Java2实用教程(第二版)程序代码——第六章 时间、日期和数字
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//例子1
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import java.util.Date;
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import java.text.SimpleDateFormat;
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class Example6_1
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{ public static void main(String args[])
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{ Date nowTime=new Date();
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System.out.println("现在的时间:"+nowTime);
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SimpleDateFormat matter1=new SimpleDateFormat("yyyy年MM月dd日 北京时间");
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System.out.println("现在的时间:"+matter1.format(nowTime));
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SimpleDateFormat matter2=
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new SimpleDateFormat("yyyy年MM月Edd日HH时mm分ss秒 北京时间");
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System.out.println("现在的时间:"+matter2.format(nowTime));
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SimpleDateFormat matter3=
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new SimpleDateFormat("北京时间dd日HH时MMM ss秒mm分EE");
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System.out.println("现在的时间:"+matter3.format(nowTime));
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}
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}
18![](/Images/OutliningIndicators/None.gif)
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//例子 2
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import java.util.Date;
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class Example6_2
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{ public static void main(String args[])
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{ long time1=System.currentTimeMillis();
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Date date=new Date(time1);
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System.out.println(date);
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String s=String.valueOf(time1);
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int length=s.length(); s=s.substring(length-8);
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System.out.println(s);
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long result=f(28);
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System.out.println("result="+result);
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long time2=System.currentTimeMillis();//计算f(28)之后的时间。
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s=String.valueOf(time2);
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length=s.length(); s=s.substring(length-8);
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System.out.println(s);
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System.out.println("用时:"+(time2-time1)+"毫秒");
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}
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public static long f(long n)
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{ long c=0;
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if(n==1||n==2) c=1;
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else if(n>=3) c=f(n-1)+f(n-2);
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return c;
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}
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}
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//例子 3
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import java.util.*;
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class Example6_3
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{ public static void main(String args[])
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{ Calendar calendar=Calendar.getInstance(); //创建一个日历对象。
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calendar.setTime(new Date()); //用当前时间初始化日历时间。
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String 年=String.valueOf(calendar.get(Calendar.YEAR)),
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月=String.valueOf(calendar.get(Calendar.MONTH)+1),
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日=String.valueOf(calendar.get(Calendar.DAY_OF_MONTH)),
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星期=String.valueOf(calendar.get(Calendar.DAY_OF_WEEK)-1);
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int hour=calendar.get(Calendar.HOUR_OF_DAY),
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minute=calendar.get(Calendar.MINUTE),
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second=calendar.get(Calendar.SECOND);
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System.out.println("现在的时间是:");
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System.out.println(""+年+"年"+月+"月"+日+"日 "+ "星期"+星期);
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System.out.println(""+hour+"时"+minute+"分"+second+"秒");
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calendar.set(1962,5,29); //将日历翻到1962年6月29日,注意5表示六月。
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long time1962=calendar.getTimeInMillis();
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calendar.set(2003,9,5); //将日历翻到2003年10月5日。9表示十月。
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long time2003=calendar.getTimeInMillis();
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long 相隔天数=(time2003-time1962)/(1000*60*60*24);
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System.out.println("2003年10月5日和1962年6月29日相隔"+相隔天数+"天");
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}
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}
70![](/Images/OutliningIndicators/None.gif)
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//例子 4
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import java.util.*;
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class Example6_4
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{ public static void main(String args[])
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{ System.out.println(" 日 一 二 三 四 五 六");
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Calendar 日历=Calendar.getInstance(); //创建一个日历对象。
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日历.set(2004,0,1); //将日历翻到2004年1月1日,注意0表示一月。
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//获取1日是星期几(get方法返回的值是1表示星期日,星期六返回的值是7):
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int 星期几=日历.get(Calendar.DAY_OF_WEEK)-1;
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String a[]=new String[星期几+31]; //存放号码的一维数组
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for(int i=0;i<星期几;i++)
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{ a[i]="**";
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}
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for(int i=星期几,n=1;i<星期几+31;i++)
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{ if(n<=9)
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a[i]=String.valueOf(n)+" ";
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else
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a[i]=String.valueOf(n) ;
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n++;
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}
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//打印数组:
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for(int i=0;i<a.length;i++)
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{ if(i%7==0)
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{ System.out.println(""); //换行。
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}
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System.out.print(" "+a[i]);
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}
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}
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}
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//例子 5
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import java.text.NumberFormat;
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class Example6_5
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{ public static void main(String args[])
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{ double a=Math.sqrt(5);
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System.out.println("格式化前:"+a);
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NumberFormat f=NumberFormat.getInstance();
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f.setMaximumFractionDigits(5);f.setMinimumIntegerDigits(3);
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String s=f.format(a);
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System.out.println("格式化后:"+s);System.out.println("得到的随机数:");
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int number=8;
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for(int i=1;i<=20;i++)
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{ int randomNumber=(int)(Math.random()*number)+1;//产生1到8之间的随机数。
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System.out.print(" "+randomNumber);
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if(i%10==0)
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System.out.println("");
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}
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}
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}
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