我正在尝试使用CardLayout制作主面板（即其他所有面板上的面板）显示不同的面板（默认情况下是用户可以浏览产品的面板），以便用户可以查看他们的购物车和结帐。我相信我应该有ButtonListener和所有设置，但CardLayout.show方法仍然没有做它的事情。有什么我想念的吗？
感谢您的帮助。
来源：
import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.*;
import java.text.NumberFormat;
public class ClientApp extends JFrame
{
public static void main(String[] args)
{
new ClientApp();
}
private JButton switchCard;
private JPanel infoPanel;
private JPanel mainPanel;
private JPanel cartPanel;
private JPanel orderingPanel;
private JList candyList;
private CardLayout cl = new CardLayout();
private JPanel checkoutPanel;
private JButton checkoutButton;
private JTextField acidPopsTF;
private JTextField bertieBottsTF;
private JTextField bloodPopsTF;
private JTextField cauldronCakesTF;
private JTextField charmChocTF;
private JTextField chocoballsTF;
private JTextField chocCauldronsTF;
private JTextField chocFrogsTF;
private JTextField chocWandsTF;
private JTextField roachClustersTF;
private JTextField crystalPineappleTF;
private JTextField droobleGumTF;
private JTextField explodeBonbonsTF;
private JTextField fizzWhizTF;
private JTextField iceMiceTF;
private JTextField jellySlugsTF;
private JTextField liquorWandsTF;
private JTextField pepImpsTF;
private JTextField pinkCocoIceTF;
private JTextField spindleSpidersTF;
private JTextField sugarQuillsTF;
private JTextField wizochocTF;
private JTextField shockChocTF;
private ArrayList cart;
private Object[] cartArray;
public ClientApp()
{
this.setSize(750,400);
this.setTitle("Honeydukes Muggle Ordering System");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ButtonListener bl = new ButtonListener();
mainPanel = new JPanel(cl);
cartPanel = new JPanel();
orderingPanel = new JPanel(new BorderLayout());
infoPanel = new JPanel(cl);
JPanel invntryPanel = new JPanel(new BorderLayout());
checkoutPanel = new JPanel(new BorderLayout());
//Creating the array for the invntryPanel Jlist
String[] candy = {"Acid Pops", "Bertie Bott's Every Flavour Beans",
"Blood-flavoured Lollipops",
"Cauldron Cakes", "Charm Choc",
"Chocoballs", "Chocolate Cauldrons",
"Chocolate Frogs","Chocolate Wands",
"Cockroach Clusters", "Crystallised Pineapple",
"Drooble's Best Blowing Gum", "Exploding Bonbons",
"Fizzing Whizbees", "Ice Mice",
"Jelly Slugs", "Liquourice Wands",
"Pepper Imps", "Pink Coconut Ice",
"Shock-o-Choc", "Splindle's Lick'O'Rish Spiders",
"Sugar Quills", "Wizochoc"};
candyList = new JList(candy);
candyList.setVisibleRowCount(18);
candyList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
//Creating a scrollpane for the JList
JScrollPane scroll = new JScrollPane(candyList, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
invntryPanel.add(scroll);
switchCard = new JButton("View Product");
switchCard.addActionListener(bl);
invntryPanel.add(switchCard, BorderLayout.PAGE_END);
//Creating the cards
JPanel startCard = new JPanel(new BorderLayout());
JPanel acidPopsCard = new JPanel(new BorderLayout());
JPanel bertieBottsCard = new JPanel(new BorderLayout());
JPanel bloodPopsCard = new JPanel(new BorderLayout());
JPanel cauldronCakesCard = new JPanel(new BorderLayout());
JPanel charmChocCard = new JPanel(new BorderLayout());
JPanel chocoballsCard = new JPanel(new BorderLayout());
JPanel chocCauldronsCard = new JPanel(new BorderLayout());
JPanel chocFrogsCard = new JPanel(new BorderLayout());
JPanel chocWandsCard = new JPanel(new BorderLayout());
JPanel roachClustersCard = new JPanel(new BorderLayout());
JPanel crystalPineappleCard = new JPanel(new BorderLayout());
JPanel droobleGumCard = new JPanel(new BorderLayout());
JPanel explodeBonbonsCard = new JPanel(new BorderLayout());
JPanel fizzWhizCard = new JPanel(new BorderLayout());
JPanel iceMiceCard = new JPanel(new BorderLayout());
JPanel jellySlugsCard = new JPanel(new BorderLayout());
