退出框架时如何关闭我的程序

Question

我在关闭 GUI 时遇到了一些问题。我试过了

frame.setDefaultCloseOperation(JFrame.CLOSE_ON_EXIT);

我已尝试使用 DISPOSE_ON_EXIT，但无法正常工作。

当我在没有任何代码的情况下运行程序并单击“X”时，它会关闭窗口，但它仍在运行。

当我将该代码放入其中时，它将无法编译，并且出现此错误。

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous tree type: <any>
    at InvestmentFrame2.main(InvestmentFrame2.java:103)

我已尝试阅读此处以及其他网站上的建议。我用来学习这些东西的书并没有真正解释它的任何内容，只是在一些示例代码中提供了它所以我一直在尝试一些不同的建议。

我不知道是否需要导入其他内容或是否存在其他问题？

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

public class InvestmentFrame2 extends JFrame
{
    private static final int FRAME_WIDTH = 450;
    private static final int FRAME_HEIGHT = 250;

    private static final double DEFAULT_RATE = 0;
    private static final double INITIAL_BALANCE = 0;
    private static final double YEARS = 0;

    private JLabel rateLabel;
    private JLabel balanceLabel;
    private JLabel yearsLabel;

    private JTextField rateField;
    private JTextField balanceField;
    private JTextField yearsField;

    private JButton button;

    private JLabel resultLabel;
    private double balance;

    public InvestmentFrame2()
    {
        balance = INITIAL_BALANCE;
        resultLabel = new JLabel("Balance: " + balance);

        createTextField();
        createButton();
        createPanel();

        setSize(FRAME_WIDTH, FRAME_HEIGHT);
    }

    private void createTextField()
    {
        rateLabel = new JLabel("Interest Rate: ");
        balanceLabel = new JLabel("Account Balance: ");
        yearsLabel = new JLabel("Number of Years Saving: ");

        final int FIELD_WIDTH = 10;

        rateField = new JTextField(FIELD_WIDTH);
        rateField.setText ("" + DEFAULT_RATE);

        balanceField = new JTextField(FIELD_WIDTH);
        balanceField.setText("" + INITIAL_BALANCE);

        yearsField = new JTextField(FIELD_WIDTH);
        yearsField.setText("" + YEARS);
    }

    class AddInterestListener implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            double rate = Double.parseDouble(rateField.getText());
            double accountBalance = Double.parseDouble(balanceField.getText());
            double years = Double.parseDouble(yearsField.getText());
            double interest = (accountBalance * rate / 100) * years;
            balance = accountBalance + interest;
            resultLabel.setText("Balance: " + balance);
        }
    }

    private void createButton()
    {
        button = new JButton("Calculate Balance");

        ActionListener listener = new AddInterestListener();
        button.addActionListener(listener);
    }

    private void createPanel()
    {
        JPanel panel = new JPanel();
        panel.add(rateLabel);
        panel.add(rateField);

        panel.add(balanceLabel);
        panel.add(balanceField);

        panel.add(yearsLabel);
        panel.add(yearsField);

        panel.add(button);
        panel.add(resultLabel);
        add(panel);
    }

    public static void main(String[] args)
    {
        JFrame frame = new InvestmentFrame2();
        frame.setTitle("Savings Frame");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_EXIT);
        frame.setVisible(true);
    }
}

Answer 1

您正在尝试运行一个不可编译的类...JFrame.DISPOSE_ON_EXIT 不存在。你其实是在找JFrame.EXIT_ON_CLOSE

花一点时间阅读JavaDocs for JFrame

public void setDefaultCloseOperation(int operation)

设置 当用户启动一个默认操作 在这个框架上“关闭”。您必须指定以下其中一项 选择：

* DO_NOTHING_ON_CLOSE（在 WindowConstants 中定义）： 什么都不做；要求程序处理 已注册的 WindowListener 对象的 windowClosing 方法。
* HIDE_ON_CLOSE（在 WindowConstants 中定义）：自动隐藏 调用任何已注册的 WindowListener 对象后的帧。
* DISPOSE_ON_CLOSE（在WindowConstants中定义）：自动隐藏和 在调用任何已注册的 WindowListener 后处置框架 对象。
* EXIT_ON_CLOSE（在 JFrame 中定义）：退出 应用程序使用系统退出方法。仅在 应用程序。

默认情况下，该值设置为 HIDE_ON_CLOSE。 更改此属性的值会导致触发属性 更改事件，属性名称为“defaultCloseOperation”。

您可能还会发现 How to Make Frames (Main Windows) 有一些用处...

您还应该确保您的 UI 是在事件调度线程的上下文中创建的，请查看 Initial Threads 了解更多详细信息

更新示例

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

public class InvestmentFrame2 extends JFrame {

    private static final int FRAME_WIDTH = 450;
    private static final int FRAME_HEIGHT = 250;

    private static final double DEFAULT_RATE = 0;
    private static final double INITIAL_BALANCE = 0;
    private static final double YEARS = 0;

    private JLabel rateLabel;
    private JLabel balanceLabel;
    private JLabel yearsLabel;

    private JTextField rateField;
    private JTextField balanceField;
    private JTextField yearsField;

    private JButton button;

    private JLabel resultLabel;
    private double balance;

    public InvestmentFrame2() {
        balance = INITIAL_BALANCE;
        resultLabel = new JLabel("Balance: " + balance);

        createTextField();
        createButton();
        createPanel();

        setSize(FRAME_WIDTH, FRAME_HEIGHT);
    }

    private void createTextField() {
        rateLabel = new JLabel("Interest Rate: ");
        balanceLabel = new JLabel("Account Balance: ");
        yearsLabel = new JLabel("Number of Years Saving: ");

        final int FIELD_WIDTH = 10;

        rateField = new JTextField(FIELD_WIDTH);
        rateField.setText("" + DEFAULT_RATE);

        balanceField = new JTextField(FIELD_WIDTH);
        balanceField.setText("" + INITIAL_BALANCE);

        yearsField = new JTextField(FIELD_WIDTH);
        yearsField.setText("" + YEARS);
    }

    class AddInterestListener implements ActionListener {

        public void actionPerformed(ActionEvent event) {
            double rate = Double.parseDouble(rateField.getText());
            double accountBalance = Double.parseDouble(balanceField.getText());
            double years = Double.parseDouble(yearsField.getText());
            double interest = (accountBalance * rate / 100) * years;
            balance = accountBalance + interest;
            resultLabel.setText("Balance: " + balance);
        }
    }

    private void createButton() {
        button = new JButton("Calculate Balance");

        ActionListener listener = new AddInterestListener();
        button.addActionListener(listener);
    }

    private void createPanel() {
        JPanel panel = new JPanel();
        panel.add(rateLabel);
        panel.add(rateField);

        panel.add(balanceLabel);
        panel.add(balanceField);

        panel.add(yearsLabel);
        panel.add(yearsField);

        panel.add(button);
        panel.add(resultLabel);
        add(panel);
    }

    public static void main(String[] args) {
        JFrame frame = new InvestmentFrame2();
        frame.setTitle("Savings Frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

对我来说编译和运行都很好......