java.awt.EventDispatchThread.pumpEvents是什么意思？

Question

我们的GUI代码存在问题。当我们运行它时会发生几个错误，我们不知道它们的含义。我们正在从模型创建一个订单系统，然后我们必须包含一个我们在Window构建器中构建的接口。对java编程很新，所以我们需要得到所有帮助：D谢谢。

GUI代码：

package ISprojekt3;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JTextArea;

public class OrderApplication {

    Controller1 controller = new Controller1();
    private JFrame frame;
    private JTextField name;
    private JTextField customerNumber;
    private JTextField address;
    private JTextField deliveryDate;
    private JTextField orderID;
    private JTextField number;
    private JTextField quantity;
    private JTextField nameProduct;
    private JTextField category;
    private JTextField price;
    private JTextField serialNumber;
    private JTextArea message;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    OrderApplication window = new OrderApplication();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public OrderApplication() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 672, 482);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(null);

        JLabel lblName = new JLabel("Namn:");
        lblName.setBounds(23, 45, 61, 16);
        frame.getContentPane().add(lblName);

        JLabel lblCustomerNumber = new JLabel("Kundnummer:");
        lblCustomerNumber.setBounds(23, 73, 106, 16);
        frame.getContentPane().add(lblCustomerNumber);

        JLabel lblAddress = new JLabel("Adress:");
        lblAddress.setBounds(23, 103, 61, 16);
        frame.getContentPane().add(lblAddress);

        JLabel lblCustomer = new JLabel("Kund");
        lblCustomer.setBounds(23, 17, 61, 16);
        frame.getContentPane().add(lblCustomer);

        name = new JTextField();
        name.setBounds(125, 40, 130, 26);
        frame.getContentPane().add(name);
        name.setColumns(10);

        customerNumber = new JTextField();
        customerNumber.setBounds(125, 68, 130, 26);
        frame.getContentPane().add(customerNumber);
        customerNumber.setColumns(10);

        address = new JTextField();
        address.setBounds(125, 98, 130, 26);
        frame.getContentPane().add(address);
        address.setColumns(10);

        JLabel lblOrder = new JLabel("Order");
        lblOrder.setBounds(313, 17, 61, 16);
        frame.getContentPane().add(lblOrder);

        JLabel lblOrderID = new JLabel("OrderID:");
        lblOrderID.setBounds(313, 45, 61, 16);
        frame.getContentPane().add(lblOrderID);

        JLabel lblDeliveryDate = new JLabel("Leveransdatum:");
        lblDeliveryDate.setBounds(313, 73, 106, 16);
        frame.getContentPane().add(lblDeliveryDate);

        deliveryDate = new JTextField();
        deliveryDate.setBounds(412, 68, 130, 26);
        frame.getContentPane().add(deliveryDate);
        deliveryDate.setColumns(10);

        orderID = new JTextField();
        orderID.setBounds(412, 40, 130, 26);
        frame.getContentPane().add(orderID);
        orderID.setColumns(10);

        JLabel lblOrderLine = new JLabel("Orderrad");
        lblOrderLine.setBounds(313, 159, 61, 16);
        frame.getContentPane().add(lblOrderLine);

        JLabel lblNumber = new JLabel("Nummer:");
        lblNumber.setBounds(313, 187, 61, 16);
        frame.getContentPane().add(lblNumber);

        JLabel lblQuantity = new JLabel("Antal produkter:");
        lblQuantity.setBounds(313, 215, 106, 16);
        frame.getContentPane().add(lblQuantity);

        number = new JTextField();
        number.setBounds(412, 182, 130, 26);
        frame.getContentPane().add(number);
        number.setColumns(10);

        quantity = new JTextField();
        quantity.setBounds(412, 210, 130, 26);
        frame.getContentPane().add(quantity);
        quantity.setColumns(10);

        JLabel lblProduct = new JLabel("Produkt");
        lblProduct.setBounds(23, 159, 61, 16);
        frame.getContentPane().add(lblProduct);

        JLabel lblName_2 = new JLabel("Namn:");
        lblName_2.setBounds(23, 187, 61, 16);
        frame.getContentPane().add(lblName_2);

        JLabel lblCategory = new JLabel("Kategori:");
        lblCategory.setBounds(23, 215, 61, 16);
        frame.getContentPane().add(lblCategory);

        nameProduct = new JTextField();
        nameProduct.setBounds(125, 187, 130, 26);
        frame.getContentPane().add(nameProduct);
        nameProduct.setColumns(10);

        category = new JTextField();
        category.setBounds(125, 215, 130, 26);
        frame.getContentPane().add(category);
        category.setColumns(10);

        price = new JTextField();
        price.setBounds(125, 238, 130, 26);
        frame.getContentPane().add(price);
        price.setColumns(10);

