Basics_of_java.java

package com.learn;

import java.util.Arrays;
import java.util.Scanner;

public class Main {

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

        // variables

        String name = "Manan";

        //  primitive type

        int number = 007;
        double pi = 3.14;
        long phone = 7359251716L;
        byte temp = 127;
        float pi2 = 3.142F;
        char c = 'a';
        boolean flag = true;

        // new keyword

        String str = new String("Hello guys");

        //Strings

        String str1 = "lost";
        String str2 = "boy";

        String con_str = str1 + str2;
        System.out.println(con_str.charAt(4));
        String str3 = str1.replace('a','b');
        String sub = str1.substring(0,4);
        System.out.println(sub);

        // Arrays
        int len = 100;
        int[] array = new int[len];
        boolean[] bool_array = new boolean[len];

        int length = array.length;

        //sort array
        Arrays.sort(array);

        int[][] matrix= new int[len][len];

        // casting
        double price = 100.50;
        double final_price = price - 10;  // Example of implicit casting
        int cost = 100;
        int final_cost = cost - (int)18.9;  // Explicit casting

        // Constants
        final float PI = 3.14F;

        //Operators

        int val1 = 100;
        int val2 = 50;
        int sum  = val1 + val2 - (int)PI;
        int mod = val1 % val2;

        boolean antiflag = !flag;
        sum++;
        --sum;

        // Math class
        Math.max(val1,val2);

        double ran = 100*Math.random();

        //input
        Scanner sc = new Scanner(System.in);
        // int num = sc.nextInt();
        // String name2 = sc.next();   // input until space

        // String line = sc.nextLine(); // Inute line

        // comparison operators
        boolean is_eq = val1 ==val2;

        // Condition statements
        if(val1 > val2){
            System.out.println("Val1 is large");
        }
        else {
            System.out.println("Val2 is large");
        }

        // logical operators
        if(name=="Manan" &&val1 > 18){
            System.out.println("okay ");
        }

        // switch
        int day = 1;

        switch(day){
            case 1 :
                System.out.println("Monday");
            case 2:
                System.out.println("Tuesday");
                break;
            default:
                System.out.println("Holiday");
        }

        // loops

        for(int i =0 ; i < array.length ;i++){
            System.out.println(i);
            if(i==37){
                continue;
            }
        }

        int fl = 30;
        while(fl>0){
            System.out.println(fl);
            fl--;
        }

        int k =1;
        do{
            System.out.println("Enter Even number");
            k = sc.nextInt();
        }while(!isEven(k));

        // exception handling

        try{
            System.out.println(array[1000]);
        }catch(Exception ex){
            System.out.println("Inside Exception "+ ex);
        }

    }

    // function
    public static boolean isEven(int number){
        if(number % 2==1)
            return false;
        return true;
    }
}