java_作业.doc

/我的第一个java programmpublic class J_hellopublic static void main(String args )System.out.println(*);System.out.println(* Practice makes perfect);System.out.println(*);/我的第一个java programmimport java.awt.Graphics;import javax.swing.JApplet;public class J_helloApplet extends JAppletpublic void paint(Graphics g)g.clearRect(0, 0, getWidth(),getHeight();g.drawString(*,10,20);g.drawString(* 孰能生巧,10,40);g.drawString(*,10,50); 第一个java小应用程序 /* 输出菱形星号*/public class control1 public static void main(String arg )int row = 4;int i = 0,j = 0,k = 0;for (i = 1; i row+1;i+)for (j = 0; j row-i ; j+)System.out.print( );for (k = 0; k 0;i-)for (j = 0; j row-i ; j+)System.out.print( );for (k = 0; k 2*i-2;k+)System.out.print(*);System.out.println(*);/*输出菱形星号和一个加号*/public class control2 public static void main(String arg )int row = 4; int i = 0,j = 0,k = 0;for (i = 1; i row;i+)for (j = 0; j row-i ; j+)System.out.print( );for (k = 0; k 2*i-2;k+)System.out.print(*);System.out.println(*);for (k = 0; k 0;i-)for (j = 0; j row-i ; j+)System.out.print( );for (k = 0; k 2*i-2;k+)System.out.print(*);System.out.println(*);/利用random 计算习题public class calculate public static void main(String args) int i,temp; int counter = new int21;for (i = 1; i = 10000; i+)temp = (int)(Math.random()*20 + 0.5);countertemp+;for (i = 0; i 21; i+)System.out.println(生成+i+的个数为:+counteri);/2008年日历生成import java.util.*;public class calendar public static void main(String arg)int imonth,iday,maxDay,temp,i;int Year = 2008;String str = 日,一,二,三,四,五,六;GregorianCalendar da = new GregorianCalendar();for (imonth = 0; imonth 12; imonth+)/控制月份变化System.out.println(*+2008年+(imonth+1)+月份*);da.set(Year, imonth, 0);for (i = 0; i 7; i+)System.out.printf(%s,stri);System.out.printf( );System.out.println();maxDay = da.getActualMaximum(Calendar.DAY_OF_MONTH);temp = da.get(Calendar.DAY_OF_WEEK);for (i = 0; i temp%7; i+) /对每个月的第一天进行处理，起始位置System.out.printf( );for (iday = 0; iday maxDay; iday+)/控制年变化da.set(Year,imonth,iday);System.out.printf(%-2d,iday+1);System.out.printf( );if (6 = da.get(Calendar.DAY_OF_WEEK)System.out.printf(n);System.out.println();System.out.println(*);/奥运趣味题目import java.util.Arrays;public class olmpic public static void main(String args) / TODO Auto-generated method stubint num = new int5; int sum = new int5;int all = new int10; int standar = 0,1,2,3,4,5,6,7,8,9; int data = 0,temp;for (data = 0; data 100000-20085; data+)split(data,num);temp = data + 20085;split(temp,sum);for (int i = 0; i 5; i+)alli = numi; all9-i = sumi;Arrays.sort(all);if (Arrays.equals(all, standar)System.out.println(data+符合要求);public static void split(int a, int b)for (int i = 0; i 5; i+)bi = a%10; a -= bi; a /= 10;/* 文件章节第一题*/import java.io.IOException;import java.io.*;import java.util.Arrays;public class score1 public static void main(String args) try BufferedReader inb = new BufferedReader(new InputStreamReader(System.in);RandomAccessFile f = new RandomAccessFile(data.txt,rw);int score = new int5;int i;int sum = 0;double ave;for (i = 0; i 5; i+)String str = inb.readLine();scorei = Integer.parseInt(str);f.writeInt(scorei); /写入文件sum += scorei;ave = sum*1.0/5;Arrays.sort(score);System.out.print(学生成绩按从小到大为：);for (i = 0; i 5; i+)System.out.print( +scorei);System.out.println(学生的平均成绩是:+ave);inb.close();f.close();catch (IOException e)System.err.print(e);/*文件章节第二题*/import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.RandomAccessFile;public class score2 public static void main(String args) try BufferedReader inb = new BufferedReader(new InputStreamReader(System.in);RandomAccessFile f = new RandomAccessFile(data.txt,rw);int temp,i;int score = new int5;double ave;f.seek(0);temp = 0;for (i = 0; i 5; i+)scorei = f.readInt();temp += scorei;ave = temp*1.0/5;/计算平均值f.seek(0);for (i = 0; i 5; i+)if (i != 2)f.writeDouble(scorei);elsef.writeDouble(ave);f.seek(0);System.out.print(修改后的学生成绩分别为：);for (i = 0; i 5; i+)System.out.print( +f.readDouble();inb.close();f.close();catch (IOException e)System.err.print(e);/判断是否是素数import java.util.Scanner;public class isPrime public static void main(String arg )int num,i,tag = 1;Scanner input = new Scanner(System.in);while (true)System.out.println(请输入要判断的数字,输入以-1结束:);num = input.nextInt();if (num = -1)return;if (num = 1)System.out.println(num+不是素数！);tag = 0;for (i = 2; i 0)c = Math.sqrt(det);System.out.println(方程有两个不同的实根:+(-1*b+c)/(2*a)+;+(-1*b-c)/(2*a);elsec = Math.sqrt(-1*det)/(2*a);b = (-1*b)/(2*a);System.out.println(方程有两个不同的虚根:+b+c+i+;+b+-+c+i);import .*;import java.io.*;public class clientsocket public static void main(String args) throws IOException InetAddress addr = InetAddress.getByName(null);System.out.println(addr = + addr);Socket socket = new Socket(addr, servesocket.PORT);try System.out.println(socket = + socket);BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream();PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream(), true);for (int i = 0; i 10; i+) out.println(www + i);String str = in.readLine();System.out.println(str);out.println(END); finally System.out.println(closing.);socket.close();import java.io.*; import .*; public class net public static void main(String args) tryURL url = new URL();InputStreamReader isr = new InputStreamReader(url.openStream();BufferedReader br = new BufferedReader(isr);String s;while (s=br.readLine()!=null)System.out.println(s);br.close();catch (Exception e)System.err.print(有异常);e.printStackTrace();import java.io.*;import .*;public class servesocket public static final int PORT = 9999;pu