//#4 Declaring & iniitializing Array

public class MyClass {
public static void main(String args[]) {

int arr[]; //declaring array
arr = new int[20]; // allocating memory

arr[0]= 55; //iniitializing first element
arr[1]= 33; //initi.... 2nd Element
System.out.println(arr[0]);
}
}

// #5 Atithmetic Operations in Java

public class MyClass {
public static void main(String args[]) {

// declaring variables
int add, sub, div, mul, rem;

// Declaring two varables
int x=4;
int y=2;

// performing Operations
add = x+y; // Addition
sub = x-y; // Subtraction
div = x/y; // Division
mul = x+y; // Multiply
rem= x%y; // reminder

// Showing results
System.out.println("4 + 2 = "+ add);
System.out.println("4 - 2 = "+ sub);
System.out.println("4 * 2 = "+ mul);
System.out.println("4 / 2 = "+ div);
System.out.println("4 % 2 = "+ rem);
}
}

//#6 2 Number Adder(Calculator) from user input

// This for Scan anything entered by user (user inputs)
import java.util.Scanner;

class myClass {
public static void main(String[] args) {

int x,y,Sum;

Scanner s = new Scanner(System.in);
// it will take input from keyboard

System.out.println("Enter 1st Number: ");
x = s.nextInt(); // scanning

System.out.println("Enter 2nd Number: ");
y = s.nextInt(); // scanning

Sum = x+y;
System.out.println("Sum = "+ Sum);
}
}

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// Percentage Calculator in Java

import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);

// #For_Taking_Total_Sub_and_Max_Marks
System.out.print("Total subjects: ");
int tsub = sc.nextInt();
System.out.print("\nMax Marks: ");
float mmark = sc.nextInt();
System.out.println("");

int [] arr = new int[tsub];

// #For_taking_Subject_values
for (int i =0; i< tsub;i++){
System.out.print("Enter Marks of "+(i+1)+": ");
arr[i] = sc.nextInt();
}

float percent, avg=0, iper;

// #For_Showing_Results_and_Percentage
for (int i =0; i< tsub;i++){
System.out.println("\nMarks of "+(i+1)+" is "+arr[i]);
iper = ((arr[i]/mmark)*100);
System.out.println("Percentage of "+(i+1)+" is "+ iper);
avg = avg + iper;
}

percent = avg/tsub;

System.out.println("\nTotal Percent: "+ percent+ "%");

}
} // @Java_Codes_Pro

//enum code for advance java

enum Day{
SUN("sunday"), MON("monday"), TUE("tuesday"), WED("wednesday"), THU("thursday"), FRI("friday"), SAT("saturday");
public String Valu;
Day(String valu){
this.Valu = valu;
}

public String getValue(){
return Valu;
}
}

public class Main {
public static void main(String[] args) {
Day d = Day.MON;
System.out.println("Enum name: " + d.name() + " Value is " + d.getValue());

for(Day e: Day.values()){
System.out.println(e.name() + " " +e.getValue());
}
}
} // @Java_Codes_pro

// Serialization - Deserialization Advance java concept

// Warning : for using this code change path of 'filename' (written below in Serializ class) to your file path

import java.io.*;

class Student implements Serializable {
private static final long serialVersionUID = 1L;

private String name;
private int age;
private String address;
// transient int x; if we create this then this will be no serialized

public Student(String name, int age, String address) {
this.name = name;
this.age = age;
this.address = address;
}

public void setName(String name) {
this.name = name;
}

public void setAge(int age) {
this.age = age;
}

public void setAddress(String address) {
this.address = address;
}

public String getName() {
return name;
}

public int getAge() {
return age;
}

public String getAddress() {
return address;
}

public String get(String z){
return z;
}

public int get(int age){
return age;
}

@Override
public String toString() {
return ("Student name is " + this.getName() + ", age is " + this.getAge() + ", and address is "
+ this.getAddress());
}
}

public class Serializ {
public static void main(String[] args) {
Student student = new Student("Sid", 19, "UP India");
FileOutputStream fileOut = null;
ObjectOutputStream objOut = null;
String filename = "C:\\Users\\mynms\\Desktop\\BCA\\Code\\Java2\\unit 4\\Test.txt";
// Serialization
try {
fileOut = new FileOutputStream(filename);
objOut = new ObjectOutputStream(fileOut);

objOut.writeObject(student);
objOut.close();
fileOut.close();

System.out.println("Object has been serialized: " + student);
} catch (Exception e) {
System.out.println("Not Serialized");
}

// Deserialization
FileInputStream fileIn = null;
ObjectInputStream objIn = null;

try {
fileIn = new FileInputStream(filename);
objIn = new ObjectInputStream(fileIn);

