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

import java.util.Date;
import java.util.Random;

public class StopWatch {
    private double starttime ;
    private double endtime ;
    public StopWatch() {
        starttime =System.currentTimeMillis();
    }
    public void start(){
        starttime =System.currentTimeMillis();
    }
    public void stop(){
        endtime = System.currentTimeMillis();
    }
    public double gettime(){
        return endtime-starttime;
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
    int[] a  = new int[1000];
    Random t = new Random();
    StopWatch sw = new StopWatch();
    sw.start();
    for(int k:a)
    {k=t.nextInt(10000);}
    int index=0;
    for(int b=0;b<a.length-1;b++)
    {
        int ret=a[b];
        for(int c=b+1;c<a.length;c++)
        {
            if(a[c]<ret)
                index=c;
                ret =a[c];
        }
        if(ret!=a[b])
        {int temp = a[b];
        a[b] = a[index];
        a[index] = temp;}
    }
    sw.stop();
    System.out.println(sw.gettime());
    }
    
}

注意选择排序的写法。要熟练。

3选择排序，非常简答的程序

public static void selectSort(int[]a)
{
    int minIndex=0;
    int temp=0;
    if((a==null)||(a.length==0))
        return;
    for(int i=0;i<a.length-1;i++)
    {
        minIndex=i;//无序区的最小数据数组下标
        for(intj=i+1;j<a.length;j++)
        {
            //在无序区中找到最小数据并保存其数组下标
            if(a[j]<a[minIndex])
            {
                minIndex=j;
            }
        }
        if(minIndex!=i)
        {
            //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。
            temp=a[i];
            a[i]=a[minIndex];
            a[minIndex]=temp;
        }
    }
}

4.P306 Exercise9.7

import java.util.Date;

public class Account {
    private int id;
    private double balance;
    private static double aIR;
    private Date date=new Date();
    public Account(){
        
    }
    public Account(int id,double balance){
        this.id = id;
        this.balance = balance;
    }
    public int getId()
        {return id;}
    public double getBalance()
        {return balance;}
    public double getAIR()
        {return aIR;}
    public void setId(int i)
        {id=i;}
    public void setBalance(double b)
        {balance=b;}
    public void setaIR(double k)
        {aIR=k;}
    public String getdate()
        {return date.toString();}
    public double getMIR()
        {return aIR/12;}
    public void withdraw(double wd){
        balance-=wd;
    }
    public void deposit(double d ){
        balance-=d;
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
    Account a = new Account(24, 15000);
    a.setaIR(0.15);
    System.out.println("the id of the acount is "+a.getId()+"
"+"the balance is "+a.getBalance()
    +"
"+"the aIR is "+a.getAIR()+"
theMTR is "+a.getMIR()+"
the date is "+a.getdate());
    System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    a.withdraw(7500);
    System.out.println("the id of the acount is "+a.getId()+"
"+"the balance is "+a.getBalance()
    +"
"+"the aIR is "+a.getAIR()+"
theMTR is "+a.getMIR()+"
the date is "+a.getdate());
    }
    

}