import java.util.*;
public class Test {
    public static void main(String[] args) {
        Date date;
        Calendar cal=Calendar.getInstance();
        cal.set(Calendar.YEAR, 2016);
        cal.set(Calendar.WEEK_OF_YEAR, 1);
        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        System.out.println("first week Monday is "+cal.getTime());
    }
}

输出结果，欢迎大家来答！不要翻日历:lol

import java.util.*;
public class Test {
    public static void main(String[] args) {
        Date date;
        Calendar cal=Calendar.getInstance();
        cal.set(Calendar.YEAR, 2016);
        cal.set(Calendar.WEEK_OF_YEAR, 1);
        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        System.out.println("first week Monday is "+cal.getTime());
    }
}

输出结果，欢迎大家来答！不要翻日历:lol