JAVA_常用类

//import java.text.SimpleDateFormat; //格式化日期
//import java.util.Calendar;   //日期
//import java.util.Date;     //时间
//import java.util.GregorianCalendar; //Calendar的子类

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class TestDate {
    public static void main(String[] args) throws ParseException {
        String strdate = "2019-10-19";
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        Calendar gc = new GregorianCalendar();
        Date date1 = df.parse(strdate);
        gc.setTime(date1); //  把一个日期设置到对象里面
        int days = gc.get(Calendar.DAY_OF_MONTH);  
        System.out.println("日\t一\t二\t三\t四\t五\t六");
        gc.set(Calendar.DAY_OF_MONTH,1);  //把日前设置成1号【因为要从1号打印】

        //补充几个空格
        for (int i=0;i < gc.get(Calendar.DAY_OF_WEEK)-1;i++){
            System.out.print("\t");
        }


        int maxday = gc.getActualMaximum(Calendar.DATE);
        gc.set(Calendar.DAY_OF_MONTH,1);   //设置成第一天
        for (int j = 1 ;j<maxday;j++){
            if (days ==gc.get(Calendar.DAY_OF_MONTH)){
                System.out.print(gc.get(Calendar.DAY_OF_MONTH)+"*"+"\t");
            }else{
            System.out.print(gc.get(Calendar.DAY_OF_MONTH)+"\t");}
            //循环的时候等于一周的时候换行
            if (gc.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY){ 
                System.out.println("");
            }
          gc.add(Calendar.DAY_OF_WEEK,1);
        }
        }
}