package examples;

import java.io.*;

import java.nio.*;

import java.nio.channels.*;

import java.nio.file.*;

import java.time.LocalDateTime;

import java.time.format.DateTimeFormatter;

import java.util.*;

import java.util.concurrent.*;

import java.util.stream.Collectors;

import java.nio.charset.StandardCharsets;

public class NIOExample1 {

public static void main(String[] args) {

try {

NIOExamples.extractPalindromes("input.txt", "palindromes.txt");

NIOExamples.maskPassword();

NIOExamples.interactiveChat();

NIOExamples.logUserInput("user_log.txt");

NIOExamples.multiThreadedChat();

NIOExamples.realTimeDataStreaming("data_log.txt");

} catch (IOException e) {

e.printStackTrace();

}

}

}

class NIOExamples {

/**

* 50) Extract Palindromes from a File (NIO-based version)

* Reads a file using FileChannel and ByteBuffer, extracts all palindrome words,

* and writes them to another file using FileChannel and ByteBuffer.

*/

public static void extractPalindromes(String inputFile, String outputFile) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ);

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.WRITE, StandardOpenOption.CREATE)) {

ByteBuffer buffer = ByteBuffer.allocate(1024);

StringBuilder content = new StringBuilder();

while (inChannel.read(buffer) > 0) {

buffer.flip();

content.append(StandardCharsets.UTF_8.decode(buffer));

buffer.clear();

}

List<String> palindromes = Arrays.stream(content.toString().split("\\s+"))

.filter(word -> word.length() > 1 && word.equalsIgnoreCase(new StringBuilder(word).reverse().toString()))

.collect(Collectors.toList());

ByteBuffer outBuffer = ByteBuffer.wrap(String.join("\n", palindromes).getBytes(StandardCharsets.UTF_8));

outChannel.write(outBuffer);

}

}

/**

* 51) Password Masking on Console (NIO-based version)

* Reads a password from System.in via Channel-based NIO input stream,

* masks input, and securely stores it.

*/

public static void maskPassword() throws IOException {

System.out.print("Enter Password: ");

ReadableByteChannel inChannel = Channels.newChannel(System.in);

ByteBuffer buffer = ByteBuffer.allocate(50);

inChannel.read(buffer);

buffer.flip();

char[] passwordChars = new char[buffer.remaining()];

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

passwordChars[i] = (char) buffer.get();

System.out.print("*");

}

System.out.println("\nPassword securely stored.");

}

/**

* 52) Interactive Command-line Chat (NIO-based version)

* Simulates a chat where user inputs via non-blocking NIO and receives responses.

*/

public static void interactiveChat() throws IOException {

ReadableByteChannel inChannel = Channels.newChannel(System.in);

ByteBuffer buffer = ByteBuffer.allocate(256);

System.out.println("Start chatting (type 'exit' to quit):");

while (true) {

buffer.clear();

inChannel.read(buffer);

buffer.flip();

String input = StandardCharsets.UTF_8.decode(buffer).toString().trim();

if ("exit".equalsIgnoreCase(input)) break;

System.out.println("Bot: " + input.toUpperCase()); // Simple response logic

}

}

/**

* 53) Logging User Input to a File (NIO-based version)

* Captures user input using NIO Channels and logs them with timestamps.

*/

public static void logUserInput(String logFile) throws IOException {

FileChannel outChannel = FileChannel.open(Paths.get(logFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE, StandardOpenOption.APPEND);

ReadableByteChannel inChannel = Channels.newChannel(System.in);

ByteBuffer buffer = ByteBuffer.allocate(256);

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

System.out.println("Start typing (type 'exit' to quit):");

while (true) {

buffer.clear();

inChannel.read(buffer);

buffer.flip();

String input = StandardCharsets.UTF_8.decode(buffer).toString().trim();

if ("exit".equalsIgnoreCase(input)) break;

String logEntry = dtf.format(LocalDateTime.now()) + " - " + input + "\n";

ByteBuffer logBuffer = ByteBuffer.wrap(logEntry.getBytes(StandardCharsets.UTF_8));

outChannel.write(logBuffer);

}

}

/**

* 54) Multi-Threaded Console Chat (NIO-based version)

* Uses two threads: one for reading user input and another for responding asynchronously.

*/

public static void multiThreadedChat() {

ExecutorService executor = Executors.newFixedThreadPool(2);

executor.submit(() -> {

try {

ReadableByteChannel inChannel = Channels.newChannel(System.in);

ByteBuffer buffer = ByteBuffer.allocate(256);

while (true) {

buffer.clear();

inChannel.read(buffer);

buffer.flip();

String input = StandardCharsets.UTF_8.decode(buffer).toString().trim();

if ("exit".equalsIgnoreCase(input)) break;

System.out.println("You: " + input);

}

} catch (IOException e) {

e.printStackTrace();

}

});

executor.submit(() -> {

while (true) {

try {

Thread.sleep(3000);

System.out.println("Chatbot: I'm here to chat!");

} catch (InterruptedException e) {

Thread.currentThread().interrupt();

break;

}

}

});

executor.shutdown();

}

/**

* 55) Real-time Data Streaming (NIO-based version)

* Reads numeric inputs, computes a moving average, and writes results to a file.

*/

public static void realTimeDataStreaming(String outputFile) throws IOException {

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE, StandardOpenOption.APPEND);

ReadableByteChannel inChannel = Channels.newChannel(System.in);

ByteBuffer buffer = ByteBuffer.allocate(256);

List<Double> numbers = new ArrayList<>();

System.out.println("Enter numbers (type 'exit' to stop):");

while (true) {

buffer.clear();

inChannel.read(buffer);

buffer.flip();

String input = StandardCharsets.UTF_8.decode(buffer).toString().trim();

if ("exit".equalsIgnoreCase(input)) break;

try {

double num = Double.parseDouble(input);

numbers.add(num);

if (numbers.size() > 5) numbers.remove(0); // Keep last 5 entries for moving average

double avg = numbers.stream().mapToDouble(Double::doubleValue).average().orElse(0);

String logEntry = "Number: " + num + ", Moving Average: " + avg + "\n";

ByteBuffer logBuffer = ByteBuffer.wrap(logEntry.getBytes(StandardCharsets.UTF_8));

outChannel.write(logBuffer);

System.out.println("Current Moving Average: " + avg);

} catch (NumberFormatException e) {

System.out.println("Invalid number, try again.");

}

}

}

}