Question

java考试题目，求给答案

第十二届全运会将于2013年8月31日在辽宁举行，请用java的日期类可运行程序（类名Test），计算输出开幕式当天是星期几，最后使用字节输出流把获取的星期存储到“log.txt”日志文件中，并输出“log.txt”文件的长度。

Answer 1

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.util.Scanner;

/**
* 计算某天为星期几
* @author hf
*
*/
public class WeekDay
{
/**
*
* @param y 年
* @param m 月
* @param d 日
* @return
*/
public static String suan(int y,int m,int d)
{
if(m==1) {m=13;y--;}
if(m==2) {m=14;y--;}
int week=(d+2*m+3*(m+1)/5+y+y/4-y/100+y/400)%7;
String weekstr="";
switch(week)
{
case 0: weekstr="一"; break;
case 1: weekstr="二"; break;
case 2: weekstr="三"; break;
case 3: weekstr="四"; break;
case 4: weekstr="五"; break;
case 5: weekstr="六"; break;
case 6: weekstr="日"; break;
}
return weekstr;
}
public static void main(String[] args){
Scanner s=new Scanner(System.in);
System.out.println("请输入年月日");
int a=s.nextInt();
int b=s.nextInt();
int c=s.nextInt();
String s1=suan(a,b,c);
try {
File f = new File("E:\\123.txt");
if(f.exists()){
System.out.print("文件存在");
}else{
f.createNewFile();//不存在则创建
}
BufferedWriter output = new BufferedWriter(new FileWriter(f));
output.write(s1);
output.close();
System.out.println("文件的长度为："+new File("E:\\123.txt").length());
} catch (Exception e) {
e.printStackTrace();
}
}

}

Answer 2

public static void main(String[] args) {
  
Date date= new Date();
        SimpleDateFormat d= new SimpleDateFormat("yyyy-MM-dd");
        try {
            date= d.parse("2013-8-31"); //自己定义的时间
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("E");
            String  mydate=simpleDateFormat.format(date);// 
            System.out.println(mydate);
            
            FileOutputStream fos  = new FileOutputStream("log.txt");//会保存在你当前工程下，与你的test.java同级目录
            fos.write(mydate.getBytes("UTF-8"));
            fos.close();
            
            FileInputStream fr = new FileInputStream("log.txt");
            byte[] buf = new byte[1024];
            int len = fr.read(buf);
            System.out.println(len);// 你要的长度
            
            String myStr = new String(buf,0,len,"UTF-8");
            System.out.println(myStr); // 重新读取log.txt内容并输出
        } catch (Exception e) {
            e.printStackTrace();
        }
}

Answer 3

public static void main(String[] args) throws ParseException, IOException {
// TODO Auto-generated method stub
String[] weekDays={"星期日","星期一","星期二","星期三","星期四","星期五","星期六"};
//char[] weekDaysC = {'1','12'};
String date = "2013-08-31";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();
c.setTime(sdf.parse(date));
int w =c.get(Calendar.DAY_OF_WEEK)-1;
if(w<0){
w=0;
}
out(weekDays[w])
}
public void out(String weekDays)throws ParseException, IOException{
File outFile= new File("log.txt");
try {
FileOutputStream out= new FileOutputStream(outFile);
OutputStreamWriter ow = new OutputStreamWriter(out);
ow.write(weekDays);
ow.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}