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import myjava.PlotOtau和import myjava.*的区别？

Allen — Fri, 13 Jan 2006 15:10:00 GMT

import myjava.*；
import myjava.PlotOtau；
真不知道打*号为什么找不到路径？即使package myjava里就一个PlotOtau.class。

Allen 2006-01-13 23:10 发表评论

ClassDemo

Allen — Mon, 09 Jan 2006 12:50:00 GMT

1public class ClassDemo
2{
3    public ClassDemo(){}
4
5    public static void main(String[] args)
6    {
7        ClassDemo test=new ClassDemo();
8        System.out.println("The class of test is:"+test.getClass().getName());
9        try{
10            Class c=Class.forName("java.lang.Object");
11            System.out.println(c.getPackage()+"\t");
12            System.out.println(c);
13            java.lang.reflect.Method[] m=c.getMethods();
14            System.out.println("The element in String[] is:"+String[].class.getComponentType());
15            System.out.println((new int[3][4][5][6]).getClass().getName());
16            System.out.println("The method defined in Object class:");
17            for(int i=0; i<m.length; i++)
18            {
19                System.out.println(m[i]);
20            }
21           }
22        catch(ClassNotFoundException e)
23        {
24            e.printStackTrace();
25        }
26    }
27}

Allen 2006-01-09 20:50 发表评论

ComplexNumber

Allen — Mon, 09 Jan 2006 12:22:00 GMT

1public class ComplexNumber
2{
3        private double x,y;
4
5        public ComplexNumber(double real,double imaginary)
6        {
7                this.x=real;
8                this.y=imaginary;
9        }
10
11        public double real()
12        {
13            return x;
14        }
15
16        public double imaginary()
17        {
18            return y;
19        }
20
21        public double magnitude()
22        {
23            return Math.sqrt(x*x+y*y);
24        }
25
26        public String toString()
27        {
28            return "{"+x+","+y+"}";
29        }
30
31        public static ComplexNumber add(ComplexNumber a,ComplexNumber b)
32        {
33                return new ComplexNumber(a.x+b.x,a.y+b.y);
34        }
35
36        public ComplexNumber add(ComplexNumber a)
37        {
38                return new ComplexNumber(this.x+a.x,this.y+a.y);
39        }
40
41        public static ComplexNumber multiply(ComplexNumber a,ComplexNumber b)
42        {
43                return new ComplexNumber(a.x*b.x-a.y*b.y,a.x*b.y+a.y*b.x);
44        }
45
46        public ComplexNumber multiply(ComplexNumber a)
47        {
48                return new ComplexNumber(x*a.x-y*a.y,x*a.y+y*a.x);
49        }
50}

Allen 2006-01-09 20:22 发表评论

ArrayPrint

Allen — Mon, 09 Jan 2006 10:04:00 GMT

1import java.io.*;
2public class ArrayPrint
3{
4    private int N;
5    private int[][] intarray;
6    ArrayPrint()
7    {
8        N=5;
9        intarray=new int[N][N];
10    }
11    ArrayPrint(int n)
12    {
13        N=n;
14        intarray=new int[N][N];
15    }
16    public void Print()
17    {
18        int i=0,j=0;
19        int i0=0,j0=0;
20        int count=1;
21        int Num=N-1;
22        while(Num>0)
23        {
24            for(i=i0,j=j0;j<Num;j++,count++)
25            {
26                intarray[i][j]=count;
27            }
28            for(i=i0;i<Num;i++,count++)
29            {
30                intarray[i][j]=count;
31            }
32            for(j=Num;j>j0;j--,count++)
33            {
34                intarray[i][j]=count;
35            }
36            for(i=Num;i>i0;i--,count++)
37            {
38                intarray[i][j]=count;
39            }
40            i0++;
41            j0++;
42            Num--;
43        }
44        if(N%2!=0)
45        {
46            intarray[N/2][N/2]=count;
47        }
48        for(i=0;i<N;i++)
49        {
50            for(j=0;j<N;j++)
51            {
52                String ar="0";
53                if(intarray[i][j]/10<1)
54                {
55                    ar="  "+intarray[i][j];
56                }
57                else if(intarray[i][j]/100<1 && intarray[i][j]/10>=1)
58                {
59                    ar=" "+intarray[i][j];
60                }
61                System.out.print(ar+" ");
62            }
63            System.out.println();
64        }
65    }
66    public static void main(String[] args) throws IOException
67    {
68        int order=0;
69        System.out.println("Please input the order of the square:(<10:)");
70        order=System.in.read();
71        order=order-'0';
72        ArrayPrint arr=new ArrayPrint(order);
73        arr.Print();
74    }
75}

