import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
public class FileOperationExample {
public static void main(String[] args) {
try {
File file = new File("example.txt");
FileWriter writer = new FileWriter(file);
writer.write("Hello, world!");
writer.close();
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
System.out.println(line);
}
scanner.close();
file.delete();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class ServerExample {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(1234);
while (true) {
Socket socket = serverSocket.accept();
Thread thread = new RequestHandler(socket);
thread.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
class RequestHandler extends Thread {
private Socket socket;
public RequestHandler(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
// ...
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.io.IOException;
import java.net.Socket;
public class ClientExample {
public static void main(String[] args) {
try {
Socket socket = new Socket("localhost", 1234);
// ...
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DatabaseExample {
public static void main(String[] args) {
try {
Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/example", "root", "password");
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SELECT * FROM users");
while (resultSet.next()) {
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
System.out.println("ID: " + id + ", Name: " + name);
}
resultSet.close();
statement.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
