Question

1. Run the program and enter domain names to validate. Note that even valid input is flagged as invalid.
2. Change the program to validate a domain name. A valid domain name for this program has a second-level domain followed by a core gTLD. Run the program again.

   import java.util.Scanner;

   public class CoreGtldValidation {   
   public static void main (String [ ] args) {
   Scanner scnr = new Scanner(System.in);
   String coreGtld1;
   String coreGtld2;
   String coreGtld3;
   String coreGtld4;
   String inputName;
   String searchName;
   String theTld;
   boolean isCoreGtld;
   // FIXME: Add variable periodCounter to count periods in a domain name
   int periodPosition; // Position of the period in the domain name
   int i;

   coreGtld1 = ".com";
   coreGtld2 = ".net";
   coreGtld3 = ".org";
   coreGtld4 = ".info";
   theTld = "";
   isCoreGtld = false;
   periodPosition = 0;

   System.out.println("\nEnter the next domain name (<Enter> to exit): ");
   inputName = scnr.nextLine();

   while (inputName.length() > 0) {
   searchName = inputName.toLowerCase();
   isCoreGtld = false;
   
   // FIXME: Write a for loop using variable i to store in periodCounter
   // the number of periods in searchName. Store the position of the
   // period in periodPosition. If searchName has exactly one period
   // and searchName's first character is not a period, determine
   // whether searchName has a valid core gTLD by extracting the
   // domain name into variable coreGtld and comparing the name with
   // valid core gTLDs.

   // Extract the top-level domain name starting at the period's position.
   // Ex: If searchName = "example.com", the next statement extracts ".com"
   theTld = searchName.substring(periodPosition);

   if (theTld.equals(coreGtld1)) {
   isCoreGtld = true;
   }
   else if (theTld.equals(coreGtld2)) {
   isCoreGtld = true;
   }
   else if (theTld.equals(coreGtld3)) {
   isCoreGtld = true;
   }
   else if (theTld.equals(coreGtld4)) {
   isCoreGtld = true;
   }
   else {
   isCoreGtld = false;
   }
   
   System.out.print("\"" + inputName + "\" ");
   if (isCoreGtld) {
   System.out.println(" is a second-level domain followed by a core gTLD of \"" +
   theTld + "\"");
   }
   else {
   System.out.println("is not a second-level domain followed by a core gTLD.");
   }

   System.out.println("\nEnter the next domain name (or <Enter> to exit): ");
   inputName = scnr.nextLine();
   }
   }
   }

Answer 1

COMPLETED JAVA CODE:(CoreGtldValidation.java)

import java.util.Scanner;

public class CoreGtldValidation {
public static void main (String [ ] args) {
Scanner scnr = new Scanner(System.in);
String coreGtld1;
String coreGtld2;
String coreGtld3;
String coreGtld4;
String inputName;
String searchName;
String theTld;
boolean isCoreGtld;

int periodCounter=0; // variable periodCounter to count periods in a domain name
int periodPosition; // Position of the period in the domain name
int i;

coreGtld1 = ".com";
coreGtld2 = ".net";
coreGtld3 = ".org";
coreGtld4 = ".info";
theTld = "";
isCoreGtld = false;
periodPosition = 0;

System.out.println("\nEnter the next domain name (<Enter> to exit): ");
inputName = scnr.nextLine();

while (inputName.length() > 0) {
searchName = inputName.toLowerCase();
isCoreGtld = false;

// FIXME: Write a for loop using variable i to store in periodCounter
// the number of periods in searchName. Store the position of the
// period in periodPosition.

for(i=0;i<searchName.length();i++)
{
   if(searchName.charAt(i)=='.')
   {
       periodCounter++;
       periodPosition=i;
   }
  
}
// If searchName has exactly one period
// and searchName's first character is not a period, determine
// whether searchName has a valid core gTLD by extracting the
// domain name into variable coreGtld and comparing the name with
// valid core gTLDs.
// Extract the top-level domain name starting at the period's position.
// Ex: If searchName = "example.com", the next statement extracts ".com"

if(searchName.charAt(0)!='.' && periodCounter ==1)
  
theTld = searchName.substring(periodPosition);

if (theTld.equals(coreGtld1)) {
isCoreGtld = true;
}
else if (theTld.equals(coreGtld2)) {
isCoreGtld = true;
}
else if (theTld.equals(coreGtld3)) {
isCoreGtld = true;
}
else if (theTld.equals(coreGtld4)) {
isCoreGtld = true;
}
else {
isCoreGtld = false;
}

System.out.print("\"" + inputName + "\" ");
if (isCoreGtld) {
System.out.println(" is a second-level domain followed by a core gTLD of \"" +
theTld + "\"");
}
else {
System.out.println("is not a second-level domain followed by a core gTLD.");
}

System.out.println("\nEnter the next domain name (or <Enter> to exit): ");
inputName = scnr.nextLine();
}
}
}

SCREENSHOT FOR OUTPUT: