Java的学习03

今天依然记录一下，学习情况，可以看到自己每一天都在进步。

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

 /**
  * 测试时间对象和字符串之间的相互转换
  * DateFormat抽象类和SimpleDateFormat实现类
  * @author 小白
  *
  */

 public class TestDateFormat {
     public static void main(String[] args) throws ParseException {

         //把时间对象按照“格式字符串指定的格式”转成相应的字符串
         DateFormat df = new SimpleDateFormat("yyyy年MM月dd日  hh:mm:ss");
         String str = df.format(new Date(40000000));
         System.out.println(str);

         //把字符串按照“格式字符串指定的格式”转成相应的时间对象
         DateFormat df2 = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
         Date date = df2.parse("1983-05-10 10:44:34");
         System.out.println(date);

         //测试其他的格式字符。比如：利用D，获得本时间对象是所处年份的第几天
         DateFormat df3 = new SimpleDateFormat("D");
         String str3 = df3.format(new Date());
         System.out.println(str3);

     }

 }

 import java.util.Calendar;
 import java.util.Date;
 import java.util.GregorianCalendar;

 /**
  * 测试日期类的使用
  * @author 小白
  *
  */    

 public class Testcalender {
     public static void main(String[] args) {

         Calendar calendar = new GregorianCalendar(2999, 10, 9, 22, 10, 50);
         int year = calendar.get(Calendar.YEAR);
         int month = calendar.get(Calendar.MONTH);
         int day = calendar.get(Calendar.DATE);
         int weekday = calendar.get(Calendar.DAY_OF_WEEK);//星期几。1-7

         System.out.println(year);
         System.out.println(day);
         System.out.println(month);//0-11表示对应的月份，0是1月，1是2月，依次类推
         System.out.println(weekday);

         //设置日期的相关元素
         Calendar c2 = new GregorianCalendar();
         c2.set(Calendar.YEAR, 8012);

         System.out.println(c2);

         //日期的计算
         Calendar c3 = new GregorianCalendar();
         c3.add(Calendar.DATE, 100);
         System.out.println(c3);

         //日期对象和时间对象的转化
         Date d4 = c3.getTime();
         Calendar c4 = new GregorianCalendar();
         c4.setTime(new Date());

         printCalendar(c4);
     }

     public static void printCalendar(Calendar c){
         //打印：1918年10月10日  11：23：45 周三

         int year = c.get(Calendar.YEAR);
         int month = c.get(Calendar.MONTH)+1;
         int date = c.get(Calendar.DAY_OF_MONTH);
         int dayweek = c.get(Calendar.DAY_OF_WEEK);

         String dayweek2 = dayweek==0?"日":dayweek+"";
         int hour = c.get(Calendar.HOUR);
         int minte = c.get(Calendar.MINUTE);
         int second = c.get(Calendar.SECOND);

         System.out.println(year+"年"+month+"月"+date+"日"+hour+"时"+minte+"分"+second+"秒"+
                 "周"+dayweek2);

     }
 }

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

 /**
  * 可视化日历程序
  * @author 小白
  *
  */
 public class TestCalendar02 {
     public static void main(String[] args) throws ParseException {
         System.out.println("请输入日期（如：2010-10-20）：");
         Scanner scanner = new Scanner(System.in);
         String str = scanner.nextLine();

         DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
         Date date = df.parse(str);//时间对象
         Calendar c = new GregorianCalendar();
         c.setTime(date);
         int day = c.get(Calendar.DAY_OF_MONTH);
         int days = c.getActualMaximum(Calendar.DAY_OF_MONTH);

         System.out.println("日\t一\t二\t三\t四\t五\t六\t");

         c.set(Calendar.DAY_OF_MONTH, 1);        

         for(int i=0;i<c.get(Calendar.DAY_OF_WEEK)-1;i++){
             System.out.print("\t");
         }         

         for(int i=0;i<days;i++){

             if(c.get(Calendar.DAY_OF_MONTH)==day){
                 System.out.print(c.get(Calendar.DAY_OF_MONTH)+"*\t");
             }else{
                 System.out.print(c.get(Calendar.DAY_OF_MONTH)+"\t");
             }

             if(c.get(Calendar.DAY_OF_WEEK)==Calendar.SATURDAY){
                 System.out.println();//换行
             }

             c.add(Calendar.DAY_OF_MONTH, 1);
         }

     }
 }