Dynamically adding items to a JComboBox
How about using ComboBoxModel? Something like this....
JFrame frame = new JFrame("Combo Box Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(200, 200);
frame.setLayout(new FlowLayout());
Vector comboBoxItems=new Vector();
comboBoxItems.add("A");
comboBoxItems.add("B");
comboBoxItems.add("C");
comboBoxItems.add("D");
comboBoxItems.add("E");
final DefaultComboBoxModel model = new DefaultComboBoxModel(comboBoxItems);
JComboBox comboBox = new JComboBox(model);
frame.add(comboBox);
JButton button = new JButton("Add new element in combo box");
frame.add(button);
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
model.addElement("F");
}
});
frame.setVisible(true);
Adding items dynamically to JComboBox
This looks wrong to me
int len=projects.size()-1;
String[] pro_string=new String[len];
for(int j=0;j<=len;j++)
{
pro_string[j]=projects.get(j);
}
I think it should be
int len=projects.size();
String[] pro_string=new String[len];
for(int j=0;j<len;j++)
{
pro_string[j]=projects.get(j);
}
Editing item in JCombobox dynamically
Instead of ...
getStrings().remove(position);
fireIntervalRemoved(this, position, position);
getStrings().add(position, newString);
fireIntervalAdded(this, position, position);
Which has a number of efficiency issues related to it, you could try...
getStrings().set(position, newString);
fireContentsChanged(this, position, position);
instead...
You current StringModel seems like a waste, as DefaultComboBoxModel already has a backing model of it's own. Instead, you could simple extend from AbstractListModel and implement ComboBoxModel which would give you a cleaner base class to start from, for example...
public class StringComboBoxModel extends AbstractListModel<String> implements ComboBoxModel<String> {
private List<String> values;
private String selectedItem;
public StringComboBoxModel() {
this(new ArrayList<String>(25));
}
public StringComboBoxModel(List<String> values) {
this.values = values;
}
@Override
public int getSize() {
return values.size();
}
@Override
public String getElementAt(int index) {
return values.get(index);
}
@Override
public void setSelectedItem(Object anItem) {
if (anItem instanceof String) {
selectedItem = (String) anItem;
} else {
selectedItem = null;
}
}
@Override
public Object getSelectedItem() {
return selectedItem;
}
protected List<String> getValues() {
return values;
}
}
public class MutableStringComboBoxModel extends StringComboBoxModel {
public MutableStringComboBoxModel() {
}
public MutableStringComboBoxModel(List<String> values) {
super(values);
}
public boolean contains(String value) {
return getValues().contains(value);
}
public void addValue(String value) {
getValues().add(value);
fireIntervalAdded(this, getSize() - 1, getSize() - 1);
}
public void replaceString(String oldString, String newString) {
if (contains(oldString)) {
int position = getValues().indexOf(oldString);
getValues().set(position, newString);
fireContentsChanged(this, position, position);
} else {
addValue(newString);
}
}
// Other management methods...
}
Dynamically change JComboBox
DefaultComboBoxModel<String> model = new DefaultComboBoxModel<>( yourStringArray );
comboBox.setModel( model );
Dynamically Updating JComboBox Items when another ComoboBox Changes Indexes
Change the model of the second combo box when an event happens in the first combo box. Something like:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class ComboBoxTwo extends JPanel implements ActionListener
{
private JComboBox<String> mainComboBox;
private JComboBox<String> subComboBox;
private Hashtable<String, String[]> subItems = new Hashtable<String, String[]>();
public ComboBoxTwo()
{
String[] items = { "Select Item", "Color", "Shape", "Fruit" };
mainComboBox = new JComboBox<String>( items );
mainComboBox.addActionListener( this );
// prevent action events from being fired when the up/down arrow keys are used
mainComboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
add( mainComboBox );
// Create sub combo box with multiple models
subComboBox = new JComboBox<String>();
subComboBox.setPrototypeDisplayValue("XXXXXXXXXX"); // JDK1.4
add( subComboBox );
String[] subItems1 = { "Select Color", "Red", "Blue", "Green" };
subItems.put(items[1], subItems1);
String[] subItems2 = { "Select Shape", "Circle", "Square", "Triangle" };
subItems.put(items[2], subItems2);
String[] subItems3 = { "Select Fruit", "Apple", "Orange", "Banana" };
subItems.put(items[3], subItems3);
}
public void actionPerformed(ActionEvent e)
{
String item = (String)mainComboBox.getSelectedItem();
Object o = subItems.get( item );
if (o == null)
{
subComboBox.setModel( new DefaultComboBoxModel() );
}
else
{
subComboBox.setModel( new DefaultComboBoxModel( (String[])o ) );
}
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new ComboBoxTwo() );
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
How can I dynamically change the number of items in a JComboBox
As a thought...Instead of doing all these conversions from integer to string and string to back to integer in order to fill your combo box, why not just have a combo box of Integer? You're dealing initially with integer quantity values anyways:
JComboBox<Integer> cb = new JComboBox<>();
int len = storeManager.getInv().getStockAmount(prodId);
for (int i = 1; i <= len; i++) {
cb.addItem(i);
}
cb.setSelectedIndex(0);
Your action listener might look something like this now:
okButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
Product p1 = storeManager.getInv().getProd(prodId);
int quantity = (int) cb.getSelectedItem();
/* This 'if' statement below would be moot if the Combo-Box
is properly updated unless editing is allowed in the combo
which in this case...disable that feature. */
if (quantity > storeManager.getInv().getStockAmount(prodId)) {
System.out.println("Not Enough Stock.");
} else {
storeManager.getCart().addToCart(p1, quantity);
len = storeManager.getInv().removeStockAmount(prodId, quantity);
cb.removeAllItems();
for (int i = 1; i <= len; i++) { cb.addItem(i); }
cb.setSelectedIndex(0);
}
}
});
Possibly better yet would be to utilize the JSpinner component instead of a Combo Box. A drop-down list in this use case always seems a bit obtrusive in my opinion.
