các hàm xử lý chuổi trong java

CÁC DẠNG BÀI XỬ LÝ CHUỔI THEO TCP Đếm ký tự chuỗi không tính khoảng trắng//B2: Thuc hien lang nghe tu Socket server den socket client va ket noi tu Client Socket client = server.accept;

CÁC HÀM XỬ LÝ CHUỔI TRONG JAVA 1.Khai báo chuổi

+ Chuỗi rỗng :

String str1=new String( ); //khởi tạo str1 là một xâu trống

+ Bằng một chuỗi cho trước

String str2=new String(“”Hello word”“); //khởitạo str2 bằng “Hello word

+ Bằng một mảng kí tự cho trước

char ch[ ]={a,b,c,d,e};

String str3=new String[ch];

+ Bằng cách chọn một vài kí tự trong một mảng kí tự cho trước

char ch[ ]={“a“,“b“,“c“,“d“,“e“};

String str4=new String[ch,0,2];

Kết quả str4 là xâu “”ab” , vì khởi tạo này sẽ khởi tạo xâu str4 là lấy 2 kí tự từ vị trí thứ 0

2.Kiểm trả chuỗi bắt đầu của chuỗi

String str1=new String(“Hello word”“);

System.out.printf(“I want to say:”“+str1);

String str1=new String(“hoc.itop.vn”);

8 Trả về kí tự thứ 0 tính từ vị trí thư k trong xâu str1

String str1=new String(”itop.vn”);

char ch=str1.charAt(k);

9 So sánh 2 chuỗi

String str1=new String(“hello”);

String str2=new String(“ITOP”);

vídụ: String str1=new String(“kc”);

String str2=new String(“kavcb”);

12 Trả về vị trí của chuỗi str2 và str3 trong chuỗi str1.nếu không tìm thấy sẽ trả về giá trị -1

String str1=new String(“hoc.itop.vn”);

String str2=new String(“op”);

String str3=new String(“ab”);

18 Chuyển kiểu dữ liệu từ String sang số

 Vídụ: String str1=new String(“”124”“);

int n=Integer.parseInt(str1);

kế tquả là n=124

TCP

3

CÁC DẠNG BÀI XỬ LÝ CHUỔI THEO TCP Đếm ký tự chuỗi không tính khoảng trắng

//B2: Thuc hien lang nghe (tu Socket server den socket client) va ket noi tu Client

Socket client = server.accept();

//Thong bao lay ket noi thanh congSystem.out.println("Ket noi thanh cong");

//B3: Nhan du lieu tu may Client ve Server//B3.1: khai bao doi tuong

BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));

// getInputStream(): doc tu dong vao ra va luu vao bien br

//gui du lieu tu Server den ClientPrintWriter pw = new PrintWriter(client.getOutputStream());

//DataOutputStream dos = new DataOutputStream(client.getOutputStream());

//B3.2 : Doc du lieu vao st, Server nhan chuoi tu clientString st = br.readLine();//readLine() : lay du lieu xuong//B4 : Server xu ly chuoi

System.out.println("Dong ket noi");

}public static int demtu(String st){

//B1: khai bao Socket server voi may ao cuc bo "127.0.0.1"

Socket client = new Socket("127.0.0.1",8081);

//B2: Nhan du lieu tu ban phim, khai bao doi tuong

// in: doc du lieu tu ban phim nhap vao tren System.in// br: doc du lieu tren Socket client do Server goi qua// pw : ghi du lieu cao Socket client goi cho ServerBufferedReader in = new BufferedReader(new InputStreamReader(System.in));

//Nhan du lieu tu may ServerBufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));

//

PrintWriter pw = new PrintWriter(client.getOutputStream());

//

System.out.println("Nhap chuoi can gui:");

//B3 : nhap chuoi tu ban phimString st = in.readLine();

//B1: Khai bao Socket server voi cong la 9999ServerSocket server = new ServerSocket(9999);

// Thong bao cho ket noiSystem.out.println("Server dang cho ket noi tu Client");

//B2: Thuc hien lang nghe va ket noi tu ClientSocket client = server.accept();

//Thong bao lay ket noi thanh congSystem.out.println("Ket noi thanh cong");

//B3: Nhan du lieu tu may Client ve ServerBufferedReader brIn = new BufferedReader(new InputStreamReader(client.getInputStream()));

//gui du lieu tu Server den ClientDataOutputStream dos = new DataOutputStream(client.getOutputStream());

