2016/5/22学习记录

1.关于Calenddar类的小程序

package Exercise;

import java.io.ObjectInputStream.GetField;
import java.time.DayOfWeek;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Random;

public class Stock {
    
    public static void main(String[] args) {
    Calendar i = new GregorianCalendar();
    display(i);
    i.add(Calendar.DAY_OF_YEAR, 100);
    display(i);

    }
    public static void display(Calendar k){
    String[] mon ={"一月","二月","三月","四月","五月","六月","七月","八月","九月","十月","十一月","十二月"};
    String[] we ={"星期一","星期二","星期三","星期四","星期五","星期六","星期天"};
    System.out.print(k.get(GregorianCalendar.YEAR)+"年");
    System.out.print(mon[k.get(GregorianCalendar.MONTH)]);
    System.out.print(k.get(GregorianCalendar.DAY_OF_MONTH)+"日");
    System.out.print(we[k.get(GregorianCalendar.DAY_OF_WEEK)]+"
");
    System.out.print(k.get(GregorianCalendar.HOUR)+":");
    System.out.print(k.get(GregorianCalendar.MINUTE)+":");
    System.out.print(k.get(GregorianCalendar.SECOND)+"
");
    }
}

2exercise 9.6

 1 import java.util.Date;
 2 import java.util.Random;
 3 
 4 public class StopWatch {
 5     private double starttime ;
 6     private double endtime ;
 7     public StopWatch() {
 8         starttime =System.currentTimeMillis();
 9     }
10     public void start(){
11         starttime =System.currentTimeMillis();
12     }
13     public void stop(){
14         endtime = System.currentTimeMillis();
15     }
16     public double gettime(){
17         return endtime-starttime;
18     }
19     
20     public static void main(String[] args) {
21         // TODO Auto-generated method stub
22     int[] a  = new int[1000];
23     Random t = new Random();
24     StopWatch sw = new StopWatch();
25     sw.start();
26     for(int k:a)
27     {k=t.nextInt(10000);}
28     int index=0;
29     for(int b=0;b<a.length-1;b++)
30     {
31         int ret=a[b];
32         for(int c=b+1;c<a.length;c++)
33         {
34             if(a[c]<ret)
35                 index=c;
36                 ret =a[c];
37         }
38         if(ret!=a[b])
39         {int temp = a[b];
40         a[b] = a[index];
41         a[index] = temp;}
42     }
43     sw.stop();
44     System.out.println(sw.gettime());
45     }
46     
47 }

注意选择排序的写法。要熟练。

3选择排序，非常简答的程序

 1 public static void selectSort(int[]a)
 2 {
 3     int minIndex=0;
 4     int temp=0;
 5     if((a==null)||(a.length==0))
 6         return;
 7     for(int i=0;i<a.length-1;i++)
 8     {
 9         minIndex=i;//无序区的最小数据数组下标
10         for(intj=i+1;j<a.length;j++)
11         {
12             //在无序区中找到最小数据并保存其数组下标
13             if(a[j]<a[minIndex])
14             {
15                 minIndex=j;
16             }
17         }
18         if(minIndex!=i)
19         {
20             //如果不是无序区的最小值位置不是默认的第一个数据，则交换之。
21             temp=a[i];
22             a[i]=a[minIndex];
23             a[minIndex]=temp;
24         }
25     }
26 }

4.P306 Exercise9.7

 1 import java.util.Date;
 2 
 3 public class Account {
 4     private int id;
 5     private double balance;
 6     private static double aIR;
 7     private Date date=new Date();
 8     public Account(){
 9         
10     }
11     public Account(int id,double balance){
12         this.id = id;
13         this.balance = balance;
14     }
15     public int getId()
16         {return id;}
17     public double getBalance()
18         {return balance;}
19     public double getAIR()
20         {return aIR;}
21     public void setId(int i)
22         {id=i;}
23     public void setBalance(double b)
24         {balance=b;}
25     public void setaIR(double k)
26         {aIR=k;}
27     public String getdate()
28         {return date.toString();}
29     public double getMIR()
30         {return aIR/12;}
31     public void withdraw(double wd){
32         balance-=wd;
33     }
34     public void deposit(double d ){
35         balance-=d;
36     }
37     
38     public static void main(String[] args) {
39         // TODO Auto-generated method stub
40     Account a = new Account(24, 15000);
41     a.setaIR(0.15);
42     System.out.println("the id of the acount is "+a.getId()+"
"+"the balance is "+a.getBalance()
43     +"
"+"the aIR is "+a.getAIR()+"
theMTR is "+a.getMIR()+"
the date is "+a.getdate());
44     System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
45     a.withdraw(7500);
46     System.out.println("the id of the acount is "+a.getId()+"
"+"the balance is "+a.getBalance()
47     +"
"+"the aIR is "+a.getAIR()+"
theMTR is "+a.getMIR()+"
the date is "+a.getdate());
48     }
49     
50 
51 }