我试图创建一个具有两个JTables的gui。一个输出对象自行车(如果可以的话)和一个输出对象出租。然而,缺省表模型总是返回空点异常。如何使用arraylist值填充JTable,然后将其添加到JPanel网格布局中。
我试图使用默认的表模型和表模型,以及搜索解决方案无效。这是一个基本的GUI学校项目
public static final ArrayList<Bike> bikes = new ArrayList<>();
public static final ArrayList<Customer> customers = new ArrayList<>();
public static final ArrayList<Rent> rents = new ArrayList<>();
ArrayList<Rent> toRemove = new ArrayList<Rent>();
//Create variables
private int customerID = 0;
private final LocalDate currentDate = LocalDate.now();
//Main Method
public static void main(String args[]) {
//Create gui
GUI fr = new GUI();
fr.setSize(1000, 600);
fr.setVisible(true);
fr.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
//Create Initial Objects and fill Arrays
bikes.add(new Bike("Tarmac Disk Expert", 6000.00, "Mountain", true));
bikes.add(new Bike("Epic Hardtail Comp", 3500.00, "Mountain", true));
bikes.add(new Bike("Chisel Comp", 2000.00, "Road", true));
bikes.add(new Bike("Roubaix Sport", 3500.00, "Road", false));
bikes.add(new Bike("Turbo Levi Comp", 9500.00, "City", false));
bikes.add(new Bike("Venge Pro", 9400.00, "City", true));
bikes.add(new EBike("Turbo Como 2.0 650B", 4500.00, "Ebike", true, "Full Power"));
bikes.add(new EBike("Turbo Kenevo Expert", 9500.00, "Ebike", true, "Full Power"));
bikes.add(new EBike("Turbo Levo FSR", 5600.00, "Ebike", true, "Full Power"));
bikes.add(new EBike("Turbo Vado 4.0", 5600.00, "Ebike", true, "Power Assisted"));
bikes.add(new EBike("S-Works Turbo Levo", 4000.00, "Ebike", true, "Power Assisted"));
bikes.add(new EBike("Turbo Como 2.0 Low Entry", 6600.00, "Ebike", true, "Power Assisted"));
customers.add(new Customer(0001, "John Smith", true, "Roubaix Sport"));
customers.add(new Customer(0002, "Madamn Tuscoue", false, "N/A"));
customers.add(new Customer(0003, "James Lafroix", true, "Turbo Levi Comp"));
rents.add(new Rent(0001, "John Smith", true, "Roubaix Sport", LocalDate.of(2019, 03, 06), LocalDate.of(2019, 04, 05), 30, true));
rents.add(new Rent(0003, "James Lafroix", true, "Turbo Levi Comp", LocalDate.of(2019, 03, 20), LocalDate.of(2019, 04, 19), 30, false));
public Bike(String name, double price, String type, boolean available) {
this.name = name;
this.price = price;
this.type = type;
this.available = available;
}
public Rent(int customerID, String customerName, boolean renting, String bikeRented, LocalDate startDate, LocalDate endDate, int duration, boolean overdue) {
super(customerID, customerName, renting, bikeRented);
this.startDate = startDate;
this.endDate = endDate;
this.duration = duration;
this.overdue = overdue;
}
public class GUI extends JFrame {
BikeNow controller = new BikeNow();
JPanel headingPanel = new JPanel();
JPanel centerPanel = new JPanel();
JPanel saveDetailsPanel = new JPanel();
JPanel customerPanel = new JPanel();
JPanel bikePanel = new JPanel();
JTable bikesAvaliable, currentRents;
JButton btnaddCustomer, btnviewCustomer, btnaddRent, btnreturnRent, btnsaveFile, btnloadFile;
JLabel lblHeading = new JLabel("Welcome to Bike Now");
public GUI() {
super("Bike Now");
Font headingFont = new Font("Times New Roman", Font.BOLD, 60);
this.headingPanel.setLayout(new GridLayout(1, 1));
this.headingPanel.setBorder(new EmptyBorder(10, 10, 10, 10));
lblHeading.setHorizontalAlignment(JLabel.CENTER);
lblHeading.setFont(headingFont);
this.headingPanel.add(this.lblHeading);
this.add(this.headingPanel, "North");
String[] columnNames1 = {"Bike Name", "Cost Per Day", "Bike Type"};
String[] columnNames2 = {"Start Date", "End Date", "Duration", "OverDue", "Customer ID", "Customer Name", "Renting", "Bike Rented"};
DefaultTableModel model = (DefaultTableModel)bikesAvaliable.getModel();
Object rowData[] = new Object[3];
for (int i = 0; i < controller.bikes.size(); i++) {
rowData[0] = controller.bikes.get(i).getName();
rowData[1] = controller.bikes.get(i).getPrice();
rowData[2] = controller.bikes.get(i).getType();
model.addRow(rowData);
}
bikesAvaliable.setModel(model);
//currentRents.setModel(tableModel2);
this.centerPanel.setLayout(new GridLayout(4, 1));
this.centerPanel.add(this.bikesAvaliable);
this.centerPanel.add(bikesAvaliable.getTableHeader());
//this.centerPanel.add(currentRents.getTableHeader());
//this.centerPanel.add(this.currentRents);
this.add(this.centerPanel, "Center");
}
}
出现在行处的NullPointError
DefaultTableModel model = (DefaultTableModel)bikesAvaliable.getModel();
在Gui类中
bikesAvaliable似乎没有在GUI类中为其分配对象。解决这个问题的一种方法是在gui类中创建您的bikesAvalible对象,或者将您在另一个类中创建的bikesAvaible对象传递给gui类,以便可以使用它。
作为一项任务,我被要求制作一个Swing GUI。在第一部分中,我创建了一个()对象()。目前所需要的是对所述数组列表进行排序,并将其显示为GUI中的。我制作了一个,当按下它时,它应该进行排序和显示。 但是,一旦按下它将只显示表标题而不显示数组列表中的信息,我应该做什么不同的事情呢?我已经在下面包括了GUI类和main类。
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它是从哪里来的?