Currently working on a Swing application and I need to use a ListSelectionListener to obtain the currently selected value in a JList. I know how to add it to the JList itself, however no matter what I implement, the compiler cannot find the symbol. Any suggestions?
Source:
import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
public class ClientApp extends JFrame
{
public static void main(String[] args)
{
new ClientApp();
}
public ClientApp()
{
this.setSize(750,380);
this.setTitle("Honeydukes Muggle Ordering System");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel infoPanel = new JPanel(new CardLayout());
JPanel invntryPanel = new JPanel();
//Creating the array for the invntryPanel Jlist
String[] candy = {"Acid Pops", "Bat's Blood Soup",
"Bertie Bott's Every Flavour Beans",
"Blood-flavoured Lollipops",
"Cauldron Cakes", "Charm Choc",
"Chocoballs", "Chocolate Cauldrons",
"Chocolate Frogs", "Chocolate Skeletons",
"Chocolate Wands", "Choco-Loco", "Cockroach Clusters",
"Nougat", "Crystallised Pineapple",
"Drooble's Best Blowing Gum", "Exploding Bonbons",
"Toffees", "Fizzing Whizzbees",
"Fudge Flies", "Ice Mice",
"Jelly Slugs", "Liquourice Wands",
"Pepper Imps", "Peppermint Toads",
"Pink Coconut Ice", "Pixie Puffs",
"Pumpkin Fizz", "Salt Water Taffy",
"Shock-o-Choc", "Skeletal Sweets",
"Splindle's Lick'O'Rish Spiders",
"Sugar Quills", "Sugared Butterfly Wings",
"Toothflossing Stringmints", "Tooth-Splintering Strongmints",
"Treacle Fudge", "Chocolates", "Wizochoc"};
JList candyList = new JList(candy);
candyList.setVisibleRowCount(18);
candyList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
ListSelectionListener sl = new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting() == false) {
String currentCard = (String)candyList.getSelectedValue();
}
}
};
candyList.addListSelectionListener(sl);
//Creating a scrollpane for the JList
JScrollPane scroll = new JScrollPane(candyList, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
invntryPanel.add(scroll);
//Creating the cards
JPanel startCard = new JPanel(new BorderLayout());
JPanel acidPopsCard = new JPanel();
JPanel batsBloodSoupCard = new JPanel();
JPanel bertieBottsCard = new JPanel();
JPanel bloodPopsCard = new JPanel();
JPanel cauldronCakesCard = new JPanel();
JPanel charmChocCard = new JPanel();
JPanel chocoballsCard = new JPanel();
JPanel chocCauldronsCard = new JPanel();
JPanel chocFrogsCard = new JPanel();
JPanel chocSkeleCard = new JPanel();
JPanel chocWands = new JPanel();
JPanel chocolocoCard = new JPanel();
JPanel roachClustersCard = new JPanel();
JPanel nougatCard = new JPanel();
JPanel crystalPineappleCard = new JPanel();
JPanel droobleGumCard = new JPanel();
JPanel explodeBonbonsCard = new JPanel();
JPanel toffeesCard = new JPanel();
JPanel fizzWhizCard = new JPanel();
JPanel fudgeFliesCard = new JPanel();
JPanel iceMiceCard = new JPanel();
JPanel jellySlugsCard = new JPanel();
JPanel liquorWandsCard = new JPanel();
JPanel pepImpsCard = new JPanel();
JPanel pepToadsCard = new JPanel();
JPanel pinkCocoIceCard = new JPanel();
JPanel pixiePuffsCard = new JPanel();
JPanel pumpkFizzCard = new JPanel();
JPanel saltTaffeyCard = new JPanel();
JPanel shockChocCard = new JPanel();
JPanel skeleSweetsCard = new JPanel();
JPanel spindleSpidersCard = new JPanel();
JPanel sugarQuillsCard = new JPanel();
JPanel sugarWingsCard = new JPanel();