Student object = (Student) objIn.readObject();

System.out.println("Object has been deserialized " + object);

objIn.close();
fileIn.close();

} catch (IOException e) {
System.out.println("IO Exception " + e);
}
catch(ClassNotFoundException e){
System.out.println("Class not found exception " + e);
}
}
} // @Java_Codes_Pro

// File input Output Byte stream : Advance Java
// Warning : to use this code please change following path

import java.io.*;

public class File {
public static void main(String[] args) throws IOException {
FileInputStream inStream = new FileInputStream(
"C:\\Users\\mynms\\Desktop\\BCA\\Code\\Java2\\unit 4\\ReadFrom.txt");

FileOutputStream outStream = new FileOutputStream(
"C:\\Users\\mynms\\Desktop\\BCA\\Code\\Java2\\unit 4\\SendTo.txt");

// Reads byte at a time, it reached end of the file, returns -1
int content;

try {
while ((content = inStream.read()) != -1) {
outStream.write((byte) content);
}
System.out.println("File transfer conpleted successfully");
}

finally{
if (inStream != null)
inStream.close();

if (outStream != null)
outStream.close();
}
}
} // @Java_Codes_Pro

// File input Output Byte stream : Advance Java

// Counting spaces, fullstops, characters, words and transfering

// Warning : to use this code please change following path

import java.io.*;

public class filecount {

static boolean isChar(int content){
return (content > 64 && content < 91 || content > 96 && content < 124);
}
public static void main(String[] args) throws IOException {

FileInputStream inStream = new FileInputStream(
"C:\\Users\\mynms\\Desktop\\BCA\\Code\\Java2\\unit 4\\ReadFrom.txt");

FileOutputStream outStream = new FileOutputStream(
"C:\\Users\\mynms\\Desktop\\BCA\\Code\\Java2\\unit 4\\SendTo.txt");

// Reads byte at a time, it reached end of the file, returns -1
int content;
int whitespaces = 0;
int fullstops = 0, chars = 0, words = 0;
boolean w = false;

try {
while ((content = inStream.read()) != -1) {
outStream.write((byte) content);

if(' ' == content)
whitespaces = whitespaces + 1;

if('.' == content)
fullstops += 1;

if(isChar(content)){
w = true;
chars += 1;
}
else if(w){
words += 1;
w = false;
}

}
if(isChar(content)){
w = true;
chars += 1;
}
else if(w){
words += 1;
w = false;
}

System.out.println("Whitespaces: " + whitespaces + "\nCharacters: " + chars + "\nFullstops: " + fullstops + "\nWords: "+ words);

System.out.println("File transfer conpleted successfully");

} finally{
if (inStream != null)
inStream.close();

if (outStream != null)
outStream.close();
}
}

} // @Java_Codes_Pro

// Server Code

import java.net.*;
import java.io.*;

class Server {
ServerSocket server;
Socket socket;
BufferedReader br;
PrintWriter out;

// Constructor

public Server() {
try {
server = new ServerSocket(7777);
System.out.println("Server is ready to accept connection");
System.out.println("Waiting for client");
socket = server.accept();

br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream());

startReading();
startWritting();

}
catch (Exception e) {
e.printStackTrace();
}

}

public void startReading() {
// thread reading
Runnable r1 = () -> {
System.out.println("Reader started..");

try {
while (true) {
String msg = br.readLine();
if (msg.equals("exit")) {
System.out.println("Client terminated the chat, Please press enter to free port");
socket.close();
break;
}
System.out.println("Client: " + msg);
}
} catch (Exception e) {
System.out.println("Connection Closed");
}
};
new Thread(r1).start();
}

public void startWritting() {
// thread sending data
Runnable r2 = () -> {
System.out.println("Writter started..");
String content = "";
try {
while (!socket.isClosed()) {

BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
content = br1.readLine();
out.println(content);
out.flush();

if (content.equals("exit")) {
System.out.println("You terminated the chat");
socket.close();
break;
}
}
}
catch (Exception e) {
if (content.equals("exit")) {
System.out.println("Connection Closed successfully");
}
else{
System.out.println("Connection terminated unsuccssefully \nTermnate all existing cmd's or check other errors");
}
}
};
new Thread(r2).start();
}

public static void main(String[] args) {
System.out.println("This is server.. going to start server");
new Server();
}
} // Server C

import java.io.*;
import java.net.*;

public class Client {
Socket socket;
BufferedReader br;
PrintWriter out;

public Client() {

try {
System.out.println("Connecting to the server.");
socket = new Socket("127.0.0.1", 7777);
System.out.println("Connection successfull..");

br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream());

startReading();
startWritting();