Allen 2006-01-09 18:04 发表评论

StringBufferDemo

Allen — Mon, 09 Jan 2006 05:27:00 GMT

1public class StringBufferDemo
2{
3 public static void main(String[] args)
4 {
5  StringBuffer sb=new StringBuffer("Java");
6  double d=1.4;
7  sb.append(d).append("have").append(new String(" a lot of new features"));
8  System.out.println(sb);
9  sb.insert(4,"SDK");
10  System.out.println(sb);
11  sb.delete(4,10);
12  System.out.println(sb);
13  System.out.println(sb.reverse());
14 }
15}

Allen 2006-01-09 13:27 发表评论

StringDemo

Allen — Mon, 09 Jan 2006 04:57:00 GMT

1public class StringDemo
2{
3 public static void main(String[] args)
4 {
5  String myName="G. Leeman";
6  int length="涂静静".length();
7  System.out.println("长度1："+myName.length());
8  System.out.println("长度2："+length);
9  String name1="programming in java";
10  String name2="Programming in Java";
11  System.out.println("比较1："+name1.equals(name2));
12  System.out.println("比较2："+name2.equalsIgnoreCase(name2));
13  System.out.println("比较3："+name2.compareTo("Progam"));
14  System.out.println("字符1："+name1.charAt(4));
15  System.out.println("字符2："+name1.indexOf('a'));
16  System.out.println("字符3："+name2.lastIndexOf('a'));
17  String subname="in";
18  System.out.println("子串1："+name1.substring(3,10));
19  System.out.println("子串2："+"abc".concat("123"));
20  System.out.println("子串3："+name2.startsWith("Pro"));
21  System.out.println("子串4："+name2.endsWith("in Java"));
22  System.out.println("子串5："+name1.indexOf(subname));
23  System.out.println("子串6："+name1.lastIndexOf(subname));
24  System.out.println("小写："+name2.toLowerCase());
25  System.out.println("大写："+name2.toUpperCase());
26  System.out.println("替换："+name1.replace('a','A'));
27 }
28}

Allen 2006-01-09 12:57 发表评论

CharacterDemo

Allen — Sat, 07 Jan 2006 09:59:00 GMT

1public class CharacterDemo
2{
3 public CharacterDemo()
4 {
5 }
6
7 public static void main(String[] args)
8 {
9  Character c1=new Character('A');
10  Character c2=new Character('b');
11  System.out.println(c1.charValue()+0);
12  System.out.println(c2.charValue()+0);
13  int i=c1.compareTo(c2);
14  System.out.println(i);
15  if(i==0)
16  {
17   System.out.println("c1 is equal c2!");
18  }
19  else if(i<0)
20  {
21   System.out.println("c1 is smaller than c2!");
22  }
23  System.out.println(Character.toLowerCase('A')+""+Character.toUpperCase('a'));
24  System.out.println(Character.isDigit('9'));
25 }
26}

Allen 2006-01-07 17:59 发表评论

CalendarDemo

Allen — Sat, 07 Jan 2006 09:58:00 GMT

1import java.util.*;
2
3public class CalendarDemo
4{
5 public static void main(String[] args)
6 {
7  Calendar instcalendar=Calendar.getInstance();
8
9         instcalendar.setTime(new Date());
10
11         String cyear=String.valueOf(instcalendar.get(Calendar.YEAR));
12         String cmonth=String.valueOf(instcalendar.get(Calendar.MONTH)+1);
13         String cdate=String.valueOf(instcalendar.get(Calendar.DAY_OF_MONTH));
14         String cday=String.valueOf(instcalendar.get(Calendar.DAY_OF_WEEK)-1);
15
16         int chour=instcalendar.get(Calendar.HOUR_OF_DAY);
17         int cminute=instcalendar.get(Calendar.MINUTE);
18         int csecond=instcalendar.get(Calendar.SECOND);
19
20         System.out.println("现在的时间是：");
21         System.out.println(""+cyear+"年"+cmonth+"月"+cdate+"日"+"星期"+cday);
22         System.out.println(""+chour+"时"+cminute+"分"+csecond+"秒");
23
24         instcalendar.set(2004,9,1);
25         long ctime2004=instcalendar.getTimeInMillis();
26         instcalendar.set(2005,9,1);
27         long ctime2005=instcalendar.getTimeInMillis();
28         long interdays=(ctime2005-ctime2004)/(1000*60*60*24);
29
30         System.out.println("2004年10月1日和2005年10月1日相隔"+interdays+"天");
31 }
32}
33