JPanel flossMintsCard = new JPanel();
JPanel splintMintsCard = new JPanel();
JPanel treacleFudgeCard = new JPanel();
JPanel chocolatesCard = new JPanel();
JPanel wizochocCard = new JPanel();
//Adding the cards to the infoPanel
infoPanel.add(startCard, "Start");
infoPanel.add(acidPopsCard, "Acid Pops");
infoPanel.add(batsBloodSoupCard, "Bat's Blood Soup");
infoPanel.add(bertieBottsCard, "Bertie Bott's Every Flavour Beans");
infoPanel.add(bloodPopsCard, "Blood-flavoured Lollipops");
infoPanel.add(cauldronCakesCard, "Cauldron Cakes");
infoPanel.add(charmChocCard, "Charm Choc");
infoPanel.add(chocoballsCard, "Chocoballs");
infoPanel.add(chocCauldronsCard, "Chocolate Cauldrons");
infoPanel.add(chocFrogsCard, "Chocolate Frogs");
infoPanel.add(chocSkeleCard, "Chocolate Skeletons");
infoPanel.add(chocWands, "Chocolate Wands");
infoPanel.add(chocolocoCard, "Choco-Loco");
infoPanel.add(roachClustersCard, "Cockroach Clusters");
infoPanel.add(nougatCard, "Nougat");
infoPanel.add(crystalPineappleCard, "Crystallised Pineapple");
infoPanel.add(droobleGumCard, "Drooble's Best Blowing Gum");
infoPanel.add(explodeBonbonsCard, "Exploding Bonbons");
infoPanel.add(toffeesCard, "Toffees");
infoPanel.add(fizzWhizCard, "Fizzing Whizzbees");
infoPanel.add(fudgeFliesCard, "Fudge Flies");
infoPanel.add(iceMiceCard, "Ice Mice");
infoPanel.add(jellySlugsCard, "Jelly Slugs");
infoPanel.add(liquorWandsCard, "Liquourice Wands");
infoPanel.add(pepImpsCard, "Pepper Imps");
infoPanel.add(pepToadsCard, "Peppermint Toads");
infoPanel.add(pinkCocoIceCard, "Pink Coconut Ice");
infoPanel.add(pixiePuffsCard, "Pixie Puffs");
infoPanel.add(pumpkFizzCard, "Pumpkin Fizz");
infoPanel.add(saltTaffeyCard, "Salt Water Taffy");
infoPanel.add(shockChocCard, "Shock-o-Choc");
infoPanel.add(skeleSweetsCard, "Skeletal Sweets");
infoPanel.add(spindleSpidersCard, "Splindle's Lick'O'Rish Spiders");
infoPanel.add(sugarQuillsCard, "Sugar Quills");
infoPanel.add(sugarWingsCard, "Sugared Butterfly Wings");
infoPanel.add(flossMintsCard, "Toothflossing Stringmints");
infoPanel.add(splintMintsCard, "Tooth-Splintering Strongmints");
infoPanel.add(treacleFudgeCard, "Treacle Fudge");
infoPanel.add(chocolatesCard, "Chocolates");
infoPanel.add(wizochocCard, "Wizochoc");
//startCard building
JLabel startLbl = new JLabel("<html><center>Welcome to the Honeydukes Muggle Ordering System!<br />Please select from one of our products to the left to begin!</center></html>");
startCard.add(startLbl, BorderLayout.CENTER);
this.add(invntryPanel, BorderLayout.LINE_START);
this.add(infoPanel, BorderLayout.CENTER);
this.setVisible(true);
}
}
Error:
ClientApp.java:54: error: local variable candyList is accessed from within inner
class; needs to be declared final
String currentCard = (String)candyList.getSelect
edValue();
^
Note: ClientApp.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error
ListSelectionListener is an interface and you can’t just create one by simply using a constructor. You must instantiate a concrete class only, possibly an abstract inner class for this. So do that:
Since this is homework, I’ll leave it to you to figure out what method(s) are needed, but the tutorial on using a JList and the tutorial on writing a ListSelectionListener can help you out.
Edit
Also, are you importing all the classes you need? Including the ListSelectionListener class?
i.e.,
import javax.swing.event.ListSelectionListener;