java calendar 時間

1、計算某一月份的最大天數

Calendar?time=Calendar.getInstance();?

time.clear();?

time.set(Calendar.YEAR,year);?

time.set(Calendar.MONTH,i-1);//注意,Calendar對象默認一月為0????????????

intday=time.getActualMaximum(Calendar.DAY_OF_MONTH);//本月份的天數

注：在使用set方法之前，必須先clear一下，否則很多信息會繼承自系統(tǒng)當前時間。

2、Calendar和Date的轉化

(1) Calendar轉化為Date

Calendar?cal=Calendar.getInstance();

Date?date=cal.getTime();

(2) Date轉化為Calendar

Date?date=new?Date();

Calendar?cal=Calendar.getInstance();

cal.setTime(date);

3、格式化輸出日期時間

Date?date=new?Date();

SimpleDateFormat?df=new?SimpleDateFormat("yyyy-MM-dd?hh:mm:ss");

System.out.println(df.format(date));

4、計算一年中的第幾星期

(1)計算某一天是一年中的第幾星期

Calendar?cal=Calendar.getInstance();

cal.set(Calendar.YEAR,?2006);

cal.set(Calendar.MONTH,?8);

cal.set(Calendar.DAY_OF_MONTH,?3);

int?weekno=cal.get(Calendar.WEEK_OF_YEAR);

(2)計算一年中的第幾星期是幾號

SimpleDateFormat?df=new?SimpleDateFormat("yyyy-MM-dd");

Calendar?cal=Calendar.getInstance();

cal.set(Calendar.YEAR,?2006);

cal.set(Calendar.WEEK_OF_YEAR,?1);

cal.set(Calendar.DAY_OF_WEEK,?Calendar.MONDAY);

System.out.println(df.format(cal.getTime()));

怎么用java寫日歷

以下是兩個類，請樓主分別存成兩個java文件:

其中

MainFrame.java是顯示日歷程序，Clock.java是日歷計算程序。編譯后運行MainFrame這個類即可。

1.MainFrame.java

---

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.GridLayout;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.sql.Date;

import java.util.Calendar;

import javax.swing.JComboBox;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

public class MainFrame extends JFrame {

/** *//**

*

*/

private static final long serialVersionUID = 1L;

JPanel panel = new JPanel(new BorderLayout());

JPanel panel1 = new JPanel();

JPanel panel2 = new JPanel(new GridLayout(7, 7));

JPanel panel3 = new JPanel();

JLabel[] label = new JLabel[49];

JLabel y_label = new JLabel("年份");

JLabel m_label = new JLabel("月份");

JComboBox com1 = new JComboBox();

JComboBox com2 = new JComboBox();

int re_year, re_month;

int x_size, y_size;

String year_num;

Calendar now = Calendar.getInstance(); // 實例化Calendar

MainFrame() {

super("萬年歷");

setSize(300, 350);

x_size = (int) (Toolkit.getDefaultToolkit().getScreenSize().getWidth());

y_size = (int) (Toolkit.getDefaultToolkit().getScreenSize().getHeight());

setLocation((x_size - 300) / 2, (y_size - 350) / 2);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

panel1.add(y_label);

panel1.add(com1);

panel1.add(m_label);

panel1.add(com2);

for (int i = 0; i 49; i++) {

label[i] = new JLabel("", JLabel.CENTER);// 將顯示的字符設置為居中

panel2.add(label[i]);

}

panel3.add(new Clock(this));

panel.add(panel1, BorderLayout.NORTH);

panel.add(panel2, BorderLayout.CENTER);

panel.add(panel3, BorderLayout.SOUTH);

panel.setBackground(Color.white);

panel1.setBackground(Color.white);

panel2.setBackground(Color.white);

panel3.setBackground(Color.white);

Init();

com1.addActionListener(new ClockAction());

com2.addActionListener(new ClockAction());

setContentPane(panel);

setVisible(true);

setResizable(false);

