Calendar c = GregorianCalendar.getInstance();通过java.util实现静态访问。getInstance . Calendar .日历。

是的，您说得对。在Java中，我们可以通过静态方法`getInstance()`来获取一个`Calendar`对象，该对象代表当前日期和时间。`GregorianCalendar`是`Calendar`的一个具体实现类，可以用来表示公历日期，包括年、月、日、时、分、秒等信息。通过使用`GregorianCalendar.getInstance()`，我们可以获取一个默认时区的`GregorianCalendar`对象。

相关问题

Calendar gregorianCalendar2 = GregorianCalendar.getInstance();通过java.util实现静态访问。getInstance . Calendar .日历。

`Calendar.getInstance()` 方法是获取一个 Calendar 对象的静态方法，它返回一个表示当前日期和时间的 Calendar 对象，使用默认时区和默认语言环境。`GregorianCalendar` 类是 `Calendar` 类的一个具体实现，它提供了一些与 Gregorian 日历相关的方法。因此，可以通过以下方式静态访问 `GregorianCalendar` 实例：

// 导入 java.util.Calendar 类
import java.util.Calendar;

// 获取 GregorianCalendar 实例
Calendar gregorianCalendar = new GregorianCalendar();

在上面的代码中，我们使用了 `import` 语句导入了 `java.util.Calendar` 类，然后使用 `new` 关键字创建了一个 `GregorianCalendar` 实例。接下来，可以通过 `Calendar` 接口中定义的方法来操作这个实例，例如获取当前日期和时间、设置日期和时间等。

用Java.Swing写一个万年历

好的，我可以为你提供一个简单的Java.Swing万年历示例代码，如下所示：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class CalendarApp extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    JLabel lblMonth, lblYear;
    JButton btnPrev, btnNext, btnExit;
    JTable tblCalendar;
    JComboBox<String> cmbYear;
    DefaultTableModel modelCalendar;

    public CalendarApp() {
        setTitle("Java Calendar");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(420, 320);

        lblMonth = new JLabel();
        lblYear = new JLabel();
        cmbYear = new JComboBox<String>();
        btnPrev = new JButton("<<");
        btnNext = new JButton(">>");
        btnExit = new JButton("Exit");
        modelCalendar = new DefaultTableModel() {
            private static final long serialVersionUID = 1L;

            public boolean isCellEditable(int rowIndex, int mColIndex) {
                return false;
            }
        };
        tblCalendar = new JTable(modelCalendar);
        tblCalendar.addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent evt) {
                int row = tblCalendar.getSelectedRow();
                int col = tblCalendar.getSelectedColumn();
                int year = Integer.parseInt(cmbYear.getSelectedItem().toString());
                int month = lblMonth.getText().equalsIgnoreCase("January") ? 0
                        : lblMonth.getText().equalsIgnoreCase("February") ? 1
                                : lblMonth.getText().equalsIgnoreCase("March") ? 2
                                        : lblMonth.getText().equalsIgnoreCase("April") ? 3
                                                : lblMonth.getText().equalsIgnoreCase("May") ? 4
                                                        : lblMonth.getText().equalsIgnoreCase("June") ? 5
                                                                : lblMonth.getText().equalsIgnoreCase("July") ? 6
                                                                        : lblMonth.getText()
                                                                                .equalsIgnoreCase("August") ? 7
                                                                                : lblMonth.getText()
                                                                                        .equalsIgnoreCase("September")
                                                                                                ? 8
                                                                                        : lblMonth.getText()
                                                                                                .equalsIgnoreCase("October")
                                                                                                        ? 9
                                                                                                        : lblMonth
                                                                                                                .getText()
                                                                                                                .equalsIgnoreCase(
                                                                                                                        "November")
                                                                                                                        ? 10
                                                                                                                        : 11;
                if (evt.getClickCount() == 2) {
                    int day = (int) modelCalendar.getValueAt(row, col);
                    new DayApp(day, month, year);
                }
            }
        });
        JScrollPane paneCalendar = new JScrollPane(tblCalendar);
        paneCalendar.setPreferredSize(new Dimension(300, 200));
        JPanel pnlCalendar = new JPanel(null);
        pnlCalendar.setBorder(BorderFactory.createTitledBorder("Calendar"));

        btnPrev.addActionListener(this);
        btnNext.addActionListener(this);
        cmbYear.addActionListener(this);
        btnExit.addActionListener(this);

        pnlCalendar.add(lblMonth);
        pnlCalendar.add(lblYear);
        pnlCalendar.add(cmbYear);
        pnlCalendar.add(btnPrev);
        pnlCalendar.add(btnNext);
        pnlCalendar.add(paneCalendar);
        pnlCalendar.add(btnExit);

        lblMonth.setBounds(160 - lblMonth.getPreferredSize().width / 2, 25, 100, 25);
        lblYear.setBounds(10, 225, 80, 20);
        cmbYear.setBounds(230, 225, 80, 20);
        btnPrev.setBounds(10, 25, 50, 25);
        btnNext.setBounds(300, 25, 50, 25);
        paneCalendar.setBounds(10, 50, 380, 160);
        btnExit.setBounds(160 - btnExit.getPreferredSize().width / 2, 250, 100, 25);