Allen 2006-01-07 17:58 发表评论

DayShower

Allen — Sat, 07 Jan 2006 09:56:00 GMT

1class DayShower
2{
3    public static void main(String[] args)
4    {
5        int yearIn=2004;
6        int monthIn=2;
7        if(args.length>0)
8        {
9            monthIn=Integer.parseInt(args[0]);
10        }
11        if(args.length>1)
12        {
13            yearIn=Integer.parseInt(args[1]);
14        }
15        System.out.println(yearIn+"Äê"+monthIn+"ÔÂÓÐ"+countDays(monthIn,yearIn)+"Ìì");
16    }
17    static int countDays(int month,int year)
18    {
19        int count=-1;
20        switch(month)
21        {
22            case 1:
23            case 3:
24            case 5:
25            case 7:
26            case 8:
27            case 10:
28            case 12: count=21;break;
29            case 4:
30            case 6:
31            case 9:
32            case 11: count=30;break;
33            case 2:
34            if(year%4==0)
35            {
36                count=29;
37            }
38            else
39            {
40                count=28;
41            }
42            if((year%100==0)&(year%400!=0))
43            {
44                count=28;
45            }
46        }
47        return count;
48    }
49}

Allen 2006-01-07 17:56 发表评论

MathDemo

Allen — Sat, 07 Jan 2006 09:56:00 GMT

1public class MathDemo
2{
3 public static void main(String[] args)
4 {
5  System.out.println("abs(-5)="+Math.abs(-5));
6  System.out.println("max(2.72,3.14)="+Math.max(2.72,3.14));
7  System.out.println("min(256,286)="+Math.min(256,286));
8
9  System.out.println("round(3.8)="+Math.round(3.8));
10  System.out.println("round(-3.8)="+Math.round(-3.8));
11
12  System.out.println("sqrt(2)="+Math.sqrt(2));
13  System.out.println("pow(2,3)="+Math.pow(2,3));
14
15  System.out.println("E="+Math.E);
16  System.out.println("exp(1)="+Math.exp(1));
17  System.out.println("log(e*e*e)="+Math.log((Math.E)*(Math.E)*(Math.E)));
18
19  System.out.println("ceil(3.14)="+(int)Math.ceil(3.14));
20  System.out.println("floor(3.14)="+(int)Math.floor(3.14));
21
22  System.out.println("pi="+Math.PI);
23  System.out.println("sin(pi/2)="+Math.sin(Math.PI/2));
24  System.out.println("cos(0)="+Math.cos(0));
25 }
26}

Allen 2006-01-07 17:56 发表评论

MaxVariables

Allen — Sat, 07 Jan 2006 09:55:00 GMT

1public class MaxVariables
2{
3  public static void main(String[] args)
4  {
5    byte largestByte=Byte.MAX_VALUE;
6    short largestShort=Short.MAX_VALUE;
7    int largestInteger=Integer.MAX_VALUE;
8    long largestLong=Long.MAX_VALUE;
9    float largestFloat=Float.MAX_VALUE;
10    double largestDouble=Double.MAX_VALUE;
11    char aChar='S';
12    boolean aBoolean=true;
13
14    System.out.println("最大的byte值是："+largestByte);
15    System.out.println("最大的short值是："+largestShort);
16    System.out.println("最大的integer值是："+largestInteger);
17    System.out.println("最大的long值是："+largestLong);
18    System.out.println("最大的float值是："+largestFloat);
19    System.out.println("最大的doubble值是："+largestDouble);
20    if(Character.isUpperCase(aChar))
21    {
22      System.out.println("字符"+aChar+"是大写字母");
23    }
24    else
25    {
26      System.out.println("字符"+aChar+"是小写字母");
27    }
28    System.out.println("布尔型变量的值是"+aBoolean);
29  }
30}

Allen 2006-01-07 17:55 发表评论

Test_java

Allen — Sat, 07 Jan 2006 09:52:00 GMT

1public class Test_java
2{
3  public static void main(String[] args)
4  {
5    System.out.println("This is a Test'javapro!");
6  }
7}
8

Allen 2006-01-07 17:52 发表评论

IntegerDemo

Allen — Sat, 07 Jan 2006 09:44:00 GMT

1public class IntegerDemo
2{
3  public IntegerDemo(){}
4  public static void main(String[] agrs)
5  {
6    Integer[] Integerarray={new Integer(20),new Integer(40),new Integer("110")};
7    for(int i=0;i<Integerarray.length;i++)
8    {
9      System.out.print(Integer.toBinaryString(Integerarray[i].intValue())+"\t");
10      System.out.print(Integer.toHexString(Integerarray[i].intValue())+"\t");
11      System.out.print(Integer.toOctalString(Integerarray[i].intValue())+"\t");
12      System.out.print(Integerarray[i]+"\r\n");
13    }
14  }
15}

Allen 2006-01-07 17:44 发表评论