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);        }        }}