Java如何顯示一年的週數？

在Java中，如何查詢一年中或一個月中的第幾個星期？

以下範例顯示年份和月份的第幾週。

package com.yiibai;
import java.util.*;

public class DisplayWeekNumber {
    public static void main(String[] args) throws Exception {
        Date d1 = new Date();
        Calendar cl = Calendar.getInstance();
        cl.setTime(d1);

        System.out.println("today is " + cl.WEEK_OF_YEAR + " week of the year");
        System.out.println("today is a " + cl.DAY_OF_MONTH
                + "month of the year");
        System.out.println("today is a " + cl.WEEK_OF_MONTH
                + "week of the month");
    }
}

上述程式碼範例將產生以下結果。

today is 3 week of the year
today is a 5month of the year
today is a 4week of the month

範例-2
以下是一年中的一個月的一個例子。

package com.yiibai;
import java.util.Calendar;
public class DisplayWeekNumber2 {
    public static void main(String[] args) {
        Calendar cal = Calendar.getInstance();
        System.out.println("Current week of month is : "
                + cal.get(Calendar.WEEK_OF_MONTH));
        System.out.println("Current week of year is : "
                + cal.get(Calendar.WEEK_OF_YEAR));
        cal.add(Calendar.WEEK_OF_MONTH, 1);
        System.out.println("date after one year : "
                + (cal.get(Calendar.MONTH) + 1) + "-" + cal.get(Calendar.DATE)
                + "-" + cal.get(Calendar.YEAR));
    }
}

上述程式碼範例將產生以下結果。

Current week of month is : 4
Current week of year is : 38
date after one year : 9-24-2017