}

class ClockAction implements ActionListener {

public void actionPerformed(ActionEvent arg0) {

int c_year, c_month, c_week;

c_year = Integer.parseInt(com1.getSelectedItem().toString()); // 得到當前所選年份

c_month = Integer.parseInt(com2.getSelectedItem().toString()) - 1; // 得到當前月份，并減1,計算機中的月為0－11

c_week = use(c_year, c_month); // 調用函數use，得到星期幾

Resetday(c_week, c_year, c_month); // 調用函數Resetday

}

}

public void Init() {

int year, month_num, first_day_num;

String log[] = { "日", "一", "二", "三", "四", "五", "六" };

for (int i = 0; i 7; i++) {

label[i].setText(log[i]);

}

for (int i = 0; i 49; i = i + 7) {

label[i].setForeground(Color.red); // 將星期日的日期設置為紅色

}

for (int i = 6; i 49; i = i + 7) {

label[i].setForeground(Color.green);// 將星期六的日期設置為綠色

}

for (int i = 1; i 10000; i++) {

com1.addItem("" + i);

}

for (int i = 1; i 13; i++) {

com2.addItem("" + i);

}

month_num = (int) (now.get(Calendar.MONTH)); // 得到當前時間的月份

year = (int) (now.get(Calendar.YEAR)); // 得到當前時間的年份

com1.setSelectedIndex(year - 1); // 設置下拉列表顯示為當前年

com2.setSelectedIndex(month_num); // 設置下拉列表顯示為當前月

first_day_num = use(year, month_num);

Resetday(first_day_num, year, month_num);

}

public int use(int reyear, int remonth) {

int week_num;

now.set(reyear, remonth, 1); // 設置時間為所要查詢的年月的第一天

week_num = (int) (now.get(Calendar.DAY_OF_WEEK));// 得到第一天的星期

return week_num;

}

@SuppressWarnings("deprecation")

public void Resetday(int week_log, int year_log, int month_log) {

int month_day_score; // 存儲月份的天數

int count;

month_day_score = 0;

count = 1;

Date date = new Date(year_log, month_log + 1, 1); // now

Calendar cal = Calendar.getInstance();

cal.setTime(date);

cal.add(Calendar.MONTH, -1); // 前個月

month_day_score = cal.getActualMaximum(Calendar.DAY_OF_MONTH);// 最后一天

for (int i = 7; i 49; i++) { // 初始化標簽

label[i].setText("");

}

week_log = week_log + 6; // 將星期數加6，使顯示正確

month_day_score = month_day_score + week_log;

for (int i = week_log; i month_day_score; i++, count++) {

label[i].setText(count + "");

}

}

public static void main(String[] args) {

JFrame.setDefaultLookAndFeelDecorated(true);

new MainFrame();

}

}

2.Clock.java

-----

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.GridLayout;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.sql.Date;

import java.util.Calendar;

import javax.swing.JComboBox;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

//顯示時間的類：Clock

/** *//**

* Clock.java

* Summary 數字時間顯示

* Created on

* @author

* remark

*/

import java.awt.Canvas;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.text.SimpleDateFormat;

import java.util.Calendar;

class Clock extends Canvas implements Runnable{

/** *//**

*

*/

private static final long serialVersionUID = 3660124045489727166L;

MainFrame mf;

Thread t;

String time;

public Clock(MainFrame mf){

this.mf=mf;

setSize(280,40);

setBackground(Color.white);

t=new Thread(this); //實例化線程

t.start(); //調用線程

}

public void run(){

while(true){

try{

Thread.sleep(1000); //休眠1秒鐘

}catch(InterruptedException e){

System.out.println("異常");

}

this.repaint(100);

}

}

public void paint(Graphics g){

Font f=new Font("宋體",Font.BOLD,16);

SimpleDateFormat SDF=new SimpleDateFormat("yyyy'年'MM'月'dd'日'HH:mm:ss");//格式化時間顯示類型

Calendar now=Calendar.getInstance();

time=SDF.format(now.getTime()); //得到當前日期和時間

g.setFont(f);

g.setColor(Color.orange);

g.drawString(time,45,25);

}

}

java 日歷的代碼問題

首先，控制臺輸入肯定要是形如2013-03-06這樣的格式，這是SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-DD")所要求的。輸入2013-03會進入異常處理提示輸入格式不正確。至于打印日歷，你可以算出該月的第一號是星期幾，然后按順序排下去，滿7天換行就是了