Java面試系列17-程式設計題-讀取伺服器字元、實現序列化、計數器、1000階乘、n出列問題等

阿新 • • 發佈：2022-05-04

一，Java的通訊程式設計，程式設計題(或問答)，用JAVA SOCKET程式設計，讀伺服器幾個字元，再寫入本地顯示？

Server端程式：

package test;
import java.net.*;
import java.io.*; public class Server{
  private ServerSocket ss;
  private Socket socket;
  private BufferedReader in;
  private PrintWriter out;
 public Server() {
  try {
   ss=new ServerSocket(10000);
   while(true) {
    socket = ss.accept();
    String RemoteIP = socket.getInetAddress().getHostAddress();
    String RemotePort = ":"+socket.getLocalPort();
    System.out.println("A client come in!IP:"+RemoteIP+RemotePort);
    in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    String line = in.readLine();
    System.out.println("Cleint send is :" + line);
    out = new PrintWriter(socket.getOutputStream(),true);
    out.println("Your Message Received!");
    out.close();
    in.close();
    socket.close();
   }
  }catch (IOException e) {
   out.println("wrong");
  }
 }  public static void main(String[] args) {
  new Server();
 }
}

Client端程式：

package test;
import java.io.*;
import java.net.*; public class Client {
 Socket socket;
 BufferedReader in;
 PrintWriter out;
 public Client() {
  try {
   System.out.println("Try to Connect to 127.0.0.1:10000");
   socket = new Socket("127.0.0.1",10000);
   System.out.println("The Server Connected!");
   System.out.println("Please enter some Character:");
   BufferedReader line = new BufferedReader(new InputStreamReader(System.in));
   out = new PrintWriter(socket.getOutputStream(),true);
   out.println(line.readLine());
   in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
   System.out.println(in.readLine());
   out.close();
   in.close();
   socket.close();
  }catch(IOException e) {
   out.println("Wrong");
  }
 }  public static void main(String[] args) {
  new Client();
 }
}

二、用JAVA實現一種排序，JAVA類實現序列化的方法(二種)？如在COLLECTION框架中，實現比較要實現什麼樣的介面？

用插入法進行排序程式碼如下：

package test;
import java.util.*;
class  InsertSort {
 ArrayList al;  public InsertSort(int num,int mod) {
  al = new ArrayList(num);
  Random rand = new Random();
  System.out.println("The ArrayList Sort Before:");
  for (int i=0;i<num ;i++) {
   al.add(new Integer(Math.abs(rand.nextInt()) % mod + 1));
   System.out.println("al["+i+"]="+al.get(i));
  }
 }  public void SortIt() {
  Integer tempInt;
  int MaxSize=1;
  for(int i=1;i<al.size();i++) {
   tempInt = (Integer)al.remove(i);
   if(tempInt.intValue()>=((Integer)al.get(MaxSize-1)).intValue()) {
    al.add(MaxSize,tempInt);
    MaxSize++;
    System.out.println(al.toString());
   } else {
    for (int j=0;j<MaxSize ;j++ ) {
     if (((Integer)al.get(j)).intValue()>=tempInt.intValue()) {
      al.add(j,tempInt);
      MaxSize++;
      System.out.println(al.toString());
      break;
     }
    }
   }
  }   System.out.println("The ArrayList Sort After:");
  for(int i=0;i<al.size();i++) {
   System.out.println("al["+i+"]="+al.get(i));
  }
 }  public static void main(String[] args) {
  InsertSort is = new InsertSort(10,100);
  is.SortIt();
 }
}

三、檔案讀寫,實現一個計數器

public int getNum(){
        int i = -1;
        try{
            String stri="";
            BufferedReader in = new BufferedReader(new FileReader(f));
            while((stri=in.readLine())!=null){
                i = Integer.parseInt(stri.trim());
            }
            in.close();
        }catch(Exception e){
            e.printStackTrace();
        }
        return i;
    }
    public void setNum(){
        int i = getNum();
        i++;        
        try{
            PrintWriter out=new PrintWriter(new BufferedWriter(new 
FileWriter(f,false)));  
            out.write(String.valueOf(i));            
//可能是編碼的原因，如果直接寫入int的話，將出現java編碼和windows編碼的混亂，因此此處寫入的是String
            out.close() ;
        }catch(Exception e){
            e.printStackTrace();
        }
    }

四、程式設計題：設有ｎ個人依圍成一圈，從第１個人開始報數，數到第ｍ個人出列，然後從出列的下一個人開始報數，數到第ｍ個人又出列，…，如此反覆到所有的人全部出列為止。設ｎ個人的編號分別為1，2，…，n，打印出出列的順序；要求用java實現。(Core Java)

程式碼如下：

package test;
public class CountGame {
private static boolean same(int[] p,int l,int n){
for(int i=0;i<l;i++){
if(p[i]==n){
return true;
}
}
return false;
}
public static void play(int playerNum, int step){
int[] p=new int[playerNum];
int counter = 1;
while(true){
if(counter > playerNum*step){
break;
}
for(int i=1;i<playerNum+1;i++){
while(true){
if(same(p,playerNum,i)==false) break;
else i=i+1;
}
if(i > playerNum)break;
if(counter%step==0){
System.out.print(i + " ");
p[counter/step-1]=i;
}
counter+=1;
}
}
System.out.println();
}
public static void main(String[] args) {
play(10, 7);
}
}

五、寫一個方法1000的階乘。(C++)

（瞭解一下，變態公司會問C的問題）

C++的程式碼實現如下：

#include <iostream>
#include <iomanip>
#include <vector>
using namespace std;
class longint {
private:
vector<int> iv;
public:
longint(void) { iv.push_back(1); }
longint& multiply(const int &);
friend ostream& operator<<(ostream &, const longint &);
};
ostream& operator<<(ostream &os, const longint &v) {
vector<int>::const_reverse_iterator iv_iter = v.iv.rbegin();
os << *iv_iter++;
for ( ; iv_iter < v.iv.rend(); ++iv_iter) {
os << setfill('0') << setw(4) << *iv_iter;
}
return os;
}
longint& longint::multiply(const int &rv) {
vector<int>::iterator iv_iter = iv.begin();
int overflow = 0, product = 0;
for ( ; iv_iter < iv.end(); ++iv_iter) {
product = (*iv_iter) * rv;
product += overflow;
overflow = 0;
if (product > 10000) {
overflow = product / 10000;
product -= overflow * 10000;
}
*iv_iter = product;
}
if (0 != overflow) {
iv.push_back(overflow);
}
return *this;
}
　　int main(int argc, char **argv) {
　　longint result;
int l = 0;
　　if(argc==1){
　　cout << "like: multiply 1000" << endl;
exit(0);
　　}
　　sscanf(argv[1], "%d", &l);
　　for (int i = 2; i <= l; ++i) {
　　result.multiply(i);
　　}
　　cout << result << endl;
　　return 0;