list item hold all the pertinent information that it needs.

How this API can get items of a JList (String)

I have a JList with a few items, Then I got an API that need to get the selected item and use it to provide some information about that item. My problem is that the type of the JList is String and the type of my API is obviously something different. Lets say LocationAPI. So the API gets index only from its own type and not other ones. I am looking for a solution to convert the selected item (String) to something suitable for the API. Here is a simple example of the API.
LinkedList<LocationAPI> stations = FetchWeatherForecast.findWeatherStationsNearTo("cityName");
for (LocationAPI station : stations) { System.out.println(station); }
// Assume the first match on the list is correct
LocationAPI firstMatch = stations.getFirst();
List<ForecastForOneDay> forecast = FetchWeatherForecast.getWeatherForecast(firstMatch);
So it is a simple example of how the API works, But Instead of 'firstMatch' and 'Station' I have to use my own items and lists. I got the Item and list, but I made them differently:
DefaultListModel<String> cityPlace = new DefaultListModel<String>();
JList myList = new JList(cityPlace);
So how can I use the items of the above list in the API??

add arraylist data to JTable

i hav a ArreayList which is contain PRIvariable(name of the class) class data. Below shows my part of the java code. So now i want to put this Arraylist data to Jtable. how can i do that. Here i already added pri.dateText , pri.sum , pri.count to ar(arraylist)
PRIvariable pri=new PRIvariable();
while (reader.ready()) {
String line = reader.readLine();
String[] values = line.split(",");
if(values[2].equals(pri.incDate)){
if(values[4].equals("KI")){
pri.dateText=values[2]+" "+values[4];
pri.count=pri.count+1;
pri.sum = pri.sum+Integer.parseInt(values[7]);
}
}
}
System.out.println(pri.dateText+" "+pri.sum+" "+pri.count);
ar.add(pri);

Like all Swing components, a JTable relies upon the MVC pattern (at multiple levels, but that's not the subject).
You have one view (the JTable), one model (I'll come back on it later), and a controller (implemented here as a set of event listeners : one controller for each kind of control).
The array you have could be a good model starting point. However, Swing provides far better way to inject your data in JTable. Indeed, a JTable uses as model an implementation of TableModel. Hopefully, there already exist an implementation : DefaultTableModel.
So, here is what I suggest to you : create DefaultTableModel, put in its rows/columns all the data you want to display in your table, then call JTable#setModel(TableModel) to have thze table display your data.
Obviously, you'll soon find various misfits between DefaultTableModel and what you want to do. It will then be time for you to create our very own table model. But that's another question.
Besides, don't forget to take a look at Swing tutorial, it's usually a good thing when dealing with Swing components.

I don't see where you have an ArrayList anywhere.
First you create a PRIvariable object. Then you keep looping as you read a line of data from the file. For each line of data you split it into individual tokens and then add some of the token data to the PRIvariable ojbect. The problem is that you only have a single PRIVariable object. So every time you read a new line of data you change the values of the PRIvariable object. After all the looping you add this single PRIvariable object to your ArrayList, but you will only ever have one object in the ArrayList.
The easier solution is to update the TableModel as you get the data. Something like:
DefaultTableModel model = new DefaultTableModel(...);
JTable table = new JTable( model );
...
...
while (reader.ready())
{
String line = reader.readLine();
String[] values = line.split(",");
String[] row = new String[3];
row[0] = values[?];
row[1] = values[?];
row[2] = values[?];
model.addRow( row );
}

Look into GlazedLists. They make it extremely easy to create a suitable TableModel object from your list.
ArrayList< PRIvariable> myList = new ArrayList<PRIvariable>();
... fill up the list ...
// This assumes your object has a getName() and getAge() methods
String[] propertyNames = {"name","age"};
String[] columnLabels = {"Name","Age"};
// Are these columns editable?
boolean[] writeable = {false, false};
EventList<PRIvariable> eventList = GlazedLists.eventList(myList);
EventTableModel<PRIvariable> tableModel = new EventTableModel<PRIvariable>(eventList,propertyNames,columnLabels,writable);
JTable table = new JTable(tableModel);