问题
Please refer to the most updated post, which is this one, for further comments.
So there's this program I'm working on where I'm trying to make the user enter their input through a textbox in a JPanel.
btw, everything worked when I had it taking input from System.in with Scanner. Something about the change involving textField that's causing the problem. I have the "main" on another program, so that's not the problem either.
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUI extends JPanel implements ActionListener {
LinkedList<FoodItem> foodItemList = new LinkedList<FoodItem>();
CategoryList<String> categoryList = new CategoryList<String>();
Scanner in = new Scanner(System.in);
protected JButton[] buttons = new JButton[6];
String[] buttonNames = {"Add Item", "Remove Item", "Search for Item", "Update Item", "Check if List is Empty", "Print Items"};
String[] buttonCommands = {"add", "remove", "search", "update", "isEmpty", "print"};
protected JTextField textField;
public GUI() {
textField = new JTextField(20);
textField.addActionListener(this);
add(textField);
for (int i = 0; i < 6; i++) {
buttons[i] = new JButton(buttonNames[i]);
buttons[i].setActionCommand(buttonCommands[i]);
buttons[i].setVerticalTextPosition(AbstractButton.CENTER);
buttons[i].setHorizontalTextPosition(AbstractButton.LEADING);
buttons[i].addActionListener(this);
add(buttons[i]);
}
}
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if (command.equals(buttonCommands[0]))
add();
else if (command.equals(buttonCommands[1]))
remove();
else if (command.equals(buttonCommands[2]))
search();
else if (command.equals(buttonCommands[3]))
update();
else if (command.equals(buttonCommands[4]))
isEmpty();
else
print();
}
public void add() {
System.out.println("Please enter the name of the product you want to add.");
String text = textField.getText();
try {
if (foodItemList.containsName(text))
throw new DuplicateProductException();
else
foodItemList.add(enterFoodItem(text));
}
catch(DuplicateProductException ex) {
System.out.println("The product has already been added to the list.");
System.out.println("Would you like to update or remove this item? (U for update, R for remove, N for neither)");
String response = textField.getText();
if (response.equals("U"))
update();
if (response.equals("R"))
remove();
}
}
public void remove(String s) {
if (foodItemList.size() == 1)
foodItemList.list = null;
else
foodItemList.oneBeforeContainingName(s).setLink(foodItemList.oneBeforeContainingName(s).getLink().getLink());
System.out.println("The product has been removed.");
}
public void remove() {
System.out.println("Please enter the name of the product you want to remove.");
String text = textField.getText();
try {
if (foodItemList.containsName(text))
remove(text);
else
throw new NonexistentProductException();
}
catch(NonexistentProductException ex) {
System.out.println("The product does not exist in the list.");
System.out.println("Would you like to add this product? (Y/N)");
String response = in.nextLine();
if (response.equals("Y"))
add();
}
}
public void search() {
System.out.println("Please enter the name of the product you want to search for.");
String text = textField.getText();
if (foodItemList.containsName(text)) {
System.out.println("The product is found.");
System.out.println("Would you like to print it or update it? (P for print, U for update, N for neither)");
String response = in.nextLine();
if (response.equals("P"))
print(text);
if (response.equals("U"))
update(text);
}
else
System.out.println("The product does not exist in the list.");
}
public void update(String s){
foodItemList.nodeContainingName(s).setElement(enterFoodItem(s));
}
public void update() {
System.out.println("Please enter the name of the product you want to update.");
String text = textField.getText();
try {
if (foodItemList.containsName(text))
update(text);
else
throw new NonexistentProductException();
}
catch(NonexistentProductException ex) {
System.out.println("The product does not exist in the list.");
System.out.println("Would you like to add this product? (Y/N)");
String response = in.nextLine();
if (response.equals("Y"))
add();
}
}
public void isEmpty() {
if (foodItemList.isEmpty())
System.out.println("The list is empty.");
else
System.out.println("The list is not empty.");
}
public void print(String s){
LinkedListNode<FoodItem> temp = foodItemList.list;
while (!temp.getElement().name.equals(s))
temp = temp.getLink();
System.out.println(temp.getElement().toString());
}
public void print() {
if (foodItemList.isEmpty())
System.out.println("The list is empty.");
else
System.out.println("Here is the list:" + foodItemList.toString());
}
public FoodItem enterFoodItem(String input) {
String[] requiredEntry = {"price", "quantity", "description", "size", "special order", "category"};
double p = 0.0;
int q = 0;
String d = "";
double s = 0.0;
String so = "";
String c = "";
for (int i = 0; i < 6; i++) {
System.out.println("Please enter the " + requiredEntry[i] + " of the product.");
if (i == 0)
p = Double.parseDouble(textField.getText());
if (i == 1)
q = Integer.parseInt(textField.getText());
if (i == 2)
for (int j = 0; j < 2; j++)
d = textField.getText();
if (i == 3)
s = Double.parseDouble(textField.getText());
if (i == 4)
for (int j = 0; j < 2; j++)
so = textField.getText();;
if (i == 5)
c = textField.getText();
}
return new FoodItem(input,p,q,d,s,so,c);
}
public class DuplicateProductException extends Exception {
public DuplicateProductException() {;}
}
public class NonexistentProductException extends Exception {
public NonexistentProductException() {;}
}
public static void createAndShowGUI() {
JFrame frame = new JFrame("Vendor Interface");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GUI newContentPane = new GUI();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
}
Sorry it's probably too long (and this is only one program among many in a project...), but to get to the core of the problem, when the buttons come up, I'm supposed to be able to enter the name of the product first. But for some reason it "skips" over not only the name, but also the price. This is the error I'm getting:
Please enter the name of the product you want to add.
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
Please enter the price of the product.
at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
at java.lang.Double.parseDouble(Unknown Source)
at GUI.enterFoodItem(GUI.java:150)
at GUI.add(GUI.java:49)
at GUI.actionPerformed(GUI.java:30)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Again, I apologize for the gargantuan post, but I don't know how much of all this I would need to provide you all with enough info to find the bug in this program. Thank you very much in advance for the help!
来源：https://stackoverflow.com/questions/19127402/jtextfield-ignoring-a-nextline