//Doc du lieu vao stString st = brIn.readLine();

//thong bao chuoi hien thiSystem.out.println("Da nhan duoc chuoi");

//xuat du lieu ra man hinhSystem.out.println(st);

//doi chuoi thanh chu hoa

st = st.toUpperCase();

//B5: gui du lieu didos.writeBytes(st);

//B1: khai bao Socket server voi may ao cuc bo "127.0.0.1"

Socket client = new Socket("127.0.0.1",9999);

//B2: Nhan du lieu tu ban phimBufferedReader br = new BufferedReader(new InputStreamReader(System.in));

//Nhan du lieu tu may ServerBufferedReader brIn = new BufferedReader(new InputStreamReader(client.getInputStream()));

DataOutputStream dos = new DataOutputStream(client.getOutputStream());

System.out.println("Nhap chuoi can gui:");

System.out.println("Xu ly doi thanh chu hoa tu Server:");

System.out.println(st);

client.close();

}catch(UnknownHostException e){

//B2: Thuc hien lang nghe (tu Socket server den socket client) va ket noi tu Client

Socket client = server.accept();

//Thong bao lay ket noi thanh congSystem.out.println("Ket noi thanh cong");

//B3: Nhan du lieu tu may Client ve Server//B3.1: khai bao doi tuong

BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));

// getInputStream(): doc tu dong vao ra va luu vao bien br

//gui du lieu tu Server den ClientPrintWriter pw = new PrintWriter(client.getOutputStream());

//B3.2 : Doc du lieu vao st, Server nhan chuoi tu clientString st = br.readLine();//readLine() : lay du lieu xuong//B4 : Server xu ly chuoi

String kq = daonguoc(st);

//B5: Server tra lai clientpw.write(kq);

pw.write("\n");

StringBuffer in = new StringBuffer(st).reverse();// reverse(): phuong thuc dao nguoc bo nho

String nguoc = in.toString();// toString(): pthuc tra dia chi ve kieu chuoireturn nguoc;

//B1: khai bao Socket server voi may ao cuc bo "127.0.0.1"

Socket client = new Socket("127.0.0.1",8080);

//B2: Nhan du lieu tu ban phim, khai bao doi tuong

// in: doc du lieu tu ban phim nhap vao tren System.in// br: doc du lieu tren Socket client do Server goi qua// pw : ghi du lieu cao Socket client goi cho ServerBufferedReader in = new BufferedReader(new InputStreamReader(System.in));

//Nhan du lieu tu may ServerBufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));

PrintWriter pw = new PrintWriter(client.getOutputStream());

System.out.println("Nhap chuoi can gui:");

//B3 : nhap chuoi tu ban phimString st = in.readLine();

pw.write(st);

pw.write("\n");

pw.flush();

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public static void main(String args[]) {

System.out.print("May chu da ket noi tu client!\n");

Socket conectionSocket = ss.accept();

BufferedReader fromClient = new BufferedReader(new InputStreamReader(conectionSocket.getInputStream()));

DataOutputStream sendToClient = new DataOutputStream(conectionSocket.getOutputStream());

while (true){

cau = fromClient.readLine();

System.out.println("Chuoi tu client goi den:"+cau);

//dao chuoiStringBuilder str= new StringBuilder(cau);

ketQua = str.reverse().toString();

sendToClient.writeBytes(ketQua + '\n');

catch(Exception e){

BufferedReader inFormUser = new BufferedReader (new InputStreamReader(System.in));

Socket clientSocket = new Socket ("127.0.0.1", 9999);

DataOutputStream sendToServer = new DataOutputStream(clientSocket.getOutputStream());

BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

System.out.println("Nhap vao chuoi:");

catch (Exception e){

System.out.print("He thong ko lam viec!\n");

public static ServerSocket servsock;

public static final int PORT = 1234;

public static void main(String[] args)

{

try{

servsock = new ServerSocket(PORT);

int localPort = servsock.getLocalPort();

System.out.println("\n Server dang mo port: " +localPort+".");

}catch(IOException ioEx){

System.out.println("\n Khong mo duoc port: " +PORT);

System.exit(1);

}do{

handleClient();

}while(true);

clientsock = servsock.accept();

String hostname = clientsock.getInetAddress().getHostAddress();

String destAdd = clientsock.getInetAddress().getHostAddress();

int destPort = clientsock.getPort();

System.out.println("Chap nhan ket noi tu "+hostname+"("+destAdd+") tai port"+destPort+".");