JPanel liquorWandsCard = new JPanel(new BorderLayout());
JPanel pepImpsCard = new JPanel(new BorderLayout());
JPanel pinkCocoIceCard = new JPanel(new BorderLayout());
JPanel shockChocCard = new JPanel(new BorderLayout());
JPanel spindleSpidersCard = new JPanel(new BorderLayout());
JPanel sugarQuillsCard = new JPanel(new BorderLayout());
JPanel wizochocCard = new JPanel(new BorderLayout());
//Adding the cards to the infoPanel
infoPanel.add(startCard, "Start");
infoPanel.add(acidPopsCard, "Acid Pops");
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(chocWandsCard, "Chocolate Wands");
infoPanel.add(roachClustersCard, "Cockroach Clusters");
infoPanel.add(crystalPineappleCard, "Crystallised Pineapple");
infoPanel.add(droobleGumCard, "Drooble's Best Blowing Gum");
infoPanel.add(explodeBonbonsCard, "Exploding Bonbons");
infoPanel.add(fizzWhizCard, "Fizzing Whizbees");
infoPanel.add(iceMiceCard, "Ice Mice");
infoPanel.add(jellySlugsCard, "Jelly Slugs");
infoPanel.add(liquorWandsCard, "Liquourice Wands");
infoPanel.add(pepImpsCard, "Pepper Imps");
infoPanel.add(pinkCocoIceCard, "Pink Coconut Ice");
infoPanel.add(shockChocCard, "Shock-o-Choc");
infoPanel.add(spindleSpidersCard, "Splindle's Lick'O'Rish Spiders");
infoPanel.add(sugarQuillsCard, "Sugar Quills");
infoPanel.add(wizochocCard, "Wizochoc");
//building the cards
startBuilder("honeydukes.jpg", "<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);
verticalBuilder("acidPops.jpg", "<html><center>One of our more exotic treats, Acid Pops are sure to pack a punch!<br /><small>Disclaimer: Honeydukes is not responsible for any injury resulting from use of our products.</small><br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$5.95</center></html>", acidPopsTF, acidPopsCard);
verticalBuilder("BertieBotts.jpg", "<html><center>A classic wizard candy, Bertie Bott's are known for having a danger in every mouthful. Is that light brown one toffee, or is it earwax? Only one way to find out!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$16.95</center></html>", bertieBottsTF, bertieBottsCard);
verticalBuilder("bloodpop.jpg", "<html><center>For those of more unusual tastes, we have this most interesting lollipop. We won't ask any questions, and anonymity is guaranteed.<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$5.95</center></html>", bloodPopsTF, bloodPopsCard);
verticalBuilder("cauldroncake.jpg", "<html><center>A wizarding favourite, cauldron cakes are chocolate on the outside, and pure heaven on the inside. No desert is complete without one!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$14.95</center></html>", cauldronCakesTF, cauldronCakesCard);
verticalBuilder("charmchoc.jpg", "<html><center>A candy staple, not only is Charm Choc made of the finest chocolate, it's also charmed for extra flavour!<br /><br />$5.95</center></html>", charmChocTF, charmChocCard);
horizontalBuilder("chocoballs.jpg", "<html><center>One of our most popular candies, Chocoballs are chocolate on the outside, but the inside is full of delicious strawberry mousse and clotted cream!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", chocoballsTF, chocoballsCard);
verticalBuilder("choccauldrons.jpg", "<html><center>A wizarding favourite, each and every Chocolate Cauldron are filled to the brim with our own special brew of Firewhiskey!<br /><br />NOTICE: The Ministry of Magic would like to remind all that Firewhisky is an alcoholic beverage, and is not to be consumed by those who are underaged.<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$14.95</center></html>", chocCauldronsTF, chocCauldronsCard);