} catch (Exception e) {
System.out.println("Error: Firstly run Server Code");
}
}

public void startReading() {
// thread reading
Runnable r1 = () -> {
System.out.println("Reader started..");
try {
while (true) {

String msg = br.readLine();
if (msg.equals("exit")) {
System.out.println("Server terminated the chat, Please press enter to free port");
socket.close();
break;
}
System.out.println("Server: " + msg);
}
} catch (Exception e) {
System.out.println("Connection Closed");
}
};
new Thread(r1).start();
}

public void startWritting() {
// thread sending data
Runnable r2 = () -> {
System.out.println("Writter started..");
String content = "";
try {
while (!socket.isClosed()) {

BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));

content = br1.readLine();

out.println(content);
out.flush();

if (content.equals("exit")) {
System.out.println("You terminated the chat");
socket.close();
break;
}
}
} catch (Exception e) {
if (content.equals("exit")) {
System.out.println("Connection Closed successfully");
}
else{
System.out.println("Connection terminated unsuccssefully \nTermnate all existing cmd's or check other errors");
}
}
};
new Thread(r2).start();
}

public static void main(String[] args) {
System.out.println("Going to start Client..");
new Client();
}
} // Client Code : @Java_Codes_Pro

Java Chat Code(2 Program sent Copy both (Server Code and Client Code) run And Practice with them)

// Factotial from recursion in java

import java.util.Scanner;

public class Main {
public static void main(String[] args) {

Scanner s = new Scanner(System.in);
System.out.print("Enter Number: " );
int n = s.nextInt();
if(n>26)
System.out.print("Please enter number less than 25\n" );
else{

System.out.println("Showing factorial for "+ n + " Number" );
System.out.print("\n" +Main.f(n));
}
}

// Factorial value calculation + series printing
static long f(long n){
if (n==1){
System.out.print(n);
return n;
}
else{
System.out.print(n + " * ");
return n*f(n-1);
}
}

} // @Java_Codes_Pro

// Factotial from loop in java
// see recursive approach in upper code
import java.util.Scanner;

public class Main {
public static void main(String[] args) {

Scanner s = new Scanner(System.in);
System.out.print("Enter Number: " );
int n = s.nextInt();
if(n>26)
System.out.print("Please enter number less than 25\n" );
else{

System.out.println("Showing factorial for "+ n + " Number" );
System.out.print("\n" +Main.f(n));
}
}

// Factorial value calculation + series printing
static long f(int n){
long h = 1;
for(int i = n; 0 < i; i-- ){
if(i == 1){
System.out.print(i);
continue;
}
System.out.print(i +" * " );
h = i*h;
}
return h;
}
}
// Join now @Java_Codes_Pro

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// java basic threads example

public class MultithreadingExample {
    public static void main(String[] args) {

        // Creating and starting two threads
        Thread thread1 = new MyThread("Thread 1");
        Thread thread2 = new MyThread("Thread 2");
        thread1.start();
        thread2.start();
    }
}

class MyThread extends Thread {
    private String threadName;

    public MyThread(String name) {
        threadName = name;
    }

    public void run() {
        for (int i = 1; i <= 5; i++) {
            System.out.println(threadName + " - Count: " + i);
            try {
                Thread.sleep(1000); // Pause for 1 second
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
} // @Java_Codes_Pro

// #1 Your First Program

class HelloWorld {

public static void main(String[] args){
    System.out.println("Hello, World!");
     }

}

// #2 For Adding 2 numbers

public class MyClass {

public static void main(String args[]) {
int x=10;
int y=25;
int z=x+y;
System.out.println("Sum of x+y = " + z);
}

}

// Airthmetic Operations in Java

public class MyClass {
  public static void main(String args[]) {
    
   // declaring variables
     int add, sub, div, mul, r;
    
     // Declaring two varables
     int x=4;
     int y=2;
    
    // performing Operations
     add = x+y;    // Addition
     sub = x-y;     // Subtraction
     div = x/y;      // Division
     mul = x+y;     // Multiply
     r= x%y;     // re m inder
    
   // Showing results
     System.out.println("4 + 2 = "+ add);
     System.out.println("4 - 2 = "+ sub);
     System.out.println("4 * 2 = "+ mul);
     System.out.println("4 / 2 = "+ div);
     System.out.println("4 % 2 = "+ r);
  }
}

// in this i introduced operators in java
// code by @Java_Codes_Pro
// buttons by @IOChannel_Bot
// Compiler @Compiler0bot