PrintWriter out = new PrintWriter(clientsock.getOutputStream(), true);

BufferedReader in = new BufferedReader(new InputStreamReader(clientsock.getInputStream()));

while (true){

String aStr = in.readLine();

System.out.println("\n Nhan tu client ("+hostname+") gia tri A = " +aStr);

a = Float.parseFloat(aStr);

b = Float.parseFloat(bStr);

c = Float.parseFloat(cStr);

}catch(NumberFormatException e){out.println("So khong hop le"); continue;}

if(a==0) if(b==0) if(c==0) kq="Phuong trinh vo so nghiem";

else kq="Phuong trinh vo nghiem";

else kq="Phuong trinh co nghiem x="+(-c/b);

else { double delta = b*b-4*a*c;

double x1 = (-b+Math.sqrt(delta))/(2*a);

double x2 = (-b-Math.sqrt(delta))/(2*a);

if(delta>0) kq = "Phuong trinh co 2 nghiem kep: x1=x2="+(-b/(2*a));

else kq="phuong trinh vo nghiem";

} System.out.println("Ket qua:" +kq);

out.println("ket qua tu server:" +kq);

System.out.println("\n Khong ngat duoc ket noi");

Socket clientsock = new Socket("127.0.0.1", 1234);

PrintWriter out = new PrintWriter(clientsock.getOutputStream(), true);

BufferedReader in = new BufferedReader(new InputStreamReader(clientsock.getInputStream()));

BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

System.out.print("\n Nhap vao he so A= ");

String aStr = stdIn.readLine();

import java.lang.*;//xu ly chuoi

import java.io.*;//xu ly vao ra

import java.net.*;//day la lap trinh socket nen co goi nay

ServerSocket srvr = new ServerSocket(1234);//tao socket cua server (gan lun port)

//System.out.println("may chu dang cho ket noi tu client");

Socket skt = srvr.accept();//lang nge va cho ket noi tu client

//System.out.println("May chu da duoc ket noi!\n");

PrintWriter out = new PrintWriter(skt.getOutputStream(), true); //ghi dulieu

Socket skt1 = new Socket("localhost", 1234); //gan dc IP va port

BufferedReader in = new BufferedReader(new

InputStreamReader(skt1.getInputStream()));

System.out.print("Server: ");

while (!in.ready()) {} //doc chuoi

System.out.println(in.readLine()); // Doc mot dong va in no ra man hinh

15

Socket skt = new Socket("localhost", 1234); //gan dc IP va port

BufferedReader in = new BufferedReader(new

InputStreamReader(skt.getInputStream()));

System.out.print("Server: ");

while (!in.ready()) {} //doc chuoi

System.out.println(in.readLine()); // Doc mot dong va in no ra man hinh

ServerSocket srvr = new ServerSocket(1234);//tao socket cua server (gan lun port)

//System.out.println("may chu dang cho ket noi tu client");

Socket skt1 = srvr.accept();//lang nge va cho ket noi tu client

//System.out.println("May chu da duoc ket noi!\n");

PrintWriter out = new PrintWriter(skt1.getOutputStream(), true); //ghi dulieu

* To change this template, choose Tools | Templates

* and open the template in the editor

*/

package kiemtrathuchanh;

import java.io.*;

import java.net.*;

public class Server_Fibo {

static ServerSocket server;

static Socket client;

public static void main (String arg[]){

try {

server = new ServerSocket(5000);

System.out.println("Server dang khoi dong ");

client= server.accept();

System.out.println("Server da dc ket noi");

BufferedReader brIn = new BufferedReader(new InputStreamReader(client.getInputStream()));

DataOutputStream dos = new DataOutputStream(client.getOutputStream());

//dos.write(13);// ma 13 : ky tu cuoi dong`

//dos.write(10);// ma 10 : ky tu dau dong`

//int i=Timvitri(st, 1);

int result = -1;

String[] arr = st.split(",");

for (int i = 0; i < arr.length; i++) {

if(Integer.parseInt(arr[i]) == a){

result=i;

}}

}

Client_Fibo.java

/*

* To change this template, choose Tools | Templates

* and open the template in the editor

*/

package kiemtrathuchanh;

import java.io.*;

import java.net.*;

public class Client_Fibo {

static String Timvitri(String string, int x)

{

String result = "";

String[] arr = string.split(",");

17

for (int i = 0; i < arr.length; i++) {

if(Integer.parseInt(arr[i]) == x){

result= String.valueOf(i);

return result;