verticalBuilder("chocfrogs.jpg", "<html><center>One of the most famous wizarding sweets, Chocolate Frogs are made of the finest Croakoa, enabling them to behave like actual frogs! Each Chocolate Frog comes with card featuring a famous witch or wizard! Try to collect them all!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$14.95</center></html>", chocFrogsTF, chocFrogsCard);
horizontalBuilder("chocwands.jpg", "<html><center>Popular as both a gag gift and a tasty treat, chocolate wands are one candy that nobody leaves the shop without!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", chocWandsTF, chocWandsCard);
verticalBuilder("cockroachclusters.jpg", "<html><center>Great for tricking friends or quenching your insatiable hunger for cockroaches, these peculiar treats will never get old!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$5.95</center></html>", roachClustersTF, roachClustersCard);
verticalBuilder("crystalpineapple.jpg", "<html><center>Endorsed by Professor Horace Slughorn himself, Crystallised pineapple consists of the best pineapples diced up, and then cooked in sugar syrup. This is one sweet treat you don't want to be without!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", crystalPineappleTF, crystalPineappleCard);
verticalBuilder("gum.jpg", "<html><center>Guaranteed to never lose its flavour, Drooble's Best Blowing Gum will let you blow bubbles that last for days, and is the best wizarding gum out there!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$2.95</center></html>", droobleGumTF, droobleGumCard);
verticalBuilder("bonbons.jpg", "<html><center>Produced by Kaboon Choco Ltd., these treats pop in your mouth -- literally!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", explodeBonbonsTF, explodeBonbonsCard);
verticalBuilder("whizbees.jpg", "<html><center>Made from delicious sherbert, Fizzing Whizbees have the effect of also causing you to float a few inches off the ground while sucking on them!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", fizzWhizTF, fizzWhizCard);
verticalBuilder("mice.jpg", "<html><center>Charmed to stay cold up to the point of being enjoyed, ice mice will also cause your teeeth to chatter and squeak!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$5.95</center></html>", iceMiceTF, iceMiceCard);
verticalBuilder("slugs.jpg", "Perhaps the single most popular sweet, Jelly Slugs are a classic!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$2.95</center></html>", jellySlugsTF, jellySlugsCard);
verticalBuilder("liqwand.jpg", "<html><center>Another favourite, these wands won't win you any duels, but they sure are tasty!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$9.95</center></html>", liquorWandsTF, liquorWandsCard);
verticalBuilder("imps.jpg", "<html><center>Famous for making anyone who eats them smoke at the ears and nose, these spicy treats are delicious!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$4.95</center></html>", pepImpsTF, pepImpsCard);
verticalBuilder("pinkice.jpg", "<html><center>Amazing in every way, these shimmering pink squares are even more enjoyable than they look!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$4.95</center></html>", pinkCocoIceTF, pinkCocoIceCard);
verticalBuilder("shock.jpg", "<html><center>Add some SHOCK to your Choc-o-late! Perfect for practical jokes, and tasty too!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$4.95</center></html>", shockChocTF, shockChocCard);
verticalBuilder("spiders.jpg", "<html><center>Made entirely out of liquorice, these treats are even bewitched to seem alive!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$4.95</center></html>", spindleSpidersTF, spindleSpidersCard);
verticalBuilder("quill.jpg", "<html><center>Perfect for nibbling on during lectures, the professor will never know the difference between you thinking and you enjoying a delicious sugar quill!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$1.95</center></html>", sugarQuillsTF, sugarQuillsCard);
