Integer.parseInt(this.month)是什么意思

`Integer.parseInt(this.month)` 是将字符串类型的 `this.month` 转换为整数类型的方法。其中，`this.month` 是一个字符串，`parseInt` 是将字符串转换成整数的方法，它会将字符串解析成一个有符号的十进制整数。如果 `this.month` 不是一个合法的数字字符串，那么该方法会抛出一个 `NumberFormatException` 异常。

相关问题

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。

以下程序能否编译成功？如果能，写出程序的执行过程和执行结果；如果不能， 说明错误原因并修改代码 1. class StringDemo{ public static void main(String[] args){ String s1 = “a”; String s2 = “b”; show(s1,s2); System.out.println(s1+s2); } public static void show(String s1,String s2){ s1 = s1 +“q”; s2 = s2 + s1; } } 2. public class TestMonth{ public static void main(String []args){ try{ int month=Integer. parseInt("13"); if(month<0||month>12){ throw new ArithmeticException("没有"+month+"月份！"); } System.out.println("您输入的月份为"+month+"月份"); }catch(ArrayIndexOutOfBoundsException e){ System.out.println("请输入月份!"); }catch(ArithmeticException e){ System.out.println("捕获 ArithmeticException 异常"); System.out.println(e.toString()); } } } 3. class Test{ public void stringReplace(String text){ text= text.replace('j','i'); text=text+"C"; } public void bufferReplace(StringBuffer text){ text.setCharAt(0,'i'); text=text.append("C"); } public void change(char ch[]) { ch[0]='Y'; } public static void main(String args[]){ String str1="java"; StringBuffer str2=new StringBuffer("java"); char ch[]={'j','a','v','a'}; Test t=new Test(); t.change(ch); t.stringReplace(str1); t.bufferReplace(str2); System.out.println(str1); System.out.println(str2.toString()); System.out.println (new String(ch)); } } 4. class Test{ public static String stringReplace(String text){ text=text.replace('j','i'); text=text+"C"; return text; } public static StringBuffer bufferReplace(StringBuffer text){ text.setCharAt(0,'i'); text= text.append("C"); return text; } public static void main(String aargs[]){ String str1="java"; String str2="java"; String str3="j"+"a"+"v"+"a"; String str4=new String("java"); StringBuffer str5=new StringBuffer("java"); System.out.println(str1==str2); System.out.println(str2==str3); System.out.println(str2==str4); System.out.println(str3.equals(str4)); System.out.println(str4.equals(str5)); System.out.println (stringReplace(str1)); System.out.println(bufferReplace(str5)); System.out.println(str1); System.out.println(str5); } } 5. interface Shape{ double PI; public double area(); public double perimeter(); } class Cycle extends Shape{ private double r; public Cycle(double r){ this.r=r; } double area(){ System.out.println(PI*r*r); } } public class Test{ public static void main(String args[]){ Cycle c=new Cycle(1.5); System.out.println("面积为："+c.area()); } }

1. 可以编译成功。执行过程为：首先定义了两个字符串 s1 和 s2，然后调用 show 方法，将 s1 和 s2 传入。在 show 方法中，对 s1 进行了拼接，并将拼接结果赋值给了 s1，对 s2 进行了拼接并将拼接结果赋值给了 s2，但是这两个操作对原来的 s1 和 s2 没有影响。最后在 main 方法中打印 s1 和 s2 的拼接结果，输出为 "ab"。
2. 可以编译成功。执行过程为：首先将字符串 "13" 转换成整型数 month，由于 month 大于 12，所以抛出 ArithmeticException 异常，被 catch 语句块捕获，输出 "捕获 ArithmeticException 异常" 和异常信息 "没有13月份！"。
3. 可以编译成功。执行结果为：stringReplace 方法中对传入的字符串进行了替换和拼接的操作，但由于 Java 中字符串是不可变的，所以对 text 的修改并没有影响。bufferReplace 方法中对传入的 StringBuffer 对象进行了替换和拼接的操作，成功修改了字符串，返回值也是修改后的字符串。change 方法中对数组 ch 的第一个元素进行了修改，由于数组是引用类型，所以修改成功。最终输出为：java、iavaC、Yava。
4. 可以编译成功。执行结果为：首先定义了五个字符串，其中 str1、str2 和 str3 都是指向字符串常量池中同一个字符串 "java" 的引用，str4 是指向堆内存中新创建的一个字符串对象的引用，str5 是指向堆内存中新创建的一个 StringBuffer 对象的引用。接着依次输出了一些比较结果，其中 str1==str2 的结果为 true，表示它们是同一个对象；str2==str3 的结果为 true，表示它们也是同一个对象；str2==str4 的结果为 false，因为它们指向不同的对象；str3.equals(str4) 的结果为 true，表示它们的值相等；str4.equals(str5) 的结果为 false，因为它们的类型不同。最后依次输出了 stringReplace、bufferReplace、str1 和 str5 的值。
5. 不能编译成功。在 Shape 接口中定义的 PI 没有初始化，应该改为 double PI = 3.1415926;。另外，Cycle 类应该继承抽象类 Shape，并实现 Shape 中的抽象方法 area 和 perimeter。area 方法应该返回计算好的圆的面积。最终执行结果为：面积为：7.0685834705770345。下面是修改后的代码：

interface Shape{
    double PI = 3.1415926;
    public double area();
    public double perimeter();
}

abstract class Shape {
    public abstract double area();
    public abstract double perimeter();
}

class Cycle extends Shape {
    private double r;
    public Cycle(double r){
        this.r = r;
    }
    public double area(){
        return PI*r*r;
    }
    public double perimeter() {
        return 2*PI*r;
    }
}

public class Test{
    public static void main(String args[]){
        Cycle c = new Cycle(1.5);
        System.out.println("面积为：" + c.area());
    }
}