Page 338 62-64-66-68

62.
package com.company;
import java.util.*;
import java.lang.*;

public class EmailChecker {
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Type in your email");
        String email = input.next();
        int length = email.length();
        int counter = 0;
        int atCounter = 0;
        char currentLetter = email.charAt(counter);
        while(counter < length-1){
            if( currentLetter == '@'){
                atCounter++;
            }
            counter++;
            currentLetter = email.charAt(counter);
        }
        if(atCounter == 1){
            System.out.println("The email is valid");
        }
        else{
            System.out.println("The email is invalid");
        }
    }
}





64.
package com.company;
import java.util.*;
import java.lang.*;

public class DecimalToBinary {
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Type in a number");
        int num = input.nextInt();
        System.out.println("The binary form is: "+Integer.toBinaryString(num));
    }
}




66.
package com.company;
import java.util.*;
import java.lang.*;

public class XOReplicator {
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Type in a binary number");
        String email = input.next();
        int length = email.length();
        int counter = 1;
        int falseCounter = 0;
        int trueCounter = 0;
        char currentLetter = email.charAt(counter);
        char previousLetter = email.charAt(counter-1);
        while(counter < length-1){
            if( currentLetter == previousLetter){
                falseCounter++;
            }
            else{
                trueCounter++;
            }
            counter+=2;
            currentLetter = email.charAt(counter);
            previousLetter = email.charAt(counter-1);
        }
        if(falseCounter == trueCounter){
            System.out.println("False");
        }
        else{
            System.out.println("True");
        }
    }
}





68.
package com.company;
import java.util.*;
import java.lang.*;

public class HTMLvalidator {
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Type in your code");
        String code = input.next();
        int length = code.length();
        int counter = 0;
        int symbolCounter1 = 0;
        int symbolCounter2 = 0;
        char currentLetter = code.charAt(counter);
        while(counter < length-1){
            if( currentLetter == '<'){
                symbolCounter1++;
            }
            if( currentLetter == '>'){
                symbolCounter2++;
            }
            counter++;
            currentLetter = code.charAt(counter);
        }
        if(symbolCounter1 == symbolCounter2){
            System.out.println("The code is valid");
        }
        else{
            System.out.println("The code is invalid");
        }
    }
}