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.
Related
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.
Currently have an ArrayList called SundayList which is loaded as soon as the frame AddStudent is loaded (bit of GUI)
The code automatically generated by Netbeans is:
comboboxSunday = new javax.swing.JComboBox();
comboboxSunday.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item1", "Item2" }));
How do I load the combobox items with my own array?
The array includes items such as:
Activity1
Activity2
Activity3
Activity4
From my previous search, people mentioned about using a toString() and toArray(), and I'm not familiar with either methods, and how they help in loading the list into the combobox as I'm quite new to java..
You could create your own ComboBoxModel that takes a List as the main parameter, but that's a little more involved
comboboxSunday.setModel(new DefaultComboBoxModel());
for (Object item : listOfItems) {
comboboxSunday.addItem(item);
}
Assuming your array looks something like this:
String[] SundayList = { "Activity1", "Activity2", "Activity3", "Activity4" };
You can do this:
javax.swing.JComboBox sundayCombo = new javax.swing.JComboBox(SundayList);
If your array isn't a string array. try:
javax.swing.JComboBox sundayCombo = new javax.swing.JComboBox(SundayList.toString());
Hope this helps!
I try to fill a JList but first remove existing elements to avoid repeated records.
LLenarGrid that method call on a button to show that is to display objects in arraylist and JList but if I have 5 elements and give twice the button I get 10 doubles me as if I did not clean up the model
I leave my method, if I could help? or that I'm doing wrong, Thanks
public void LlenarGrid()
{
listapersonas.setModel(new DefaultListModel());
DefaultListModel listModel = (DefaultListModel)listapersonas.getModel();
listModel.removeAllElements();
for (clsPersona d : personas) {
listModel.addElement(d.RetornaPersona());
}
listapersonas.setModel(listModel);
listapersonas.clearSelection();
}
You do not have to set the model to list multiple times.
you can remove all element using below which you are already doing.
model.removeAllElements();
As suggested by John Bollinger check the personas List.
Is there another way to remove all items of a JComboBox then removeAllItems()? I use 2 JComboBoxes in mij app and when you select an item from the first combobox the related items should then be shown in the second combobox. When I do this, the items just keep appending after the ones that were already there. When I then first try to clear the combobox by using removeAllItems(), the second combobox is empty and stays empty whenever I change the first combobox... The first combobox keeps all its values... Does anyone see my problem?
festival is the JComboBox:
private JComboBox festival;
private JComboBox zone;
...
public void fillFestivalList(){
festival.removeAllItems();
List festivals = OP.fillFestivalList();
for(Object fest: festivals)
festival.addItem(fest.toString());
}
public void fillZoneList(String festival){
zone.removeAllItems();
List zones = OP.fillZoneList(festival);
for(Object zoneItem: zones)
zone.addItem(zoneItem.toString());
}
Regarding,
Is there another way to remove all items of a JComboBox then removeAllItems()?
Simply give the JComboBox a new model.
I would create a new DefaultComboBoxModel<T>, fill it with the newest entries, and then call setModel(...) on my JComboBox, passing in the new model when desired.
You can also Remove all the items in this way ,
but better to Give JCombobox a new DefaultComboBoxModel like the way #Hovercraft Full Of Eels said
int itemCount = combo.getItemCount();
for(int i=0;i<itemCount;i++){
combo.removeItemAt(0);
}
Currently have an ArrayList called SundayList which is loaded as soon as the frame AddStudent is loaded (bit of GUI)
The code automatically generated by Netbeans is:
comboboxSunday = new javax.swing.JComboBox();
comboboxSunday.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item1", "Item2" }));
How do I load the combobox items with my own array?
The array includes items such as:
Activity1
Activity2
Activity3
Activity4
From my previous search, people mentioned about using a toString() and toArray(), and I'm not familiar with either methods, and how they help in loading the list into the combobox as I'm quite new to java..
You could create your own ComboBoxModel that takes a List as the main parameter, but that's a little more involved
comboboxSunday.setModel(new DefaultComboBoxModel());
for (Object item : listOfItems) {
comboboxSunday.addItem(item);
}
Assuming your array looks something like this:
String[] SundayList = { "Activity1", "Activity2", "Activity3", "Activity4" };
You can do this:
javax.swing.JComboBox sundayCombo = new javax.swing.JComboBox(SundayList);
If your array isn't a string array. try:
javax.swing.JComboBox sundayCombo = new javax.swing.JComboBox(SundayList.toString());
Hope this helps!