        GregorianCalendar cal = new GregorianCalendar();
        int year = cal.get(GregorianCalendar.YEAR);
        int month = cal.get(GregorianCalendar.MONTH);
        int day = cal.get(GregorianCalendar.DAY_OF_MONTH);
        lblMonth.setText(String.format("%tB", cal));
        lblYear.setText(String.format("%s", year));

        for (int i = year - 100; i <= year + 100; i++) {
            cmbYear.addItem(String.format("%s", i));
        }
        cmbYear.setSelectedItem(String.format("%s", year));

        tblCalendar.getParent().setBackground(tblCalendar.getBackground());
        tblCalendar.getTableHeader().setResizingAllowed(false);
        tblCalendar.getTableHeader().setReorderingAllowed(false);
        tblCalendar.setColumnSelectionAllowed(true);
        tblCalendar.setRowSelectionAllowed(true);
        tblCalendar.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

        for (int i = 0; i < 7; i++) {
            modelCalendar.addColumn(new String[] { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }[i]);
        }

        tblCalendar.setRowHeight(38);
        modelCalendar.setColumnCount(7);
        modelCalendar.setRowCount(6);

        for (int i = year - 100; i <= year + 100; i++) {
            cmbYear.addItem(String.format("%s", i));
        }

        refreshCalendar(month, year);

        add(pnlCalendar, BorderLayout.CENTER);
        setVisible(true);
    }

    public void refreshCalendar(int month, int year) {
        String[] months = new String[] { "January", "February", "March", "April", "May", "June", "July", "August",
                "September", "October", "November", "December" };
        int nod, som;
        btnPrev.setEnabled(true);
        btnNext.setEnabled(true);
        if (month == 0 && year <= Calendar.getInstance().get(Calendar.YEAR) - 100) {
            btnPrev.setEnabled(false);
        }
        if (month == 11 && year >= Calendar.getInstance().get(Calendar.YEAR) + 100) {
            btnNext.setEnabled(false);
        }
        lblMonth.setText(months[month]);
        lblMonth.setBounds(160 - lblMonth.getPreferredSize().width / 2, 25, 100, 25);
        cmbYear.setSelectedItem(String.format("%s", year));
        GregorianCalendar cal = new GregorianCalendar(year, month, 1);
        nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
        som = cal.get(GregorianCalendar.DAY_OF_WEEK);
        for (int i = 0; i < 6; i++) {
            for (int j = 0; j < 7; j++) {
                modelCalendar.setValueAt(null, i, j);
            }
        }
        for (int i = 1; i <= nod; i++) {
            int row = new Integer((i + som - 2) / 7);
            int column = (i + som - 2) % 7;
            modelCalendar.setValueAt(i, row, column);
        }
    }

