java program to check internet connected or Not

// Java program for Testing Internet connectivity
import java.util.*;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;

class TestInternetConnectioin {
    public static void main(String args[])
    {
        try{
//URL class for set site url
URL url = new URL("https://www.google.co.in");
URLConnection connection = url.openConnection();
connection.connect();

//if successfully open than
System.out.println("Internet Connected Successfully....");
}catch(Exception E){
// if conncetion not open than exception arise it means not connected
System.out.println("Internet Not Connected...");
}
    }
}

how to make a file read only using java Program Demo

how to update elements in ArrayList in java.

convert primitive double to Double object : JAVA PROGRAM

video Link :https://youtu.be/McEufMJ_SY4

Source :

/* java program to convert primitive double to Double Object */

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

// primitive double value
double dvalue = 5444.22 ;

// convert double to Double by creating Double Object

Double dobj = new Double(dvalue);

System.out.println("value of Double Object is: "+dobj);
}
}

JAVA program to check given string is number or not

Video Link : ➽ https://youtu.be/KLVLYuDT2-o

Source program :

import java.util.Scanner;
class NumberValidation{
public static void main(String args[]){
String str ;
System.out.println("Enter String :");

Scanner sc = new Scanner(System.in);
str = sc.next();

boolean b = true;

try{
Double.parseDouble(str);
}catch(NumberFormatException ex){
b = false;
}

if(b){
System.out.println("\n\n Enter String is number ...");
}else{
System.out.println("\n\n Enter String is Not a number ...");
}
}
}

Convert Upper to Lower And Lower to Upper Case Letter in java by String Method-Practical Demo

https://youtu.be/wnetHZ-bSuw

substring() method in java/android : String Method Example

https://youtu.be/FYtMmpXlLqw