        JLabel lblPrice = new JLabel("Pris:");
        lblPrice.setBounds(23, 243, 61, 16);
        frame.getContentPane().add(lblPrice);

        JLabel lblCopy = new JLabel("Exemplar");
        lblCopy.setBounds(23, 297, 69, 16);
        frame.getContentPane().add(lblCopy);

        JLabel lblSerialNumber = new JLabel("Serienummer:");
        lblSerialNumber.setBounds(23, 325, 106, 16);
        frame.getContentPane().add(lblSerialNumber);

        serialNumber = new JTextField();
        serialNumber.setBounds(125, 320, 130, 26);
        frame.getContentPane().add(serialNumber);
        serialNumber.setColumns(10);

        JButton btnSearch = new JButton("Sök");
        btnSearch.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

            }
        });
        btnSearch.setBounds(409, 263, 117, 29);
        frame.getContentPane().add(btnSearch);

        JButton btnAdd = new JButton("Lägg till");
        btnAdd.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String customerName = name.getText();
                String customerNumber = number.getText();
                String customerAddress = address.getText();

                if((customerName.length() < 1) || (customerNumber.length() < 1) || (customerAddress.length() < 1)) {
                    message.setText("Tilläggning misslyckades");    
                }
                else {
                    controller.addCustomer(customerNumber, customerName, customerAddress);
                    message.setText("Kunden är tillagd");
                }

                String order = orderID.getText();
                String dDate = deliveryDate.getText();

                if((order.length() < 1 ) || (dDate.length() < 1)) {
                    message.setText("Tilläggning misslyckades");
                }
                else {
                    controller.addOrder(order, dDate, customerNumber);
                    message.setText("Ordern är tillagd till kund " + controller.findCustomer(customerNumber).getCustomerNumber());
                }

                String productName = nameProduct.getText();
                String productCategory = category.getText();
                String productPrice = price.getText();

                if((productName.length() < 1 ) || (productCategory.length() < 1 ) || (productPrice.length() < 1 )) {
                    message.setText("Tilläggning misslyckades");
                }
                else {
                    controller.addProduct(productName, productCategory, productPrice);
                    message.setText("Produkten är tillagd");
                }

                String orderLineNumber = number.getText();
                String orderLineQuantity = quantity.getText();

                if((orderLineNumber.length() < 1 ) || (orderLineQuantity.length() < 1)) {
                    message.setText("Tilläggning misslyckades");
                }
                else {
                    controller.addOrderLine(orderLineNumber, orderLineQuantity, order);
                    message.setText("Orderraden är tillagd i order" + controller.findOrder(order).getOrderID());
                }

                String serialNumberCopy = serialNumber.getText();

                if((serialNumberCopy.length() < 1)) {
                    message.setText("Tilläggningen misslyckades");
                }
                else {
                    controller.addCopy(serialNumberCopy, productName);
                    message.setText("Exemplaret är tillagd i produkt " + controller.findProduct(productName).getName());
                }
            }
        });
        btnAdd.setBounds(409, 292, 117, 29);
        frame.getContentPane().add(btnAdd);

        JButton btnRemove = new JButton("Ta bort");
        btnRemove.setBounds(409, 370, 117, 29);
        frame.getContentPane().add(btnRemove);

        JButton btnChange = new JButton("Ändra");
        btnChange.setBounds(409, 345, 117, 29);
        frame.getContentPane().add(btnChange);

        JTextArea message = new JTextArea();
        message.setBounds(23, 375, 231, 50);
        frame.getContentPane().add(message);
    }
}

以下是错误：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at ISprojekt3.OrderApplication$3.actionPerformed(OrderApplication.java:198)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6533)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6298)
    at java.awt.Container.processEvent(Container.java:2236)
    at java.awt.Component.dispatchEventImpl(Component.java:4889)
    at java.awt.Container.dispatchEventImpl(Container.java:2294)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
    at java.awt.Container.dispatchEventImpl(Container.java:2280)
    at java.awt.Window.dispatchEventImpl(Window.java:2746)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Answer 1

使用变量范围搞乱，使用的字段private JTextArea message未初始化。

创建的本地作用域JTextArea message = new JTextArea()从未分配到字段 message。