verticalBuilder("wizochoc.jpg", "<html><center>There's been an age old debate between wizards of all ages as to whether CharmChoc or WizoChoc is better. Now Muggles can join in as well!<br /><br /><br />Type the quantity of this product you would like to order below.<br /><br />$5.95</center></html>", wizochocTF, wizochocCard);
checkoutButton = new JButton("Checkout");
checkoutButton.addActionListener(bl);
checkoutPanel.add(checkoutButton, BorderLayout.LINE_END);
orderingPanel.add(checkoutPanel, BorderLayout.PAGE_END);
orderingPanel.add(invntryPanel, BorderLayout.LINE_START);
orderingPanel.add(infoPanel, BorderLayout.CENTER);
mainPanel.add(orderingPanel, "Ordering");
mainPanel.add(cartPanel, "Cart");
this.add(mainPanel);
this.setVisible(true);
}
void startBuilder(String p, String l, JPanel n)
{
try {
BufferedImage myPicture = ImageIO.read(new File(p));
JLabel picLabel = new JLabel(new ImageIcon(myPicture));
n.add(picLabel, BorderLayout.LINE_END);
}
catch (IOException e) {}
JLabel lbl = new JLabel(l);
n.add(lbl, BorderLayout.CENTER);
}
void verticalBuilder(String p, String l, JTextField t, JPanel n)
{
try {
BufferedImage myPicture = ImageIO.read(new File(p));
JLabel picLabel = new JLabel(new ImageIcon(myPicture));
n.add(picLabel, BorderLayout.LINE_END);
}
catch (IOException e) {}
JLabel lbl = new JLabel(l);
n.add(lbl, BorderLayout.CENTER);
t = new JTextField();
n.add(t, BorderLayout.PAGE_END);
}
void horizontalBuilder(String p, String l, JTextField t, JPanel n)
{
try {
BufferedImage myPicture = ImageIO.read(new File(p));
JLabel picLabel = new JLabel(new ImageIcon(myPicture));
n.add(picLabel, BorderLayout.PAGE_START);
}
catch (IOException e) {}
JLabel Lbl = new JLabel(l);
n.add(Lbl, BorderLayout.CENTER);
t = new JTextField();
n.add(t, BorderLayout.PAGE_END);
}
private class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == switchCard)
{
cl.show(infoPanel, (String)candyList.getSelectedValue());
}
if (e.getSource() == checkoutButton)
{
NumberFormat cf = NumberFormat.getCurrencyInstance();
String acidPopsCost = cf.format(Total(1, 5.95, acidPopsTF));
String bertieBottsCost = cf.format(Total(1, 16.95, bertieBottsTF));
String bloodPopsCost = cf.format(Total(1, 5.95, bloodPopsTF));
String cauldronCakesCost = cf.format(Total(1, 14.95, cauldronCakesTF));
String charmChocCost = cf.format(Total(1, 5.95, charmChocTF));
String chocoballsCost = cf.format(Total(1, 9.95, chocoballsTF));
String chocCauldronsCost = cf.format(Total(1, 14.95, chocCauldronsTF));
String chocFrogsCost = cf.format(Total(1, 14.95, chocFrogsTF));
String chocWandsCost = cf.format(Total(1, 9.95, chocWandsTF));
String roachClustersCost = cf.format(Total(1, 5.95, roachClustersTF));
String crystalPineappleCost = cf.format(Total(1, 9.95, crystalPineappleTF));
String droobleGumCost = cf.format(Total(1, 2.95, droobleGumTF));
String explodeBonbonsCost = cf.format(Total(1, 9.95, explodeBonbonsTF));
String fizzWhizCost = cf.format(Total(1, 9.95, fizzWhizTF));
String iceMiceCost = cf.format(Total(1, 5.95, iceMiceTF));
String jellySlugsCost = cf.format(Total(1, 2.95, jellySlugsTF));
String liquorWandsCost = cf.format(Total(1, 9.95, liquorWandsTF));
String pepImpsCost = cf.format(Total(1, 4.95, pepImpsTF));
String pinkCocoIceCost = cf.format(Total(1, 4.95, pinkCocoIceTF));
String shockChocCost = cf.format(Total(1, 4.95, shockChocTF));
String spindleSpidersCost = cf.format(Total(1, 4.95, spindleSpidersTF));
String sugarQuillsCost = cf.format(Total(1, 1.95, sugarQuillsTF));
String wizochocCost = cf.format(Total(1, 5.95, wizochocTF));
int acidPopsNum = (int)Total(0, 0, acidPopsTF);
int bertieBottsNum = (int)Total(0, 0, bertieBottsTF);