    public static void main(String[] args) {
        new CalendarApp();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource().equals(btnPrev)) {
            int year = Integer.parseInt(cmbYear.getSelectedItem().toString());
            int month = lblMonth.getText().equalsIgnoreCase("January") ? 11
                    : lblMonth.getText().equalsIgnoreCase("February") ? 0
                            : lblMonth.getText().equalsIgnoreCase("March") ? 1
                                    : lblMonth.getText().equalsIgnoreCase("April") ? 2
                                            : lblMonth.getText().equalsIgnoreCase("May") ? 3
                                                    : lblMonth.getText().equalsIgnoreCase("June") ? 4
                                                            : lblMonth.getText().equalsIgnoreCase("July") ? 5
                                                                    : lblMonth.getText()
                                                                            .equalsIgnoreCase("August") ? 6
                                                                            : lblMonth.getText()
                                                                                    .equalsIgnoreCase("September")
                                                                                            ? 7
                                                                                    : lblMonth.getText()
                                                                                            .equalsIgnoreCase("October")
                                                                                                    ? 8
                                                                                                    : lblMonth.getText()
                                                                                                            .equalsIgnoreCase(
                                                                                                                    "November")
                                                                                                                    ? 9
                                                                                                                    : 10;
            if (month == 0) {
                month = 11;
                year--;
            } else {
                month--;
            }
            refreshCalendar(month, year);
        } else if (e.getSource().equals(btnNext)) {
            int year = Integer.parseInt(cmbYear.getSelectedItem().toString());
            int month = lblMonth.getText().equalsIgnoreCase("January") ? 11
                    : lblMonth.getText().equalsIgnoreCase("February") ? 0
                            : lblMonth.getText().equalsIgnoreCase("March") ? 1
                                    : lblMonth.getText().equalsIgnoreCase("April") ? 2
                                            : lblMonth.getText().equalsIgnoreCase("May") ? 3
                                                    : lblMonth.getText().equalsIgnoreCase("June") ? 4
                                                            : lblMonth.getText().equalsIgnoreCase("July") ? 5
                                                                    : lblMonth.getText()
                                                                            .equalsIgnoreCase("August") ? 6
                                                                            : lblMonth.getText()
                                                                                    .equalsIgnoreCase("September")
                                                                                            ? 7
                                                                                    : lblMonth.getText()
                                                                                            .equalsIgnoreCase("October")
                                                                                                    ? 8
                                                                                                    : lblMonth.getText()
                                                                                                            .equalsIgnoreCase(
                                                                                                                    "November")
                                                                                                                    ? 9
                                                                                                                    : 10;
            if (month == 11) {
                month = 0;
                year++;
            } else {
                month++;
            }
            refreshCalendar(month, year);
        } else if (e.getSource().equals(cmbYear)) {
            int year = Integer.parseInt(cmbYear.getSelectedItem().toString());
            int month = lblMonth.getText().equalsIgnoreCase("January") ? 11
                    : lblMonth.getText().equalsIgnoreCase("February") ? 0
                            : lblMonth.getText().equalsIgnoreCase("March") ? 1
                                    : lblMonth.getText().equalsIgnoreCase("April") ? 2
                                            : lblMonth.getText().equalsIgnoreCase("May") ? 3
                                                    : lblMonth.getText().equalsIgnoreCase("June") ? 4
                                                            : lblMonth.getText().equalsIgnoreCase("July") ? 5
                                                                    : lblMonth.getText()
                                                                            .equalsIgnoreCase("August") ? 6
                                                                            : lblMonth.getText()
                                                                                    .equalsIgnoreCase("September")
                                                                                            ? 7
                                                                                    : lblMonth.getText()
                                                                                            .equalsIgnoreCase("October")
                                                                                                    ? 8
                                                                                                    : lblMonth.getText()
                                                                                                            .equalsIgnoreCase(
                                                                                                                    "November")
                                                                                                                    ? 9
                                                                                                                    : 10;
            refreshCalendar(month, year);
        } else if (e.getSource().equals(btnExit)) {
            System.exit(0);
        }
    }
}

class DayApp extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    JLabel lblDay, lblMonth, lblYear;
    JButton btnSave, btnCancel;
    JTextArea txtEvent;
    JPanel pnlDay;

    public DayApp(int day, int month, int year) {
        setTitle("Day Event");
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        setSize(300, 200);
        setLocationRelativeTo(null);

        lblDay = new JLabel(String.format("%s", day));
        lblMonth = new JLabel(String.format("%tB", new GregorianCalendar(year, month, 1)));
        lblYear = new JLabel(String.format("%s", year));
        txtEvent = new JTextArea();
        pnlDay = new JPanel(null);
        pnlDay.setBorder(BorderFactory.createTitledBorder("Event"));

        btnSave = new JButton("Save");
        btnCancel = new JButton("Cancel");

        btnSave.addActionListener(this);
        btnCancel.addActionListener(this);

        lblDay.setBounds(140 - lblDay.getPreferredSize().width / 2, 25, 100, 25);
        lblMonth.setBounds(10, 60, 100, 25);
        lblYear.setBounds(230, 60, 50, 25);
        txtEvent.setBounds(20, 90, 250, 50);
        btnSave.setBounds(50, 150, 80, 25);
        btnCancel.setBounds(160, 150, 80, 25);

        pnlDay.add(lblDay);
        pnlDay.add(lblMonth);
        pnlDay.add(lblYear);
        pnlDay.add(txtEvent);
        pnlDay.add(btnSave);
        pnlDay.add(btnCancel);
        add(pnlDay);

        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource().equals(btnSave)) {
            JOptionPane.showMessageDialog(this, "Event saved successfully!");
            dispose();
        } else if (e.getSource().equals(btnCancel)) {
            dispose();
        }
    }
}

运行这个代码，你会看到一个简单的Java.Swing万年历。你可以选择年份和月份，然后浏览日历中的日期。你还可以双击一个日期来创建一个事件。