Dynamic add items to JComboBox (value + icon = jlabel)
I did it & it works now just fine :) Basicaly 1. I've used a DefaultComboBoxModel, 2. I've added it to my JComboBox, 3. I've added a custom ListCellRenderer which 'translates' taken string (e.g. '#FFFFFF') to a icon & proper text and at the end creates a JLabel with that newborn icon and text.
/**
* Main Class
*/
public class ColorChooser {
...
public ColorChooser() {
...
DefaultComboBoxModel<String> model = new DefaultComboBoxModel<String>();
JComboBox combobox = new JComboBox<String>(model);
combobox.setEditable(false);
cobobox.setRenderer(new ComboRenderer());
...
}
...
}
/**
* Renderer Class
*/
public class ComboRenderer extends JLabel implements ListCellRenderer<Object> {
public ComboRenderer() {
}
public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
setFont(newFont("Consolas", Font.PLAIN, 14));
setOpaque(true);
String hex;
if (value != null) {
/*
* So basically I add to my 'model' in ColorChooser main class only Strings
* which I get e.g. from some JTextField.
* On base of this String I create icon for future JLabel
* and I set String 'value' as text for it.
*/
hex = value.toString();
Color color = HexToRgb(hex); //Method which translates String to Color
ColorSwatch icon = new ColorSwatch(10, true); // ColorSwatch is a method which creates specific square icon (in this case a little square)
icon.setColor(color);
setText(hex);
setIcon(icon);
}
return this;
}
/*
* My translate method which translates given String to a specific color value
* (RGB/RGBA)
*/
public Color HexToRgb(String colorStr) {
Color color = null;
// For String hex value '#RRGGBB'
if (colorStr.length() == 7) {
color = new Color(
Integer.valueOf(colorStr.substring(1, 3), 16),
Integer.valueOf(colorStr.substring(3, 5), 16),
Integer.valueOf(colorStr.substring(5, 7), 16));
// For String hex value '#AARRGGBB'
} else if (colorStr.length() == 9) {
color = new Color(
Integer.valueOf(colorStr.substring(3, 5), 16),
Integer.valueOf(colorStr.substring(5, 7), 16),
Integer.valueOf(colorStr.substring(7, 9), 16),
Integer.valueOf(colorStr.substring(1, 3), 16));
// For String hex value '0xRRGGBB'
} else if (colorStr.length() == 8) {
color = new Color(
Integer.valueOf(colorStr.substring(2, 4), 16),
Integer.valueOf(colorStr.substring(4, 6), 16),
Integer.valueOf(colorStr.substring(6, 8), 16));
// For String hex value '0xAARRGGBB'
} else if (colorStr.length() == 10) {
color = new Color(
Integer.valueOf(colorStr.substring(4, 6), 16),
Integer.valueOf(colorStr.substring(6, 8), 16),
Integer.valueOf(colorStr.substring(8, 10), 16),
Integer.valueOf(colorStr.substring(2, 4), 16));
} else
JOptionPane.showMessageDialog(null, "Something wen wrong... :|");
return color;
}
}
And with renderer like this I can just add items to my combobox...
try {
String hex = jtextfield.getText();
boolean canI = CheckHexValue(hex); //Method for checkin' if 'hex' String fits some specific terms
if (canI) {
combobox.insertItemAt(hex, 0);
combobox.setSelectedIndex(0);
}
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
}
...and we are home now. Hope that code will help someone :)
How To Initialize a JComboBox Whose Items are added Dynamically?
Make sure elements are added into the comboBox, using addItem().
Here's a small snippet:
import javax.swing.JComboBox;
import javax.swing.JFrame;
public class Demo {
public static void main(String[] a) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComboBox jComboBox1 = new JComboBox();
jComboBox1.addItem("Item 0");
jComboBox1.addItem("Item 1");
jComboBox1.addItem("Item 2");
jComboBox1.addItem("Item 3");
jComboBox1.addItem("Item 4");
jComboBox1.addItem("Item 5");
Object cmboitem = jComboBox1.getSelectedItem();
System.out.println(cmboitem);
frame.add(jComboBox1);
jComboBox1.setSelectedIndex(4);
frame.setSize(300, 200);
frame.setVisible(true);
}
}
EDIT
Adding from a linkedList
for(int i = 0; i < linkedList.size(); i++)
comboBox.addItem(linkedList.get(i).toString());
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