int bloodPopsNum = (int)Total(0, 0, bloodPopsTF);
int cauldronCakesNum = (int)Total(0, 0, cauldronCakesTF);
int charmChocNum = (int)Total(0, 0, charmChocTF);
int chocoballsNum = (int)Total(0, 0, chocoballsTF);
int chocCauldronsNum = (int)Total(0, 0, chocCauldronsTF);
int chocFrogsNum = (int)Total(0, 0, chocFrogsTF);
int chocWandsNum = (int)Total(0, 0, chocWandsTF);
int roachClustersNum = (int)Total(0, 0, roachClustersTF);
int crystalPineappleNum = (int)Total(0, 0, crystalPineappleTF);
int droobleGumNum = (int)Total(0, 0, droobleGumTF);
int explodeBonbonsNum = (int)Total(0, 0, explodeBonbonsTF);
int fizzWhizNum = (int)Total(0, 0, fizzWhizTF);
int iceMiceNum = (int)Total(0, 0, iceMiceTF);
int jellySlugsNum = (int)Total(0, 0, jellySlugsTF);
int liquorWandsNum = (int)Total(0, 0, liquorWandsTF);
int pepImpsNum = (int)Total(0, 0, pepImpsTF);
int pinkCocoIceNum = (int)Total(0, 0, pinkCocoIceTF);
int shockChocNum = (int)Total(0, 0, shockChocTF);
int spindleSpidersNum = (int)Total(0, 0, spindleSpidersTF);
int sugarQuillsNum = (int)Total(0, 0, sugarQuillsTF);
int wizochocNum = (int)Total(0, 0, wizochocTF);
cart = new ArrayList();
addCart("Acid Pops", acidPopsNum, acidPopsCost);
addCart("Bertie Botts Every Flavour Beans", bertieBottsNum, bertieBottsCost);
addCart("Blood-flavoured Lollipops", bloodPopsNum, bloodPopsCost);
addCart("Cauldron Cakes", cauldronCakesNum, cauldronCakesCost);
addCart("Charm Choc", charmChocNum, charmChocCost);
addCart("Chocoballs", chocoballsNum, chocoballsCost);
addCart("Chocolate Cauldrons", chocCauldronsNum, chocCauldronsCost);
addCart("Chocolate Frogs", chocFrogsNum, chocFrogsCost);
addCart("Chocolate Wands", chocWandsNum, chocWandsCost);
addCart("Cockroach Clusters", roachClustersNum, roachClustersCost);
addCart("Crystallised Pineapple", crystalPineappleNum, cauldronCakesCost);
addCart("Drooble's Best Blowing Gum", droobleGumNum, droobleGumCost);
addCart("Exploding Bonbons", explodeBonbonsNum, explodeBonbonsCost);
addCart("Fizzing Whizbees", fizzWhizNum, fizzWhizCost);
addCart("Ice Mice", iceMiceNum, iceMiceCost);
addCart("Jelly Slugs", jellySlugsNum, jellySlugsCost);
addCart("Liquorice Wands", liquorWandsNum, liquorWandsCost);
addCart("Pepper Imps", pepImpsNum, pepImpsCost);
addCart("Pink Coconut Ice", pinkCocoIceNum, pinkCocoIceCost);
addCart("Shock-o-Choc", shockChocNum, shockChocCost);
addCart("Splindle's Lick'O'Rish Spiders", spindleSpidersNum, spindleSpidersCost);
addCart("Sugar Quills", sugarQuillsNum, sugarQuillsCost);
addCart("Wizochoc", wizochocNum, wizochocCost);
cart.remove(cart.size());
cartArray = cart.toArray();
cl.show(mainPanel, "Cart");
}
}
double Total(int i, double p, JTextField t)
{
if (i == 1)
{
try
{
return (p* (Integer.parseInt(t.getText())));
}
catch (NumberFormatException e) { return 0; }
}
else
{
try
{
return Integer.parseInt(t.getText());
}
catch (NumberFormatException e) { return 0; }
}
}
void addCart(String p, int n, String c)
{
if (n > 0)
{
cart.add(p);
cart.add(n);
cart.add(c);
cart.add("");
}
}
}
}
答案 0 :(得分：0)
Dude，您的代码中有许多更正要实施。这是清单 -
在方法verticalBuilder / horizontalBuilder中，您要传递要添加到相应面板的对象。但这些方法实际上是为JTextField..see行＃228创建新对象（t）。因此，当第一次从第242行调用方法'Total'时，即string acidPopsCost = cf.format（Total（1,5.95，acidPopsTF））;你实际上是在引用原始的JTextField对象'acidPopsTF'，它是null并且没有被初始化，这就是为什么第＃329行抛出了一个nullpointer异常。
因此，不是使用verticalBuilder / horizontalBuilder方法，而是首先初始化对象，然后将其添加到面板中。 e.g -
picLabel = new JLabel(new ImageIcon(IMAGE_URL)),SwingConstants.CENTER);
acidPopsCard.add(picLabel, BorderLayout.PAGE_START);
acidPopsCard.add(new JLabel(YOUR_HTML_STRING), BorderLayout.CENTER);
acidPopsTF = new JTextField();
acidPopsCard.add(acidPopsTF,BorderLayout.PAGE_END);
看看@ line＃302你使用了cauldronCakesCost而不是crystalPineappleCost，它可以再次改变结果。
进行更改后，我确信您可以看到预期的结果。