}}

return "Ko tim thay so can tim";

}

public static void main(String arg[]){

try {

Socket client= new Socket("127.0.0.1",5000);

BufferedReader br= new BufferedReader(new InputStreamReader(System.in));

DataOutputStream dos= new DataOutputStream(client.getOutputStream());

BufferedReader brIn= new BufferedReader(new InputStreamReader(client.getInputStream()));

System.out.println("Nhap chuoi can gui ");

static String ViTri(String st)

if(Integer.parseInt(arr[i]) %2 != 0){

kq=kq+arr[i]+",";

i++;

}else

i++;

}return kq;

}

public static void main(String[] args)

{

try{

ServerSocket server = new ServerSocket(1234);

System.out.println("Server: Da khoi dong may chu\n");

Socket soc= server.accept();

System.out.println("May chu da duoc ket noi");

System.err.println("Khong lam viec");

System.exit(1);

}}

try{

Socket inComing=new Socket("localhost",1234);

System.out.println("Client: da ket noi may chu");

PrintWriter out=new PrintWriter(inComing.getOutputStream(), true );

Scanner in= new Scanner(inComing.getInputStream());

Scanner sc=new Scanner(System.in);

System.err.println("Khong tim thay may chu");

System.exit(1);

}catch(IOException e){

System.err.println("Khong the ket noi");

System.exit(1);

}}

public class server {

public static void main(String []args) throws IOException

{

//B1 : Ket Noi

ServerSocket server = new ServerSocket(8080);

Socket client = server.accept(); System.out.println("ket noi thanh cong");

//B2 : Khai bao doi tuong

BufferedReader br = new BufferedReader(new

InputStreamReader(client.getInputStream()));

PrintWriter pw = new PrintWriter(client.getOutputStream());

//B3 : Nhan Chuoi Tu Client

public class client {

public static void main(String []args) throws Exception

{

//B1 : ket noi

Socket server = new Socket("127.0.0.1",8080);

System.out.println("ket Noi thanh cong");

//B2 : Khai bao doi tuong

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

BufferedReader br = new BufferedReader(new InputStreamReader(server.getInputStream()));

PrintWriter pw = new PrintWriter(server.getOutputStream());

//int kq = Integer.parseInt(br.readLine());

String kq = br.readLine();

//B6 : In ket qua ra man hinh

System.out.println("Chuyen Chu Cai Dau Thanh Chu Hoa : " + kq);

public class server {

public static void main(String []args) throws IOException

{

//B1 : Ket Noi

ServerSocket server = new ServerSocket(8080);

Socket client = server.accept(); System.out.println("ket noi thanh cong");

//B2 : Khai bao doi tuong

BufferedReader br = new BufferedReader(new

InputStreamReader(client.getInputStream()));

PrintWriter pw = new PrintWriter(client.getOutputStream());

//B3 : Nhan Chuoi Tu Client

char kt='A'; //Ky Tu Muon Dem

for (int i=0;i<st.length();i++)

import java.io.*;

import java.net.*;

public class client {

public static void main(String []args) throws Exception

{

//B1 : ket noi

Socket server = new Socket("127.0.0.1",8080);

System.out.println("ket Noi thanh cong");

//B2 : Khai bao doi tuong

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

BufferedReader br = new BufferedReader(new InputStreamReader(server.getInputStream()));

PrintWriter pw = new PrintWriter(server.getOutputStream());

//B6 : In ket qua ra man hinh

System.out.println("So Lan Xuat Hien Cua 1 Ky Tu Trong Chuoi : " +kq);

}

}

CẮT KÝ TỰ TRỐNG MỘT CHUỖI SERVER:

import java.io.*;

import java.net.*;

public class server {

public static void main(String [] args) throws IOException

{

//B1 : ket noi

ServerSocket server = new ServerSocket(12);

Socket client = server.accept();

//B2 : khai bao doi tuong

BufferedReader br = new BufferedReader(new

InputStreamReader(client.getInputStream()));

PrintWriter pw = new PrintWriter(client.getOutputStream());

//B3 : Nhan Chuoi Tu Client

public class client{

public static void main(String [] args) throws IOException

PrintWriter pw = new PrintWriter(server.getOutputStream());

//B3 : Nhap Chuoi Tu Ban Phim

//B6 : In ket qua ra man hinh

System.out.println("Chuoi Sau Khi Cat La: " + st);